U.S. patent application number 14/820624 was filed with the patent office on 2016-03-24 for platform system for greenhouse roof.
The applicant listed for this patent is E I DU PONT DE NEMOURS AND COMPANY. Invention is credited to PAUL J. ARNOLD, DAVID C. HEWLETT, LOUIS G. ROSANIO, DAVID A. SHILDT, DAVID CARLTON VISSER, MARK JEFFERSON WHITLEY, ROBERT P. WOODMAN.
Application Number | 20160083969 14/820624 |
Document ID | / |
Family ID | 55525256 |
Filed Date | 2016-03-24 |
United States Patent
Application |
20160083969 |
Kind Code |
A1 |
ARNOLD; PAUL J. ; et
al. |
March 24, 2016 |
PLATFORM SYSTEM FOR GREENHOUSE ROOF
Abstract
A platform system useful for constructing, maintaining, or
repairing greenhouse roofs comprises a platform section providing a
working area surface formed with removable treads supported on left
and right platform rails. The platform section is supported by
downwardly projecting upper and lower support bases appointed to
rest on structural members of the roof, thereby providing a
clearance between the working area surface and the roof beneath.
Guardrails extend along the sides of the platform section between
guardrail posts attached at the upper and lower ends of the
platform rails. The system is light-weight, minimizing the loading
imposed on the roof and permitting it to be readily positioned by a
small work crew. The support base may include retractable rollers
that permit it to be slid upward across the eaves and onto the
roof. A deployment assist cart may be used to erect, support, and
access the platform system.
Inventors: |
ARNOLD; PAUL J.; (ELKTON,
MD) ; HEWLETT; DAVID C.; (WILMINGTON, DE) ;
ROSANIO; LOUIS G.; (WILMINGTON, DE) ; SHILDT; DAVID
A.; (MIDDLETOWN, DE) ; VISSER; DAVID CARLTON;
(WILMINGTON, DE) ; WHITLEY; MARK JEFFERSON;
(LAUREL SPRINGS, NJ) ; WOODMAN; ROBERT P.; (WEST
CHESTER, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
E I DU PONT DE NEMOURS AND COMPANY |
Wilmington |
DE |
US |
|
|
Family ID: |
55525256 |
Appl. No.: |
14/820624 |
Filed: |
August 7, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62053277 |
Sep 22, 2014 |
|
|
|
Current U.S.
Class: |
182/45 ;
182/113 |
Current CPC
Class: |
E04G 3/22 20130101; E04D
15/04 20130101; E06C 7/12 20130101; E04G 2001/242 20130101; Y02A
40/25 20180101; E06C 7/16 20130101; E06C 1/397 20130101; A01G 9/14
20130101; E04G 1/15 20130101; E04G 2003/286 20130101; Y02A 40/252
20180101 |
International
Class: |
E04G 3/22 20060101
E04G003/22; E04G 3/28 20060101 E04G003/28; E04G 5/14 20060101
E04G005/14 |
Claims
1. A platform system elongated along a platform length direction
between a lower end and an upper end and having opposing left and
right sides separated along a platform width direction, the
platform system being configured for placement on a roof structure
and comprising: (a) left and right upper-end guardrail posts and
left and right lower-end guardrail posts; (b) a platform section
that extends along the platform length direction for a platform
length and comprises: (i) left and right platform rails that are
disposed in spaced-apart, parallel relationship and extend
horizontally along the length of the platform section between the
upper and lower ends of the platform system, the upper-end
guardrail posts and the lower-end guardrail posts being attached to
the respective platform rails, (ii) a plurality of platform treads
disposed along at least a portion of the platform length, each
tread having left and right edges and spanning the left and right
platform rails and being removably secured thereto, the treads
collectively defining a working platform area having a platform
width sufficient to accommodate a worker and a preselected working
length defined by the number of treads present, and (iii) left and
right guardrails that extend horizontally along the respective
sides of the platform system for substantially the platform length,
are attached to the respective left and right platform rails
through the lower and upper guardrail posts, and are situated at a
preselected height above the platform area; (c) an upper support
base proximate the upper end and comprising an upper horizontal
member; and (d) a lower support base proximate the lower end and
comprising a lower horizontal member, and wherein the upper and
lower support bases project downward from the platform section and
are configured to rest on the roof structure to support the
platform system and maintain a clearance between the roof structure
and the platform section.
2. The platform system of claim 1, further comprising a roller
assembly associated with the upper support base, the roller
assembly comprising one or more rollers having a retracted position
and an extended position, the roller assembly being configured such
that when the platform system is placed on a roof structure: (a)
with the rollers in the retracted position the upper support base
is in contact with the roof structure; and (b) with the rollers in
the extended position the rollers are in contact with the roof
structure and the upper support base is elevated above the roof
structure, thereby permitting the platform system to be rolled
along the platform length direction.
3. The platform system of claim 2, wherein the roller assembly
comprises a spring mechanism that is operable to urge the one or
more rollers downward into the extended position and has a
compliance such that imposition of at least a predetermined weight
on the platform system is sufficient to overcome the downward
urging and drive the one or more rollers into the retracted
position.
4. The platform system of claim 2, wherein the roller assembly
comprises at least two rollers, one of the at least two rollers
being situated on each of the left and right sides of the platform
system.
5. The platform system of claim 1, further comprising a roller
assembly associated with each of the upper and lower support bases,
each roller assembly comprising one or more rollers having a
retracted position and an extended position, the roller assemblies
being configured such that when the platform system is placed on a
roof structure: (a) with the one or more rollers in the retracted
position the support bases are in contact with the roof structure;
and (b) with the one or more rollers in the extended position the
rollers are in contact with the roof structure and the support
bases are elevated above the roof structure, thereby permitting the
platform system to be rolled along the platform length
direction.
6. The platform system of claim 5, wherein each roller assembly
comprises a spring mechanism that is operable to urge the one or
more rollers of the roller assembly downward into the extended
position and has a compliance such that imposition of at least a
predetermined weight on the platform system is sufficient to
overcome the downward urging and drive the one or more rollers of
each roller assembly into the retracted position.
7. The platform system of claim 1, further comprising a plurality
of tread attachments, at least one of which is disposed proximate
each edge of each of the platform treads to removably secure the
platform treads to the platform rails.
8. The platform system of claim 7, wherein each tread attachment
comprises a stud having an enlarged head and upstanding from one of
the respective platform rails, and at least one keyhole-shaped slot
is provided proximate each edge of each platform tread, each
keyhole-shaped slot being configured for locking engagement with
one of the studs.
9. The platform system of claim 1, further comprising a plurality
of anchorages, each configured to engage a locking clip of a
personal fall arrest system.
10. The platform system of claim 9, wherein the anchorages comprise
one or more discrete anchorage points spaced along each of the
guardrails and attached thereto, each anchorage point providing an
aperture configured to engage the locking clip.
11. The platform system of claim 1, wherein the upper-end guardrail
posts and the upper support base are formed as an upper end
assembly and the lower-end guardrail posts and the lower support
base are formed as a lower end assembly, and the upper and lower
end assemblies are separably joined to the platform section by
connections made at points of engagement between the guardrails and
the platform rails and the end assemblies.
12. The platform system of claim 1, being capable of supporting a
rated load of at least 200 kg and having a ratio of an unloaded
weight "W" of the platform system to a full working area "A" that
is at most 8 pounds per square foot of working area.
13. The platform system of claim 1, wherein the left and right
platform rails and the left and right guardrails are each comprised
of a plurality of subsections that are collinearly disposed and
separably joined together in a locking connection to form the
respective platform rails and guardrails.
14. The platform system of claim 13, further comprising: a coupling
support assembly situated intermediate the upper and lower ends and
comprising a middle support base comprising a middle horizontal
member and left and right middle guardrail posts connected to the
middle support base, and wherein respective subsections of the
platform rails and the guardrails are separably joined together
through locking connections made using connectors disposed at
points of engagement on the coupling support assembly.
15. The platform system of claim 14, wherein each of the connectors
comprises a first connector element attached to an end of the
respective platform rail or guardrail subsection, a second
connector element attached to the coupling support assembly, and a
locking pin, the connector elements being configured to be joined
in mating relationship and secured to each other by mutual
engagement with the locking pin, the first connector element being
one of a connector pin and a mating socket and the second connector
element being the other of the connector pin and the mating
socket.
16. A platform erection system, comprising the platform system of
claim 1 and a deployment assist cart comprising: (a) a platform
base section; (b) a deployment support upstanding from the platform
base section; (c) deployment rails connected to the deployment
support and configured to receive the platform system for
deployment on a roof structure.
17. The platform erection system of claim 16, wherein the
deployment rails are rotatable between a loading position
configured to accept the platform system and a deployment position
configured to permit the platform system to be maneuvered from the
deployment rails onto a surface of the roof structure.
18. A method of providing access to a structure, comprising: (a)
providing a platform system as recited by claim 1; and (b)
disposing the platform system on a flat or sloped area of the
structure, whereby access is provided to the area.
19. A kit, comprising parts that, when assembled, are capable of
forming the platform system of claim 1.
20. The kit of claim 19, further comprising parts that, when
assembled, are capable of forming a deployment assist cart
comprising: (a) a platform base section; (b) a deployment support
upstanding from the platform base section; (c) deployment rails
connected to the deployment support and configured to receive the
platform system for deployment on a roof structure.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims benefit of U.S. Provisional Patent
Application Ser. No. 62/053,277, filed Sep. 22, 2014, and entitled
"Platform System For Greenhouse Roof," which is incorporated herein
in its entirety for all purposes by reference thereto.
FIELD OF THE INVENTION
[0002] The present invention relates to a platform useful for
safely constructing, maintaining, and repairing the roofs of
greenhouses and other like building structures, which are
relatively fragile and cannot sustain excessive loads.
TECHNICAL BACKGROUND
[0003] Greenhouses have long been used to provide a controlled
climate for growing plants. Typically a greenhouse includes a
skeletal structure made of metal (or possibly wood) supporting a
roof formed of a material that is transparent to light but
impervious to the passage of air or precipitation. Glass and
plastic or polymeric materials are commonly used. Often the same
materials are used to construct some or all of the walls of the
greenhouse.
[0004] Light from the sun incident on a greenhouse includes
radiation in both visible and infrared (heat) wavelengths. Some of
this light passes through the walls and roof and is absorbed,
heating the interior of the greenhouse and its contents. The walls
and roof provide a closed construction that minimizes loss of that
heat through unwanted circulation of the interior air to the
exterior. Plants grown in a greenhouse can thus be kept warmer than
they would be if simply situated in ambient air. Sometimes natural
light is supplemented by artificial light. The inside air can also
be heated and/or cooled and may be circulated by fans.
[0005] Greenhouses are used worldwide for a number of purposes,
including their use to extend the typical growing season at both
ends for plants and to permit plants to be cultivated in a given
climate zone in which they otherwise could not be sustained. For
example, in temperate climates, plants can be started from seed
much earlier in the spring and may continue to produce flowers or
fruit much later into the fall than they otherwise would. Many
greenhouses are used to raise plants on a commercial scale that are
either ornamental or produce edible fruits or vegetables.
Greenhouses are also used to raise exotic or tropical plants for
display in botanical gardens or to provide such plants to florists,
and for horticultural and other botanical research projects.
[0006] Greenhouses are found in many configurations. For some, such
as those in botanical parks and other public spaces, aesthetic
appeal is a paramount design factor, so architects have included
intricate, multi-planar or curvilinear roof shapes. On the other
hand, utilitarian factors such as efficiency and minimizing costs
of construction, operation, and maintenance govern the vast
majority of designs for commercial greenhouses. The smallest sizes
are sometimes built with a simple metal frame structure covered
with a flexible film of material such as polyethylene. However,
this construction has limited durability and resistance to wind and
precipitation (rain, snow, hail, etc.), so roofs of larger
commercial structures are commonly built with simple shapes having
a limited number of large, planar surfaces formed with rigid panels
of glass or comparable plastic materials.
[0007] For example, a common greenhouse structure is depicted
generally at 10 in FIG. 1. Greenhouse 10 has side supporting walls
20 and end or gable walls 21. The roof configuration shown is
frequently termed a pitched or sloped roof; it includes two large,
planar, sloped sides 12 that join at an apex 14 to form a
configuration having the shape of an inverted vee, when viewed from
an end wall. A skeletal structure includes a series of rafters 16
that extend on both sides between a ridge beam 18 and eaves 19,
which are formed at the junction of roof side 12 and the
corresponding side supporting wall 20. Wall supports 17 are
included in both side and end walls 20, 21. One or more cross
members 22 run transverse to, and are supported by, rafters 16.
Often, some or all of rafters 16 form part of a truss structure
(not shown) as required to support a preselected design load.
Ordinarily, the design load accounts for: the static structure of
the building and its appointments; wind and snow loading; and
incidental loading (often termed "live loading"), such as that
resulting from workers servicing the roof.
[0008] The horizontal spacing between adjacent rafters 16 is
ordinarily governed by the size of glass panels 26 that can be
effectively supported just at their lateral edges 30 at the
selected roof pitch. In a common configuration, the glass panels
are installed in a shingled fashion, beginning from the eaves
upward toward the ridge, with each successive ascending panel being
lapped slightly over its lower predecessor to minimize the
intrusion of precipitation and wind. The glass panels may be
secured using a technique apparent in the detailed, cross-sectional
view of FIG. 2. The lateral edges 30 of panels 26 are received in
channels of an elastomeric, compliant gasket structure or caulking
36. The gasketing in turn is sandwiched between a rafter (here
shown as a box beam 34) and a glazing bar 32 mounted above, and
running parallel to, beam 34. Together, the box beam 34 and the
attached glazing bar 32 are frequently termed a purlin. A fastener,
such as screw 40 with a corresponding elastomeric sealing washer
42, secures the glazing bar 32 and the glass panels 26. The glazing
bars 32 can be readily removed to allow replacement of glass panels
26.
[0009] Frequently a ridge vent (not shown) is created at or near
the ridge beam 18; it may be selectively openable to permit
adjustment of the ventilation in the building. In some designs,
some or all of the glass panels adjacent the ridge are mounted in
openable frames to provide the ventilation. Additional glass panels
elsewhere in the roof may also be made openable for additional
ventilation. The structural members are almost always metal,
although wood or other materials could be used.
[0010] Larger greenhouses are sometimes constructed by joining
additional pairs of roof sections that alternate in slope, a form
sometimes termed "ridge and furrow." For example, a configuration
having the shape of an inverted letter "W" (as seen in end view)
could be formed using four planar sections. Such construction
provides a structure having increased width, while maintaining the
slope angle of the individual sections, but without increasing the
overall height, as would be required for a single vee-shaped
structure of the same roof slope and width.
[0011] It will be understood that the term "glass" is used herein
to refer either to conventional glass panels of the types used
ubiquitously in construction or to other frangible, transparent or
translucent panel materials such as poly(methyl methacrylate)
(e.g., PLEXIGLAS.RTM.) and polycarbonate (e.g., LEXAN.RTM.) that
are also commonly used. Greenhouses are commonly constructed with
ordinary soda-lime window glass, but more advanced tempered and
laminated safety glasses are sometimes used. These advanced glass
and plastic materials typically cost more but afford some
advantages of improved safety and durability.
[0012] Society has increasingly recognized the importance of
providing safety systems and equipment to mitigate or prevent
injury to workers during building construction, operation, and
maintenance. The prevalence of injuries in the past has prompted
industry to voluntarily improve its own standards and practices.
Regulations have also been imposed by governmental agencies. In
general, safety practices that address these requirements are known
and relatively easy to implement in many conventional construction
and later maintenance and repair operations. However, the extensive
use of frangible materials like glass in greenhouse roofs presents
significant challenges that go beyond what is encountered with
other, more common building types. For example, the hazard of
falling off a roof is common to all buildings, but a worker on a
greenhouse is additionally vulnerable to falling through a glass
roof panel and being lacerated by broken glass or injured by
hitting internal structural members or a hard ground surface
attendant to the fall below. An even greater potential for serious,
even life-threatening, injury is apparent.
[0013] Inevitably, glass roofs are vulnerable to damage during
construction and during their ordinary use, whether resulting from
inadvertent human actions or from external causes, like hail or
other falling objects. Post-construction repairs often must be done
quickly and under adverse conditions, which typically heighten the
likelihood of accidents.
[0014] Repairs are sometimes made from a suitably positioned cherry
picker crane that provides a worker access from a platform
suspended above a work area. However, implementing this approach is
typically costly, and a suitable ground location for the cherry
picker close enough to the roof area may not be available.
[0015] Thus, workers often resort to planks or ladders placed
directly onto the roof structure to form a makeshift working
surface from which a worker can perform required repairs. However,
these approaches do not afford acceptable safety, as safety
equipment and precautions effectively used for conventional
buildings are inadequate, inapplicable, or inoperable.
[0016] For example, fall protection is ordinarily required for
persons such as roofers working more than a few feet off the
ground. In some instances, railing systems associated with scaffold
platforms or ladders are adequate, but often, workers must have
mobility that makes these systems difficult or impossible to
implement, so other approaches are needed.
[0017] Although various safety equipment and methods are known,
including those described above, there nevertheless remains a need
for systems that facilitate construction and repair of roofs of
greenhouses and other buildings.
SUMMARY OF THE INVENTION
[0018] An aspect of the invention relates to a platform system
elongated along a platform length direction between a lower end and
an upper end and having opposing left and right sides separated
along a platform width direction, the platform system being
configured for placement on a roof structure and comprising:
[0019] (a) left and right upper-end guardrail posts and left and
right lower-end guardrail posts;
[0020] (b) a platform section that extends along the platform
length direction for a platform length and comprises: [0021] (i)
left and right platform rails that are disposed in spaced-apart,
parallel relationship and extend horizontally along the length of
the platform section between the upper and lower ends of the
platform system, the upper-end guardrail posts and the lower-end
guardrail posts being attached to the respective platform rails,
[0022] (ii) a plurality of platform treads disposed along at least
a portion of the platform length, each tread having left and right
edges and spanning the left and right platform rails and being
removably secured thereto, the treads collectively defining a
working platform area having a platform width sufficient to
accommodate a worker and a preselected working length defined by
the number of treads present, and [0023] (iii) left and right
guardrails that extend horizontally along the respective sides of
the platform system for substantially the platform length, are
attached to the respective left and right platform rails through
the lower and upper guardrail posts, and are situated at a
preselected height above the platform area;
[0024] (c) an upper support base proximate the upper end and
comprising an upper horizontal member; and
[0025] (d) a lower support base proximate the lower end and
comprising a lower horizontal member, and wherein the upper and
lower support bases project downward from the platform section and
are configured to rest on the roof structure to support the
platform system and maintain a clearance between the roof structure
and the platform section.
[0026] In some implementations, the present platform system is
modularized, comprising a plurality of constituent parts or
subassemblies that may be assembled and disassembled repeatedly.
Modular construction facilitates convenient transportation and
storage of the system, and permits the platform system to be
adapted so it can be used to access roofs of different sizes and
configurations.
[0027] Another aspect provides a platform erection system wherein
the present platform system is used in conjunction with a
deployment assist cart that comprises:
[0028] (a) a platform base section;
[0029] (b) a deployment support upstanding from the platform base
section;
[0030] (c) deployment rails connected to the deployment support and
configured to receive the platform system for deployment on the
roof structure.
[0031] In an implementation, the deployment rails are rotatable
between a loading position configured to accept the platform system
and a deployment position configured to permit the platform system
to be maneuvered from the deployment rails onto a surface of the
roof structure. The deployment assist cart is beneficially employed
in any of the transportation, erection, and support and
stabilization of the platform system on a roof structure.
[0032] A further aspect provides a kit that comprises parts that,
when assembled, are capable of forming the platform system of the
present disclosure. In another implementation, the kit further
comprises parts that, when assembled, are capable of forming the
present deployment assist cart, which is configured to receive the
platform system for deployment on a roof structure.
[0033] A still further aspect provides a method that provides
access to a structure that may, without limitation, be a greenhouse
roof structure. The method comprises providing the platform system
of the present disclosure and disposing the platform system on a
flat or sloped area of the structure, whereby access is provided to
the area.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The present disclosure will be more fully understood and
further advantages will become apparent when reference is made to
the following detailed description of certain of the preferred
embodiments and the accompanying drawings, wherein like reference
numerals denote similar elements throughout the several views and
in which:
[0035] FIG. 1 depicts in perspective view a schematic form of a
conventional greenhouse having a pitched roof;
[0036] FIG. 2 depicts in a detailed, cross-sectional view (taken at
2-2 in FIG. 1) a conventional attachment of glass roof panels to a
supporting rafter using a glazing bar;
[0037] FIG. 3 depicts in perspective view a schematic form an
implementation of the present platform system;
[0038] FIG. 4 depicts in side elevation view a tread attachment
used in an embodiment of the present platform system;
[0039] FIGS. 5A-5B depict details of one possible tread attachment
employed to secure platform treads to the platform rails of an
embodiment of the present platform system; FIG. 5A is a top plan
view of a portion on the left side of the platform system and FIG.
5B is a cross-sectional view taken at 5B-5B in FIG. 5A;
[0040] FIGS. 6A-6B depict in perspective view a roller assembly
that includes a spring mechanism employed in an embodiment of the
present platform system, with the roller depicted in its retracted
and extended positions in FIGS. 6A and 6B, respectively;
[0041] FIG. 7 depicts an inclined platform tread included in an
embodiment of the present platform system, taken in side elevation
view;
[0042] FIG. 8 depicts in perspective view a modular platform
systemof the present disclosure;
[0043] FIG. 9 is an enlarged perspective view of a portion of FIG.
8, showing schematically the connection system used to join the
modular components of the FIG. 8 platform system embodiment;
[0044] FIG. 10 depicts in perspective view the modular assembly of
multiple platform subsections to form a platform system in
accordance with an aspect of the present disclosure;
[0045] FIG. 11 depicts in perspective view a deployment assist cart
used in accordance with an aspect of the present disclosure;
and
[0046] FIGS. 12A-12C depict in side elevational view stages of the
erection of the platform system onto a roof using the deployment
assist cart of FIG. 11.
DETAILED DESCRIPTION
[0047] An aspect of the present disclosure addresses the need for a
platform system that allows a worker to construct and maintain
roofs safely and conveniently, including especially the sloped
roofs of greenhouses and like structures that are constructed of
glass or other fragile materials. Embodiments of the platform
system have a configuration that is adaptably sized and can be
placed onto the roof, with the loading supported on appropriate
structural members of the roof system. The platform system can be
configured to permit a worker to easily access specific glass
panels of a greenhouse roof for repair or replacement while
providing a greatly improved level of security and protection.
[0048] Generally stated, embodiments of the present platform system
include one or more of: (i) a platform section comprising a working
surface having an adjustable working length; (ii) a railing system
on one or both sides of the platform that protects a worker from
inadvertently falling off the platform; (iii) support bases that
allow the platform system to be supported with a clearance
maintained between the working surface and the underlying roof; and
(iv) anchorage points to which a worker's fall arrest system can be
reliably secured. The platform system ordinarily is disposed on a
sloped roof with its lower end approximately at the eaves of the
roof and with its length direction extending along a line toward
the roof ridge. It facilitates convenient and immediate access to
any desired area of a roof structure underneath the platform system
or adjacent to it.
[0049] The platform system is described herein with principal
reference to its use in constructing and repairing glass-roofed
greenhouses. However, it will be understood that embodiments of the
platform systems provided herein are equally useful with roofs
constructed with other fragile materials (e.g., slate or terra
cotta tile) not capable of sustaining significant loads by
themselves. More generally, the platform system and the optional
deployment assist cart herein could be used beneficially in any
other situation in which access to a horizontal or sloped area of a
structure is desired but it is preferred, or probably necessary,
that the loading that results be applied only in defined points or
regions outside that immediate horizontal or sloped area.
[0050] The present platform system beneficially includes removable
platform treads. They are ordinarily installed beginning at the
lower end, with the total number of treads being preselected to
provide access and define a working surface that extends just up to
the roof area to be serviced, without obscuring it. Thus, the
platform system provides great flexibility, with the working
surface appointed to allow a worker to walk or crawl to gain access
to the area of interest, and to sit, kneel, or lie close enough to
carry out required activities in that area safely, conveniently,
and comfortably. In an embodiment, the platform area and the
associated platform treads are approximately 30 inches (75 cm) wide
to afford easy passage and positioning of the worker, but other
dimensions are also possible. Although not required, the platform
system is typically constructed in sections that are at least 5
feet (1.5 m) long, but sections constructed in any convenient
length, such as 10, 15, or 20 feet (3, 4.5, or 6 m) or more are
also possible, especially if fabricated with lightweight materials
that facilitate easy handling, as described in more detail
below.
[0051] The terms "horizontal" and "vertical" are used herein to
describe, in the conventional sense of those terms, the orientation
of certain structural members of the present platform system when
it is resting on a level, flat surface. Vertical members are thus
ones that extend in a direction perpendicular to the plane of the
level surface; horizontal members extend parallel to the plane of
the level surface, and include ones oriented along either the
platform length direction (e.g., platform rails 56 and guardrails
58 shown in FIG. 3) or the platform width direction (e.g., platform
treads 78 and horizontal members 60, 61 of FIG. 3). (Of course,
when the platform system is placed on a sloped roof (also termed a
"pitched roof"), the horizontal components that extend along the
platform length direction become inclined at an angle that
generally conforms to the angular pitch of the roof and the
vertical components are oriented in a direction generally
perpendicular to the plane of the roof.)
[0052] The present platform system and the working area provided
thereby are described as elongated, meaning that they extend
horizontally along a platform length direction with a platform
length dimension that is ordinarily greater than a corresponding
horizontal width dimension measured across the platform working
area in a platform width direction perpendicular to the platform
length direction. Hence, the platform system and certain components
thereof are described as having "upper" and "lower" ends, which
refer to the respective ends that are higher and lower in elevation
when the system is disposed with its length extending generally
along a direction between the eaves and the ridge of a sloped roof
structure. Of course, other placements on a roof are also possible.
Unless otherwise specified, "left" and "right" are used in
reference to the sides of the platform system when viewed along the
length direction from the lower end. As used herein, the term
"working area" refers to the area of the present platform system
that is accessible and configured to permit a worker to walk,
stand, sit, kneel, or the like in the ordinary course of using the
system. In general, the working area is provided by removable
platform treads, though there may also be ancillary or peripheral
areas that provide some additional amount of accessible space but
are not covered with removable treads. The "full working area" is
defined as the working area afforded when platform treads are
installed in all available positions between the ends of the
platform rails, whereby worker access is provided along the entire
length of the platform system.
[0053] The present platform system and its various components may
be constructed of any suitable structural materials that afford the
requisite strength and other mechanical properties. Certain
embodiments employ lightweight materials to minimize the loading
imposed on structures on which the platform is situated during its
ordinary use.
[0054] One possible embodiment of the present platform system is
depicted by FIG. 3. Platform system 50 includes a platform section
52, which comprises left and right platform rails 56 that extend
substantially the full length of the platform section, left and
right guardrails 58, upper-end guardrail posts 68, and lower-end
guardrail posts 70. In the embodiment of FIG. 3, the guardrail
posts 68, 70 are attached to platform rails 56 through intervening
structural members included in upper and lower support bases 79,
80. Other configurations that provide attachment of the guardrail
posts to the platform rails, either directly, or indirectly through
intervening members, are also contemplated.
[0055] One or more platform treads 78 span the left and right
platform rails. In the FIG. 3 implementation, the treads are
supported at each side by flanges 57 that project inwardly from the
respective platform rails 56, as also depicted for one possible
embodiment by FIG. 5B. Alternatively, platform rails 56 might be
configured to provide support and anchorage for treads 78 directly.
It is preferred that the platform rails be situated at the left and
right sides of the platform section, with the platform treads
therebetween. However, in other embodiments, the platform rails
might be displaced inwardly from the sides of the platform section,
provided adequate stability can be maintained.
[0056] FIG. 3 depicts the guardrail posts 68, 70 as being vertical
(i.e., perpendicular to the surface of the platform treads). In
other embodiments (not shown), the guardrail posts are angulated,
so that they become approximately vertical with respect to the
ground after the platform system is disposed on a sloped roof.
Guardrails 58 are disposed horizontally at a preselected height
above the surface of platform treads 78 and supported at their ends
by lower and upper guardrail posts 68, 70. Although the guardrails
may be situated at any convenient height, they typically are
positioned in accord with recognized design guidelines or
regulatory standards for worker protection. Ordinarily, the height
is such that each guardrail can function both as a handrail for a
worker traversing the platform system and to inhibit the worker
from falling off the side. The guardrails additionally can provide
sites for anchorage points for worker fall protection equipment, as
described in more detail below.
[0057] The guardrail system in some embodiments of the present
platform system further comprises a sidewall to afford additional
protection, inter alia, by inhibiting a prone worker from rolling
off the side of the platform system through the space between the
working surface and the guardrails. For example, the sidewall may
be provided by screening or by one or more midrails that extend
horizontally from the lower to upper guardrail posts and are
located intermediate the working surface and the guardrail. Other
implementations include optional bracing members in the guardrail
system. For example, and without limitation, the sidewall in the
embodiment of FIG. 3 includes cross braces 66 and middle support
posts 72 that further connect guardrails 58 and platform rails 56.
These bracing members both enhance the structural integrity of the
platform system and help obscure the opening between the platform
surface and guardrails 58 to further inhibit a worker from falling
off the platform system.
[0058] Embodiments may also include toerails located contiguous to
the working area. In the FIG. 3 embodiment, toerails 74 project
perpendicularly upward from platform rails 56 and extend along the
platform length. Toerails enhance safety, both by inhibiting a
worker walking on the platform from stepping off the edge and by
reducing the likelihood that items on the platform surface, such as
tools, equipment, or supplies, would fall from, or be kicked off,
the platform sides. In some embodiments, toerails 74 (as well as
other portions of the structure) include holes (such as holes 76)
to reduce overall platform weight. Toerails may be anchored in any
suitable way, including without limitation direct attachment to
either the guardrail posts, the platform rails, or the treads.
Alternatively, as can be appreciated by reference to FIG. 5B, the
need for separate toerails might be reduced or eliminated by
employing a platform rail 56 that is tall enough above support
flange 57.
[0059] The guardrail system, including the midrails and toerails if
present, extends substantially the platform length, meaning that
the railing coverage along the left and right sides of the platform
system is sufficient to afford fall protection for a worker present
anywhere on the working surface. In most embodiments, the
guardrails extend continuously between guardrail posts that are
attached to the platform rails at or near their respective opposite
ends.
[0060] In some embodiments, the guardrail system is prepared as a
unitary assembly, meaning that each horizontal guardrail and its
associated upper and lower guardrail posts, and possibly other
components, are formed as a single-piece assembly, such as by
welding or otherwise permanently joining multiple components to
form the single piece; by bending a single elongated member at its
ends to form guardrail posts perpendicular to an intermediate
guardrail section; or by any other suitable manufacturing process.
A unitary guardrail assembly may also incorporate midrails, cross
bracing, middle support posts, toerails, or other desired
structural members. Alternatively, separate guardrail and guardrail
post members may be connected in a non-unitary assembly by any
suitable form of mechanical attachment, including, without
limitation, bolted tube and socket connectors.
[0061] The present platform system can readily be equipped with
suitable anchorage points for a personal fall arrest system. Such
systems typically include a body belt or harness fitted to a worker
and tethered by at least one rope, cable, chain, webbing strap, or
the like to a suitable anchorage point. Once in the appointed
working location, the worker attaches the tether to the anchorage
point with a releasable locking clip, such as a carabiner or snap
hook. However, the practical efficacy of any fall arrest system is
completely dependent on having a conveniently positioned and
anchorage point.
[0062] A functioning fall arrest system greatly reduces the
likelihood of a serious injury to a worker from in the event of a
fall, and may allow timely rescue and removal of the worker to
safety. Many industry and governmental standards now require this
or comparable protection for workers at elevated locations.
[0063] Adequate safety protection is particularly challenging for
workers on a glass-panel greenhouse roof. The solid decking of many
conventional roof constructions means a worker ordinarily is in
danger only of falling only at the side or edge, whereas a worker
on a greenhouse roof can also fall through the glass panels, with
the potential of both lacerations from a broken panel and trauma
from hitting structure on the way down and/or the floor or ground
below. Suitable anchorage points readily be established on a
conventional roof, e.g. by attachment to normal structural members
or the roof deck itself, but are ordinarily unavailable or
difficult to access on a glass roof.
[0064] An embodiment of the present platform system provides one or
more anchorages for the tethers of a personal fall arrest system.
Typically, these anchorages can be provided by any structure to
which a locking clip, such as a carabiner or snap hook, can be
removably attached. Ideally, the anchorages are adequate to sustain
the load that might reasonably be expected in a fall or other like
foreseeable emergency. In various embodiments, the anchorages of
the present platform system comprise one or more discrete anchorage
points that provide an aperture configured to render it capable of
engaging a locking clip. Useful forms of such discrete anchorage
points include, without limitation, eyebolts, and secured free
rings having round, oval, d-ring, or other similarly functional
shapes. They may be located at any accessible point. In a
particularly convenient embodiment, the platform system comprises a
plurality of discrete anchorage points disposed along both
guardrails, thereby providing a worker using the platform system
one or more anchorage points located in proximity to the working
area with any possible tread configuration. FIG. 3 depicts a
plurality of discrete anchorage points in the form of
inwardly-projecting eyebolts 59 that are spaced along guardrails
58. Alternatively, anchorage points might be placed on the
toerails, midrails, or platform treads, or at any other suitable
location. Fall arrest systems could also be anchored directly to
the guardrail or to a free rope separately secured at both ends,
e.g. to the guardrails.
[0065] The structural integrity of the platform system shown in
FIG. 3 is even further enhanced by structure at the platform ends,
including upper and lower support bases 79, 80. In a representative
intended use, the platform system is configured to be placed so
that at least its upper support base, and possibly its lower
support base as well, engage load-capable structural members of a
sloped, glass-paneled roof system. The platform system and its full
load are thus situated on the roof and supported so that a
clearance is maintained underneath at least the working area and a
worker has access to glass panels and other elements in a desired
region of the roof structure. In the FIG. 3 configuration, the
support bases 79, 80 respectively comprise upper horizontal member
61 and lower horizontal member 60, which are directly connected to
platform rails 56. In other embodiments, the connection between the
horizontal members and the platform rails is made indirectly
through other intervening members. The FIG. 3 structure further
comprises side braces 62 and gusset braces 64 attached to the
horizontal members 60, 61 and the guardrail posts 68, 70. The
selection, sizing, attachment, and placement of the various end and
side bracing members included in the FIG. 3 embodiment are done in
a manner consistent with the desired capabilities and requisite
strength of the platform system. In various embodiments, the
support bases 79, 80 also include optional upper and/or lower
support pads that extend below the horizontal members, of which
support pads 86, 87 in FIG. 3 are representative.
[0066] FIG. 3 shows the support bases being located at the upper
and lower ends of the platform system, but in other implementations
one or both are located somewhat away from the ends, displaced
along the length direction toward the center by any distance that
still permits adequate stability to be maintained. One such
configuration is depicted by FIG. 10, wherein lower support base 80
is located at the lower end of the platform section, but upper
support base 79 is displaced somewhat below the upper end.
[0067] The lower and upper horizontal members 60, 61 in FIG. 3 are
structured as outriggers that extend laterally to a width greater
than the width of the platform area itself. Increasing the
effective lateral extent of the horizontal members improves the
stability of the platform system against tipping to the side, both
while it is being positioned and when it is in use and supporting
personnel and materiel. Widening the outriggers also distributes
the loading imposed on the roof structure, due to the weight of
both the platform system itself and the personnel and materiel it
carries, over a larger area. However, too high an outrigger span
limits the placement of the platform system near the edge of a
roof, e.g. at the gable end of a typical sloped roof. In the case
of the FIG. 3 embodiment, the effective width at the upper end of
the platform system in use is established by the point at which the
pair of support pads 86 and/or rollers 82 rest on underlying roof
structural members. Optionally, the lateral positioning of the
pairs of support pads relative to the platform system (and thus the
corresponding pad spacing) is adjustable to accommodate different
roof configurations. For example, the point at which support pads
86 are attached to the outrigger portion of upper horizontal member
61, as depicted in FIG. 3, might be made adjustable.
[0068] The present platform system employs platform treads that are
removably secured to the platform rails. For clarity of
illustration, FIG. 3 depicts only two platform treads 78, one
installed onto the platform rails 56 and a second one positioned to
be installed. Treads 78 rest on support flanges 57 that project
inwardly from platform rails 56. It will be understood that any
desired number of platform treads 78 may be installed sequentially
along platform rails 56 to create the requisite access path,
beginning at the lower end of platform section 52 and extending
toward the upper end for a preselected distance. The distance is
selected so that a worker can easily position himself for
convenient access to service a desired section of the roof over or
beside which the platform system is situated. Platform treads 78
are preferably sized to permit the length of the access path to be
selected in convenient increments. Preferably, platform treads 78
are installed with only a minimal gap between adjacent treads to
minimize a tripping hazard for a worker ascending the path and to
prevent tools, supplies, debris, or the like from falling through,
but some amount of gap is possible.
[0069] Any suitable form of tread attachment may be used to
removably secure the platform treads. At least one attachment
should be provided proximate the left and right edges of each
tread, but two or more attachments may be used on each side to
improve the stability and secure positioning of the attachment. In
one simple form, the tread attachment comprises a threaded fastener
system such as a bolt and nut arrangement, with the treads and
platform rails having alignable apertures through which the
fasteners can be passed and secured. Self-aligning arrangements are
preferred for ease of configuration and assembly in the field.
[0070] For example, each platform rail may provide a U-shaped
channel having an inwardly-facing opening sized to accept and
support platform treads of a desired type. In this configuration,
the treads either are slid in from the top or bottom end or are
placed at the requisite level and rotated from an oblique
orientation with respect to the platform length into horizontal
orientation to effect engagement on both sides with the U-channel.
Attachment can also be made using threaded fasteners such as a bolt
and engaging nut or expanding toggles.
[0071] Another tread attachment method (shown in FIG. 4) employs
U-shaped step brackets 102 spaced regularly along flanges 57 of the
opposing platform rails 56 and oriented with their open ends toward
the upper end of the platform system. Suitable treads 78 are
dropped into slots provided by the open ends of step brackets 102.
Apertures 106 in the top portion of each tread 78 are configured to
engage studs 104 upstanding from platform rail 56. FIG. 4 depicts
one tread already in position and a second tread inserted in its
bracket and ready to be lowered over its corresponding stud.
Optionally, studs 104 are threaded, so a nut (not shown) can be
attached after placement of the tread to improve the security of
the attachment. Other arrangements for securing the treads are also
contemplated.
[0072] Still another form of self-aligning tread attachment is
depicted in FIGS. 5A and 5B. For clarity of illustration, FIG. 5A
shows a single attachment point proximate the left edge of
representative treads 78a, 78b, but it will be understood that the
treads are similarly attached on both sides, and preferably at two
or more points on each side, to provide greater stability and
security of attachment. This form is particularly convenient and
reliable, because it permits treads to be installed and removed
quickly and without the need for tools or separate fasteners.
[0073] In the implementation depicted, each platform rail 56
comprises an inwardly-projecting support flange 57 configured to
support the peripheral edges of platform treads 78a, 78b. In FIG.
5A, tread 78b is shown in full engagement, while tread 78a is
depicted as it is being installed, prior to its final engagement in
the position indicated by dotted lines 119.
[0074] Still referring to FIGS. 5A and 5B, a plurality of
upstanding studs 108 are attached at regular intervals along the
support flanges 57 on both sides of the platform. Each stud 108
includes an enlarged, terminal head 110 portion and a
smaller-diameter shank 112 portion. Each platform tread includes a
keyhole-shaped slot 114 having a small-diameter portion 116
extending in the platform length direction upwardly away from
large-diameter portion 118. Slot 114 is configured for locking
engagement with stud 108.
[0075] Head 110 has a diameter such that it can pass through
large-diameter portion 118 but not small-diameter portion 116 of
slot 114, while shank 112 can slide through portion 116. Tread 78a
is shown as being placed so that the large-diameter portion 118 of
its keyhole-shaped slot 114 is oriented toward the lower end of the
platform and with head 110 protruding through slot portion 118.
Thereafter, tread 78a is secured by sliding it downward in the
direction D into the position defined by dotted lines 119, so that
shank 112 becomes located in portion 116. Tread 78b is shown in the
resulting, fully-engaged configuration. FIG. 5B shows in
cross-section the full engagement of a stud 108 in a slot 114.
[0076] The platform treads are fabricated from any suitable
material that provides sufficient strength, stiffness, and
durability. Safety is promoted by a non-slip top surface on the
treads, such as one that is suitably patterned, textured, or
roughened. A gritty surface is especially beneficial for using the
platform system in adverse weather. Metal or wood treads can be
used, but strong, lightweight composite materials beneficially
reduce weight. For example, a lightweight, non-skid platform tread
can be fabricated using a KEVLAR.RTM. para-aramid-carbon fiber
composite.
[0077] Some implementations of the present platform system include
an inclined top platform tread as the uppermost tread. As depicted
in FIG. 7, such an inclined top platform tread 120 is inclined by
an angle .phi. with respect to the platform horizontal direction,
so that when the platform system is erected on a roof sloped upward
by approximately the same angle .phi., the surface 122 of the top
platform tread 120 is approximately parallel to the plane of the
ground and a floor of the greenhouse or like structure. This
surface 122 thereby provides a level area on which a worker can
safely and comfortably stand, kneel, or lie while performing
required tasks. Surface 122 is supported by riser 124, which
extends from base section 126 to surface 122. The same attachment
means used to secure the running platform treads can also be used
to secure the inclined top platform tread to the platform rails at
the desired point along its length. For example, the FIG. 7
configuration is shown with keyhole-shaped slots 114 of the same
type as seen in FIGS. 5A and 5B. It is preferred, but not required,
that an inclined top platform tread be longer than the remaining
platform treads 78 so that its flat surface 122 is large enough so
that a worker can safely stand, sit, or kneel thereon.
[0078] In another variant, some or all of the running platform
treads may have an inclined configuration, so that the platform has
the general appearance of a staircase and the platform treads
function as stair steps on which the worker can ascend to the
desired level, instead of walking up on an inclined, but generally
planar, platform path.
[0079] The present platform system is appointed to be supported
over a roof system in a manner that permits it to be used by a
worker servicing an area of the roof beneath. Typically, one or
both of the ends of the system are configured so that they may bear
on capable structural members of the roof, such as the purlins
depicted in FIGS. 1-2. Optionally, the lower end may be configured
to engage either structure at the eaves 19 of roof side 12, if
available, or, alternatively, a ladder or scaffold or the like
positioned next to side wall 20, e.g. an engagement effected using
one or more clamps.
[0080] For example, the lower end of the FIG. 3 embodiment includes
clamps 77 attached to the platform system, e.g., to lower
horizontal member 60. Clamps 77 are configured to engage structure
that may be available at the eaves of some greenhouses. The upper
end includes upper support pads 86 that project downwardly from the
upper horizontal member 61. Together clamps 77 and upper support
pads 86 permit platform system 50 to be secured with its lower end
at the eaves and to extend upwardly along the greenhouse roof with
at least its upper support base bearing on the roof's structural
members. The platform system is thereby supported, so that a slight
clearance is maintained between it and the underlying roof. Thus, a
worker is enabled to access a desired portion of the greenhouse
roof for construction, maintenance, repair, or like operations. It
will be understood that clamps 77 may be configured in any form
needed to ensure a secure connection to available support
structure, whether part of the greenhouse structure itself, an
independent scaffold, the deployment assist cart discussed below,
or other like structure. Preferably, clamps 77 are attached to the
platform system by any suitable removable connection, such as
bolts, to make the system more versatile.
[0081] The present platform system optionally, but preferably,
includes one or more retractable roller assemblies that facilitate
rolling it into a desired position on a roof surface. The roller
assemblies ordinarily provide for rolling motion along the platform
length direction, but may permit lateral motion also. Various
configurations are possible for the rollers, consistent with
maneuverability and stability of the platform system.
[0082] In an implementation, the roller assembly comprises one or
more retractable rollers having a retracted position and an
extended position. The roller assembly is configured such that when
the platform system is disposed on a roof structure with the
rollers in the retracted position, at least one support base is in
contact with the roof structure and the body of the platform system
remains elevated above the roof structure; in the extended
position, the rollers are in contact with the roof structure and
bear against structural members (e.g., at least two of the glazing
bars 32 shown in FIG. 2) and not the glass portion. In an
embodiment, the design is such that the platform system is stable
against tilting while it is being moved.
[0083] For example, the exemplary embodiment of FIG. 3 provides a
roller assembly that incorporates rollers 82 associated with both
upper support pads 86. With these rollers 82 thus situated on its
left and right sides, platform system 50 can readily be manipulated
into position and thereafter stably secured by attaching clamps 77
to suitable support structure at its lower end and retracting
rollers 82 to bring upper support pads 86 into contact with
structural members of the roof. FIGS. 6A-6B (discussed in more
detail below) depict one possible type of roller assembly.
[0084] As noted above, some greenhouses do not include structural
members at the eaves to which the lower end of the present platform
system can be secured. In such configurations, the lower end of the
system can be secured to an external, temporary support such as a
ladder, scaffold, or the deployment assist cart described below.
Alternatively, the system can be configured with a lower support
base 80 intended (like the upper support base 79) to rest on the
roof itself. Such embodiments preferably include lower support pads
and one or more rollers associated therewith, which are similar to
upper support pads 86 and upper rollers 82. Of course, the platform
system can employ both a lower support base and any suitable
anchorage to an external support for added security.
[0085] Some roller assembly implementations employ a single,
relatively wide roller at one or both ends of the platform system.
For example, such a roller may extend laterally to at least the
full width of the system, and preferably wider, so that the
platform system itself is stable against tipping laterally and can
be moved readily. Alternatively, at least two rollers, such as
separate rollers included at both sides on of the one or both ends,
are configured to provide similar stability.
[0086] In the FIG. 3 configuration, both the rollers 82 and upper
support pads 86 to which they are attached are laterally displaced
from the main platform area and deployed on outriggers. As
indicated above, this spacing beneficially improves stability
against tipping, both when moving the system and when it is
supporting a worker during its intended use. Ideally, the one or
more rollers on each side are sufficiently wide to be able to
engage structural members whose spacing can vary widely between
different roof designs. Alternatively, the lateral span between the
rollers in a multi-roller configuration is adjustable. FIG. 3
depicts rollers 82 and upper support pads 86 as being conjoined and
thus in close proximity, so they can both engage the same roof
support structure. In other arrangements, the two need not be
attached, and may be separated and adapted to engage different
structural members. It is also contemplated that the lateral
spacing of one or both of the rollers and support pads may be
adjustable.
[0087] In any of these embodiments, each roller is ordinarily
rotated on an axle supported at one or, preferably, both ends. In
some implementations, the axle is supported by a fork having two
prongs dependent from a central strut, with the ends of the axle
attached to the respective prongs. Alternatively, one, or
preferably both, ends of the axle are supported by independent
struts. It is preferred, but not required, that the axle be in a
fixed orientation along the width direction of the platform
system.
[0088] A variety of actuation mechanisms can be employed to move
the rollers between the extended and the retracted positions. In
one option, the axle support mechanism is hingedly connected to
some member of the platform structure, so that the roller assembly
can be moved between the extended position and the retracted
position. Various hinging arrangements are possible, including ones
in which the roller assembly can be tilted downwardly from, and
along the length of, the platform system (e.g., from a horizontal
base member), or outwardly (e.g., from the platform rails). In
another option, a lead screw or gear arrangement can be used to
drive the axle support mechanism between the extended and retracted
positions.
[0089] In still another option, the actuation relies on a spring
mechanism associated with each roller. The spring mechanism urges
the roller into the extended position, and may include a latching
arrangement permitting the rollers to be locked in either or both
of the extended and retracted positions. In other embodiments, the
spring mechanism has a compliance such that imposing at least a
predetermined weight on the platform system is sufficient to
overcome the urging into the extended position and drive the
rollers into the retracted position. Typically, the predetermined
weight is some appreciable fraction of the expected weight of a
worker, so that the rollers of an unloaded platform system are
extended, but reliably move into retracted position once a worker
mounts the platform.
[0090] FIGS. 6A-6B depict one such roller assembly, wherein a
roller (with an associated spring mechanism) is associated with a
support pad 86. The FIG. 6 arrangement can be used with the
platform system embodiment of FIG. 3 or other embodiments. Roller
82 is disposed for rotation on an axle 84, whose opposite ends are
attached to struts 88, which are supported and vertically movable
through collinear mating holes 90 in upper and lower axle mounts
92, 93. Upward movement of strut 88 is countered by a compliant
member, such as spring 94 compressed between upper axle mount 92
and spring mount 95 attached to strut 88. The spring constant of
springs 94 is selected so that loading of the platform system with
more than a predetermined weight overcomes the downward urging of
rollers 82 by springs 94, so that support pads 86 rest on the
underlying roof structure. FIG. 6B shows roller 82 in its extended
position below the bottom of upper support pad 86, while FIG. 6A
shows roller 82 in its retracted position, with spring 94
compressed and strut 88 moved upward from the FIG. 6A
configuration.
[0091] In a related embodiment (not shown), a retractable roller
assembly such as that of FIGS. 6A-6B is associated with one of the
support bases, while the other support base includes one or more
non-retractable rollers. For example, platform system 50 of FIG. 3
might be modified to have retractable roller assemblies of the FIG.
6 type attached to support pads 86 on both sides of upper support
base 79, but rollers fixed in an extended position on support pads
87 of lower support base 80, along with clamps 77 as shown. In use,
this form of the platform system could rely on being clamped at the
roof eaves. Thus, the load of the platform system would be
distributed, with some carried through the upper support pads 86
and the rest through the clamping of the lower end.
[0092] In the embodiment depicted in FIG. 3, the upper and lower
support bases 79, 80 are permanently connected to platform section
52. In an alternative construction, the system is modularized,
meaning that it is configured to be assembled from a kit comprising
a plurality of subcomponents and disassembled again at will, such
as on a job site. The mating subcomponents that are to be connected
during the assembly are joined in any convenient but secure and
reversible manner.
[0093] One possible modularized implementation is shown in FIG. 8,
wherein upper and lower end assemblies 98, 99 are separably joined
to the platform section 100 (which includes platform rails 56,
guardrails 58, treads 78, and associated bracing components) by any
form of secure, locking connection, such as a pin and socket
attachment. In this implementation, end assemblies 98, 99 comprise
support bases 79, 80, which also include horizontal members 60, 61
and optional support pads and roller assemblies that are operable
in a manner that is apparent from FIGS. 3 and 6. Respective
guardrail posts 68, 70 are also incorporated in end assemblies 98,
99. The end assemblies are formed by joining together the various
components by any suitable means providing adequate structural
integrity. In alternative modularized configurations, the guardrail
posts are instead included as part of the platform section.
[0094] The locking connection is provided by connector arrangements
that are disposed at each point of engagement between the end
assemblies and the guardrails and platform rails. The FIG. 8
implementation provides four points of engagement at each end of
the platform system, i.e., two at the engagement between the
respective left and right guardrails 58 and the respective
guardrail posts 68 and 70 and two at the engagement between the
left and right platform rails 56 and the horizontal members 60 and
61.
[0095] Generally stated, each connector arrangement comprises a
first connector element attached to an end of the respective
platform rail or guardrail, a second connector element attached to
a respective one of the end assemblies, and a locking means.
Typically, one of the connector elements is a connector pin; the
other connector element is a socket having a complementary, mating
shape adapted to receive the connector pin. The first and second
connector elements are configured to be joined in mating
relationship, with a locking pin securing the mutual engagement of
the elements.
[0096] The detailed view of FIG. 9 representatively depicts one
suitable form of the connector arrangement with reference to the
joint at the top of right upper guardrail post 68 in FIG. 8.
Guardrail connector pin 96a projects horizontally from upper
guardrail post 68 and is configured to be received in socket 96b in
guardrail 58. After the components are assembled, a through
aperture is formed by aligned apertures 96d in guardrail 58 and 96e
in connector pin 96a. The locking engagement is completed by
passing locking pin 96c through these aligned apertures in a
direction perpendicular to the commonly aligned axes of pin 96a and
socket 96b. In an alternative locking arrangement, connector pin
96a might include a spring-loaded pin adapted to project
transversely from the pin axis to engage an aperture, as depicted
at 96d, in socket 96b.
[0097] Similar locking connections are made at each of points of
engagement seen in FIG. 8, wherein guardrail connector pins 96a
attached to guardrail posts 68, 70 are adapted to be received in
corresponding sockets 96b provided in guardrails 58 and platform
rail connector pins 97a (also attached to guardrail posts 68, 70)
are adapted to be received in corresponding sockets 97b provided in
platform rails 56. Each connection is secured by locking pins (not
depicted in FIG. 8). Preferably, each of the locking pins is
further secured in position by any suitable means known to a
skilled designer, including without limitation a cotter pin or by
using a threaded form of locking pin secured by a mating nut.
[0098] Locking engagements of the respective platform frame
elements are readily implemented by using tubular members having
round or rectangular internal passages to construct the guardrails
and platform rails, with the connecting pins being of complementary
size and shape. Other implementations are also suitable, including
without limitation ones in which the respective disposition of the
connector pins and sockets on the rails and end assemblies is
reversed. In still another alternative, pins 96a and 97a are
omitted and instead, sockets on the end assemblies are configured
to directly receive the guardrails and platform rails with a
locking connection.
[0099] The modular system of FIG. 8 can easily be disassembled into
its component subassemblies (e.g., end assemblies 98, 99; two side
sections, each comprising a platform rail 56, a guardrail 58, cross
braces 66, and middle support posts 72; and a requisite number of
platform treads 78, along with needed hardware). Disassembly
greatly reduces the bulkiness of the platform system for
transportation and storage before subsequent re-use. In addition,
the platform section can be used fitted with different forms of the
end sections that are adapted to different greenhouse
constructions.
[0100] In most modularized embodiments it is not intended that the
components within the end assemblies be disassembled during
ordinary operation of the platform system. Hence, the techniques
used to assemble the end-assembly components can include welding,
gluing, or other permanent methods, as well as other less permanent
joining methods such as bolting the components together to permit
repair or replacement of damaged parts. The guardrail and bracing
elements of each side rail are ordinarily not intended for routine
disassembly, and so are joined by similar methods.
[0101] In a further aspect, the modular concept of the FIG. 8
embodiment can be extended to provide platform systems of varying
lengths by connecting multiple subsections. One representative
embodiment is depicted generally in FIG. 10, wherein the platform
section is divided into two subsections 100a, 100b. Specifically,
the platform rails 56 and guardrails 58 shown in FIGS. 3 and 8 are
divided into platform rail subsections 56a, 56b and guardrail
subsections 58a, 58b that are connected through coupling support
assembly 130, which has a configuration with features generally
similar to those of end assemblies 98, 99 shown in FIG. 8. Assembly
130 comprises: a middle support base 132 having a middle horizontal
member 134 and middle support pads 136 depending downward
therefrom; left and right middle guardrail posts 138 connected to
middle support base 132; and connector arrangements at the top and
bottom of the left and right middle guardrail posts that secure the
facing platform rail and guardrail subsections in collinear
relationship. As depicted, the individual connector pins 96a of
FIGS. 8 and 9 are replaced by pairs of oppositely directed
connector pins 140a configured to engage mating sockets 140b in the
facing ends of the platform rail subsections 56a, 56b; likewise
connector pins 97a are replaced by pairs of oppositely directed
connector pins 141a configured to engage mating sockets 140b in the
facing ends of guardrail subsections 58a, 58b. The connections
effected using these mating pins 140a, 141a and sockets 140b, 141b
join the platform rail and guardrail subsections together
collinearly in a secure, locking connection to form the respective
platform rails and guardrails. However, intermediate connector
arrangements that lack any one or more of these components are also
contemplated, as long as they provide a secure connection between
the platform rail subsections of the respective platform
subassemblies and ensure that a secure and adequately supported
guardrail system protects the entire platform. For example, the
middle support base might be omitted, with pins alone used to join
subsections 100a and 100b. The FIG. 10 embodiment optionally
includes roller assemblies (not shown) associated with each of the
support assemblies. The roller assemblies may be of the type
depicted in FIGS. 6A-6B or other suitable design.
[0102] Implementations such as that of FIG. 10 beneficially
facilitate the servicing of large greenhouses, because the platform
system can be erected on the roof in stages, instead of having to
lift an entire system into final position in a single operation.
For example, two platform subsections (e.g. subsections 100a, 100b
seen in FIG. 10) might be needed to provide adequate length. Such a
platform system can be erected by first placing onto the roof at
the eaves a first subassembly comprising upper end assembly 98,
platform subsection 100a, and coupling support section 130. Then a
second subassembly comprising platform subsection 100b and lower
end assembly 99 can be lifted to the eaves and coupled onto the
first. The combined subassemblies can then be rolled up the roof
till the lower end assembly 99 reaches the eaves and is secured to
the desired support structure associated therewith. Modular
platform systems comprising more than two subsections are also
contemplated herein. Use of individual subsections that are as long
as possible, consistent with a handleable weight, is generally
beneficial, since the number of joints can be minimized and the
overall structure is more rigid and less subject to flexure at each
joint.
[0103] In a still further aspect of the present disclosure, a
deployment assist cart is used in conjunction with the platform
system to provide a platform erection system. Such a cart may be
used to facilitate the erection of the platform system onto a
greenhouse roof. The cart may include wheels or tracks, so it can
be moved to a desired site adjacent to a roof structure to be
serviced. Preferably the cart is also used to transport the
platform system components. It optionally provides a stable and
secure attachment for the lower end of the platform system, since
many greenhouses do not have a suitable structure to which the
lower end can be secured.
[0104] FIG. 11 depicts a representative embodiment, including cart
160 having wheels 162 that permit it to be easily maneuvered and
locked into a convenient position. Once the cart is positioned,
outrigger stabilizers 164 are projected downwardly, e.g. by a
reversible jackscrew mechanism (not shown), so that the weight of
the cart and whatever load it supports are transferred off the
wheels and onto support pads 165 of stabilizers 164. Cart 160 is
optionally provided with suitable handles to permit it to be
maneuvered into position by a worker. Alternatively the cart may be
transported by attaching it to a vehicle through a hitch (not
shown).
[0105] Cart 160 is equipped with deployment support 168, which
upstands from platform base section 169, and ordinarily is braced
either by an optional access ladder 166 as shown in FIG. 11 or by
other suitable bracing structure. Support 168 may be oriented
either exactly perpendicular to base section 169 or at a
preselected angle away from the vertical direction. In the FIG. 11
embodiment, access ladder 166 and deployment support 168 are
stabilized by securing their respective bases to the platform base
section 169 of cart 160 and joining them at a point above the
platform base section, preferably at or near their tops.
Optionally, access ladder 166 and deployment support 168 are
removable for ease of transport. In another variant (not shown),
ladder steps are incorporated directly in deployment support 168,
so a separate access ladder is not needed. Deployment support 168
may also include clamps or other like fixturing to provide stable
and secure anchorage for the lower end of the platform system after
it has been deployed on a roof, as mentioned above.
[0106] Cart 160 further includes deployment rails configured to
facilitate the erection of the platform on a roof. In a
representative use, the cart is first positioned at the desired
location. Then the platform system is staged on the deployment
rails and thereafter deployed onto the adjacent roof. The entire
system may be erected in one operation; alternatively, sections of
a modular system may be positioned in a series of steps. The rails
beneficially may be equipped with rollers, guides, slides, or the
like that engage the platform components while they are being
erected. (For clarity of illustration, the deployment rails are
omitted from FIG. 11.) It is preferred that the deployment rails,
if present, be tiltable, but embodiments wherein the rails are
fixed at an inclination angle suitable for positioning the platform
system are also possible. The cart and deployment rails may include
a winch, hydraulics, or other like actuation system to assist in
elevating the deployment rails and/or sliding the platform system
onto the roof structure.
[0107] Referring now to FIGS. 12A-12C, the stages of a
representative and typical use of deployment assist cart 160 are
depicted. For convenience of illustration, the cart is shown as
being used to erect a single-section platform system, such as the
embodiment 50 depicted by FIG. 3, on a sloped greenhouse roof
surface 12. A pair of tiltable deployment rails 170 are rotatably
articulated at or near the top of deployment support 168. In some
embodiments, the point of articulation of rails 170 and/or the
height of deployment support 168 can be adjusted. The articulation
permits the rails to be elevated between a loading position 171a
and a deployment position 171b (shown by dot-dash lines in FIG.
12A). A suitable mechanism (not shown) is preferably provided to
permit the deployment rails to be locked at one or more requisite
elevations.
[0108] In a first configuration shown in FIG. 12A, cart 160 is
situated on the ground near the eaves 19 where the platform is to
be erected, the cart being secured by deploying its outrigger
stabilizers 164. Platform section 50 is placed against rails 170 in
loading position 171a. Then rails 170 and platform section 50
secured thereon are rotated downwardly to an elevation
approximately parallel to the plane of the sloped roof, e.g. to
deployment position 171b, with the top ends of the rails possibly
resting upon the eaves (FIG. 12B). Platform section 50 is then
maneuvered, e.g. by sliding or rolling it upward on rails 170 and
onto the roof structure (FIG. 12C). Once in place, platform section
50 is secured, e.g. by clamping its lower end to either part of the
roof structure at or near eaves 19 or to any convenient structural
member of cart 160. A worker may ascend ladder 166 to access the
platform structure. If needed, a gangplank can be used to bridge
any gap between the ladder and the platform itself.
[0109] Alternatively, the rails 170 might be disposed initially in
deployment position 171b and then platform section 50 placed
thereon, bypassing the rotation connecting the FIGS. 12A and 12B
configurations.
[0110] It will be apparent that the cart embodiment seen in FIGS.
11 and 12 can also be used to erect a multi-section platform system
by a sequence of steps, wherein separated subassemblies of the
platform system are elevated one by one and assembled as they are
moved into position on the roof. For example, the first subassembly
100a of FIG. 10 can be erected in a manner comparable to that
described above, by sliding it up rails 170 and temporarily
securing it on the roof so that coupling support section 130 is
proximate the eaves. Then rails 170 are rotated back to loading
position 171a to receive a second subassembly comprising platform
subsection 100b and lower end assembly 99. The rails are then
raised again into deployment position 171b, along with the second
subassembly, which is joined onto the first subassembly using the
connector arrangements associated with coupling support section
130. The combined subsections can then be slid upwardly into
position on the roof, with the bottom end of the second subassembly
being secured either to structure at the eaves or to a
ground-positioned support such as vertical ladder support 168 or
other structural member of cart 160, or to a conventional
ground-situated ladder, scaffold, or the like. A similar process
can be used to erect a platform having more than two subassemblies
by sequentially repeating pertinent ones of the foregoing steps.
The platform may be removed by reversing the foregoing steps.
[0111] It is desirable that the platform system be strong enough to
accommodate the weight of a single worker and a desired payload of
tools, equipment, and supplies needed for typical maintenance or
repair operations. However, it is further preferred that the
platform system be strong enough to support a second person, for
example to assist or rescue the first worker in an emergency
situation.
[0112] In certain embodiments, the present platform system
beneficially has a strong but lightweight construction. Minimizing
the platform's weight makes it easy to transport, assemble, and
situate on a roof, while also reducing the load that is imposed
onto the roof system during its use. Ideally the platform weight is
a small fraction of the aggregate weight of a worker and their
payload. It is further desirable that a platform system be light
enough that a small work crew can readily erect and maneuver it
into position, all without damaging a glass roof. Systems that can
be handled by a two-person crew are beneficial, especially if the
platform system can be erected on the roof without a crane or an
elaborate or specialized hoist system.
[0113] In an embodiment, a platform system in accordance with the
present disclosure is constructed with materials having high
specific strength and stiffness. These characteristics are most
readily attained with advanced composite materials, however it is
to be understood that any structural material (e.g. metals) can
also be employed in one or more components of low-weight
embodiments. Suitable light-weight materials include, without
limitation, composites with one or more of glass, carbon, or other
polymers or polymeric fibers. Embodiments fabricated with members
composed of a composite with KEVLAR.RTM. para-aramid/carbon fiber
reinforcement in an epoxy matrix provide a beneficial combination
of the required high specific strength and stiffness. Such
composites can be manufactured in various shapes useful in
constructing the present system, including without limitation
round, square, and rectangular tubular forms and flat, planar
panels. The various components can be joined using any suitable
technique or joint hardware.
[0114] Certain embodiments of the present platform system are
capable of supporting a rated load of at least 500 pounds or 200 kg
while being light-weight. Such a platform system having an unloaded
weight "W" (i.e., including a complete set of platform treads but
excluding workers and other payloads) and a full platform working
area "A" is considered to be light-weight if a value of the ratio
W/A is at most 3, 4, 5, 6, 7, 8, 9, or 10 pounds per square foot of
working area.
[0115] The load of the platform system and its payload is supported
over a roof area that may be larger than the platform working area,
particularly for embodiments wherein the support bases include
outrigger supports. The effective support area is at least as large
as the area of a polygon having vertices defined by each of the
points on which the platform system rests atop a roof or like
structure. For example, the configuration depicted by FIG. 3 may be
supported over a rectangular effective support area defined by the
four support pads 86, 87. Alternatively, if the FIG. 3
configuration is clamped at its bottom end by clamps 77 attached to
a rail structure (not shown) at the eaves of a greenhouse, the
effective support area might be defined by a trapezoid having
vertices at clamps 77 and upper support pads 86.
[0116] For example, a representative platform system embodiment of
the form depicted by FIG. 3 might have a full working area 16 feet
(.about.4.9 m) long and 30 inches (.about.75 cm) wide and be
supported by upper and lower support bases that are located at the
platform system's upper and lower ends and have outriggers that
extend to a width of 10 feet (.about.3 m). Such an embodiment can
be constructed with KEVLAR.RTM. para-aramid/carbon fiber reinforced
composite members and platform treads, and be strong enough to
support a rated load of at least 500 pounds (.about.227 kg or 2230
N). Platform treads spanning the 30 inch platform width and
extending about 12 inches (.about.30 cm) along the platform length
would weigh about 4 pounds (.about.1.8 kg or 17.8 N) each. This
platform system, with a full set of platform treads installed along
its length, would have a total weight of about 230 pounds
(.about.104 kg or 1023 N), corresponding to about 5.75 pounds per
square foot of working area (275 N/m.sup.2).
[0117] The 230 pound weight of the platform system and treads of
this embodiment is supported over an effective support area on the
roof of 160 square feet (10 foot outrigger span.times.16 foot
length), corresponding to an effective roof loading of about 1.44
pounds per square foot (69 N/m.sup.2) of effective support area.
Even with a worker, tools, and materiel, the system thus imposes a
roof loading far less than the building code requirement that a
greenhouse in the Delaware location of the inventors must be
capable of withstanding a snow loading of 20-25 pounds per square
foot (.about.958-1197 N/m.sup.2). In representative embodiments,
the present platform system, including a full set of platform
treads but without a user or any other payload, imposes an
effective roof loading of at most 1.2, 1.4, 1.6, 1.8, 2, or 2.5
pounds per square foot of effective roof support area.
[0118] It is noted that design standards in the ladder and scaffold
industries typically presume a safety factor of at least 5, meaning
the device would be presumed able to withstand a loading of five
times the rated nameplate load. The safety factor thus accounts for
variations in strength of the actual device as constructed and
possibly degraded during its lifetime and the need to support an
additional worker who may be forced to aid the primary user in the
event of an injury, medical emergency, fire, or other unforeseen
circumstance.
[0119] Having thus described various embodiments of the invention
in rather full detail, it will be understood that this detail need
not be strictly adhered to but that further changes and
modifications may suggest themselves to one skilled in the art, all
falling within the scope of the invention as defined by the
subjoined claims. For example, certain materials are identified
herein as suitable for constructing components of the present
platform system, but other materials known to a skilled artisan may
also be used. Various structural configurations and assembly
methods that are suitable are also known to the artisan.
[0120] In this specification, unless explicitly stated otherwise or
indicated to the contrary by the context of usage, where an
embodiment of the subject matter hereof is stated or described as
comprising, including, containing, having, being composed of, or
being constituted by or of certain features or elements, one or
more features or elements in addition to those explicitly stated or
described may be present in the embodiment. An alternative
embodiment of the subject matter hereof, however, may be stated or
described as consisting essentially of certain features or
elements, in which embodiment features or elements that would
materially alter the principle of operation or the distinguishing
characteristics of the embodiment are not present therein. A
further alternative embodiment of the subject matter hereof may be
stated or described as consisting of certain features or elements,
in which embodiment, or in insubstantial variations thereof, only
the features or elements specifically stated or described are
present. Additionally, the term "comprising" is intended to include
examples encompassed by the terms "consisting essentially of" and
"consisting of." Similarly, the term "consisting essentially of" is
intended to include examples encompassed by the term "consisting
of."
[0121] When any amount or other value or parameter is given as
either a range, preferred range, or a list of upper preferable
values and lower preferable values, this is to be understood as
specifically disclosing all ranges formed from any pair of any
upper range limit or preferred value and any lower range limit or
preferred value, regardless of whether ranges are separately
disclosed. Where a range of numerical values is recited herein,
unless otherwise stated, the range is intended to include the
endpoints thereof, and all integers and fractions within the range.
It is not intended that the scope of the invention be limited to
the specific values recited when defining a range.
[0122] In this specification, unless explicitly stated otherwise or
indicated to the contrary by the context of usage, amounts, sizes,
ranges, formulations, parameters, and other quantities and
characteristics recited herein, particularly when modified by the
term "about", may but need not be exact, and may also be
approximate and/or larger or smaller (as desired) than stated,
reflecting tolerances, conversion factors, rounding off,
measurement error, and the like, as well as the inclusion within a
stated value of those values outside it that have, within the
context of this invention, functional and/or operable equivalence
to the stated value.
* * * * *