U.S. patent number 3,752,261 [Application Number 05/155,076] was granted by the patent office on 1973-08-14 for multi-stage lift.
Invention is credited to Sherman W. Bushnell, Jr..
United States Patent |
3,752,261 |
Bushnell, Jr. |
August 14, 1973 |
MULTI-STAGE LIFT
Abstract
A multi-stage lift that is portable, compact, lightweight and
easily handled like a hand truck, and yet is stable at relatively
high extensions by virtue of a special outrigger system, three
multi-stage telescopic cylinder units arranged and interconnected
in a unique manner to operate in unison, and a working platform
with a drop-down guard rail assembly.
Inventors: |
Bushnell, Jr.; Sherman W.
(Seattle, WA) |
Family
ID: |
22554036 |
Appl.
No.: |
05/155,076 |
Filed: |
June 21, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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889235 |
Oct 30, 1969 |
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Current U.S.
Class: |
182/17; 182/115;
182/113; 182/141; 182/69.4 |
Current CPC
Class: |
E04G
1/22 (20130101) |
Current International
Class: |
E04G
1/22 (20060101); E04G 1/18 (20060101); E04g
001/22 () |
Field of
Search: |
;182/17,16,63,141,148,115 ;52/632,115,637,638,648 ;280/15C
;187/9 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Machado; Reinaldo P.
Parent Case Text
This application is a continuation-in-part of my copending
application, Ser. No. 889,235; filed Dec. 30, 1969 and now
abandoned.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A portable hoisting device comprising;
a base assembly having ground support wheels collectively defining
a first ground support contact plane,
a plurality of outrigger mounting means spaced about the periphery
of said base assembly,
a plurality of outriggers operatively associated with said mounting
means and having ground support wheels near their outer ends
collectively defining a second ground support contact plane lower
than said first plane when the outriggers are in operative position
whereby said wheels on the base assembly are raised out of ground
contact when the outriggers are in operation, said outriggers being
adapted to be selectively moved out of said operative position to
move their ground support wheels above said first plane whereby the
hoisting device is then supported by the ground support wheels of
the base assembly,
a hoist assembly mounted on the base assembly,
and a work platform carried by the hoist assembly to be raised and
lowered thereby.
2. A portable hoisting device according to claim 1 in which
leveling jack means are selectively operatively associated with the
outer end portions of said outriggers.
3. A portable hoisting device according to claim 1 in which jack
means are operatively associated with opposite sides of said base
asembly for selectively raising the respective side to a height
whereat adjacent outriggers can be placed in operative
position.
4. A lift device according to claim 3 in which said guard rail
assembly includes top guard rails fixed to the upper ends of said
posts and arranged to rest on said intermediate guard rails when
the posts are in lowered storage position.
5. A portable hoisting device according to claim 1 in which said
mounting means comprises elongated slide sockets and said
outriggers are adapted to be slidably plugged into said
sockets.
6. A portable hoisting device according to claim 1 in which said
base assembly is generally rectangular in plan view and said
mounting means comprises four elongated slide sockets extending in
generally diagonal directions inwardly from the corners of the base
assembly, and in which said outriggers are adapted to be slidably
plugged into said sockets.
7. A portable hoisting device according to claim 6 in which a pair
of elongated slide sockets are located at one end of said base
assembly and extend in opposite lateral directions whereby said one
end can be placed against a wall or obstruction with the outriggers
at that end fitted in said pair of sockets rather than in the
diagonal sockets at that end.
8. A portable hoisting device comprising,
a hand truck including a ladder with handles near the top thereof
and ground support wheels near the bottom thereof providing ground
support when the hand truck is tilted rearwardly,
a base frame assembly supported at the forward side of the hand
truck and having ground support means arranged to be raised from
ground contact when the hand truck is tilted rearwardly,
three upright multi-stage gas-operated telescopic cylinder hoists
mounted on the base frame assembly in a triangular arrangement in
plan view with two of said hoists located adjacent opposite lateral
sides of the hand truck and having their bottom stages partly
braced by the ladder and with the third hoist spaced directly
forward from the lateral center of the hand truck and having its
bottom stage rigidly interconnected with the bottom stages of said
two hoists,
a work platform carried by said three hoists to be raised and
lowered thereby, said platform having a lowered position adjacent
the top of said ladder when the hoists are retracted,
means for selectively extending and retracting said hoists in
unison,
and a plurality of outrigger means spaced about the periphery of
the base frame assembly and arranged to be selectively moved into
and out of ground engaging position.
9. A portable hoisting device according to claim 8 in which said
three hoists each have a plurality of telescopic stages
intermediate a bottom stationary stage mounted on the base frame
assembly and a top stage connected to the work platform, said means
for selectively extending and retracting said hoists in unison
comprising respective horizontal coplanar brace means
interconnecting the upper end of the three cylinders of each said
intermediate stage, said horizontal brace means being the sole
means interconnecting said intermediate stages between the top of
the bottom stationary stage and the work platform.
10. A portable hoisting device according to claim 8 in which said
outrigger means have ground support wheels near their outer ends
which take the entire load of the hoisting device when such wheels
are in ground engaging position.
11. A portable hoisting device comprising,
a portable base assembly,
three upright parallel multi-stage gas-operated telescopic cylinder
hoist units in equally spaced relationship from one another and
having their bottom stages rigidly interconnected and mounted on
the base assembly,
a work platform mounted on the top stages of the hoist units, said
hoists each having a respective plurality of telescopic cylinder
stages intermediate said bottom stages and said work platform, said
intermediate stages and said top stages being arranged and adapted
to be extended solely by compressed gas,
a respective collar on the upper end of each such intermediate
cylinder stage,
respective brace means at each intermediate stage interconnecting
the respective collars, said brace means for the intermediate
stages being arranged to stack between the bottom stages and the
working platform when the hoisting device is in lowered position
and to provide the bracing for the intermediate stages when the
hoisting device is in raised position, the brace means for each
intermediate stage comprises three braces arranged generally in an
equilateral triangle in plan view with each such brace having two
longitudinal overlapping parts and means for fastening said
overlapping parts together whereby the overall length of said
braces can be set during assembly so that the brace means will not
exert lateral forces on the intermediate cylinder stages when they
are extended without the work platform being loaded.
12. A portable hoisting device according to claim 11 in which said
three telescopic cylinder hoist units have their extending
cylinders formed of lightweight thin-walled tubing on the upper end
of which the respective collar is mounted, said braces providing
the sole lateral support for said intermediate stages between their
telescopic connections with the top and bottom stages.
13. A portable hoisting device comprising a portable base assembly
including a base frame of generally rectangular outline in plan
view having four slide socket members extending inwardly in
generally diagonal directions from open outer ends at the corners
of the base frame and having frame members rigidly interconnecting
said socket members adjacent their said open ends, said socket
members also being rigidly interconnected in inwardly spaced
relation from said frame members for giving added support to the
socket members and contributing to rigidity of the base frame,
four elongated outriggers adapted to be slidably plugged into the
open ends of said socket members,
an upright hoist assembly mounted on the base frame,
a work platform carried by the hoist assembly to be raised and
lowered thereby,
and ground support wheels on the base assembly for transporting the
hoisting device when the outriggers are not plugged into the socket
members.
14. A portable hoisting device comprising,
a base assembly presenting a plurality of outwardly opening slide
sockets spaced about its periphery and having transport wheels,
a hoist assembly mounted on the base assembly,
a work platform carried by the hoist assembly to be raised and
lowered thereby,
and a plurality of outriggers adapted to be slidably plugged into
said sockets, said base assembly having a plurality of ground
support means collectively defining a first ground support contact
plane, and said outriggers having ground support wheels near their
outer ends collectively defining a second ground support contact
plane lower than said first plane when the outriggers are in
operative position whereby said ground wheels support means on the
base assembly are raised out of ground contact when the outriggers
are in operation.
15. A hoisting device according to claim 14 in which said base
assembly has jack means for selectively raising the sockets of said
base assembly and said ground support means sufficiently to permit
the outriggers to be installed.
16. A hoisting device according to claim 14 in which said base
assembly has a generally rectangular frame in plan view and four of
said slide sockets extend inwardly in generally diagonal directions
from the corners of the frame.
17. A hoisting device according to claim 16 in which a pair of
slide sockets are located at one end of said frame and extend in
opposite lateral directions whereby said one end can be placed
against a wall or obstruction with outriggers at the end fitted in
said pair of sockets rather than in the diagonal sockets at that
end.
18. A hoisting device according to claim 14 in which said base
assembly has a generally rectangular frame in plan view and in
which said hoist assembly comprises,
three multi-stage fluid-operated cylinders which rest, two on
adjoining corners of the frame and the third at the center of the
side of the frame opposite from said adjoining corners, and in
which said work platform is also generally rectangular and has
approximately the same horizontal extent and orientation as said
frame.
19. A hoisting device according to claim 18 in which said work
platform has corner posts slidably mounted to project downwardly
and be outwardly of said hoist assembly when in a storage position
and to project upwardly when in an operating position, and guard
rails mounted on the corner posts.
20. A portable hoisting device comprising,
a carriage,
a hoist assembly mounted on the carriage,
a work platform carried by the hoist assembly to be selectively
raised and lowered thereby between retracted and extended
positions,
a ladder supported by the carriage and extending to the work
platform when the hoist assembly is in retracted position,
handle grips near the top of the ladder,
a pair of ground support wheels adjacent the foot of the ladder
whereby the hoisting device can be handled like a hand truck by use
of said wheels and handle grips, said carriage having a pair of
horizontal slide sockets diverging on opposite sides of said ladder
outwardly of said pair of wheels and having a pair of horizontal
slide sockets at the opposite end of the carriage from the
ladder,
and four outriggers adapted to be slidably plugged into said pairs
of sockets and provide the ground support for the carriage.
21. A hoisting device according to claim 20 in which said carriage
has a pair of jacks located between said pairs of slide
sockets.
22. A hoisting device according to claim 20 in which said
outriggers each comprise an elongated tube fitting by one of its
ends into a respective said socket and having its opposite end open
to form a socket for selectively receiving a leveling jack
assembly.
23. A portable hoisting device comprising,
a base assembly presenting a plurality of horizontally opening
slide sockets spaced about its periphery,
a hoist assembly mounted in the base assembly,
a work platform carried by the hoist assembly to be raised and
lowered thereby,
and a plurality of outriggers adapted to be plugged into said
sockets, said base assembly having a generally rectangular frame in
plan view with one end of said frame having a pair of oppositely
extending lateral slide sockets for outriggers and the four corners
of the frame having diagonally extending slide sockets for
outriggers, said hoist assembly comprising three multi-stage
fluid-operated cylinders which rest, two on adjoining corners of
the frame opposite from said adjoining corners, and said work
platform also being generally rectangular and having approximately
the same horizontal extent and orientation as said frame.
24. A lift device comprising a base support, upwardly extending
hoisting means on the base support, a work platform mounted on the
hoisting means to be raised and lowered thereby, a guard rail
assembly on the platform including a plurality of interconnected,
spaced posts vertically slidable relative to the platform between
the raised, guarding position in which a major longitudinal portion
of each post projects above the platform and a storage position in
which a major longitudinal portion of each post is suspended below
the platform, intermediate guard rails slidably mounted on the
posts, flexible means extending from the top of the posts to said
intermediate rails whereby the latter are held at a predetermined
height relative to the posts when the posts are in raised, guarding
position and rest on the work platform when the posts are in
lowered, storage position, and locking means for selectively
holding the posts in said guarding position.
Description
This invention relates to lightweight portable multistage
telescopic lifts, particularly the type powered by a compressible
fluid such as carbon dioxide or air, and aims as an overall object
to provide an improved such lift whereby a worker can be hoisted
under stable safe conditions at greater heights than heretofore
considered feasible with such a device.
With respect to portability, the invention aims to provide a lift
which has a base of unusually small horizontal extent when the lift
is in collapsed storage position. In this regard the invention
further aims to provide an improved outrigger system which will
lend substantial stability when the lift is extended, has provision
for easy adjustment to contend with uneven floor conditions, will
permit the lift to be used close to walls or obstructions, can be
stowed with the rest of the lift in a compact manner, and can be
readily placed into either operating or storage position.
Concerning safety, an important object is to provide a safe working
platform with a guard rail assembly which can be easily transferred
when desired from a guarding position into an unusually compact
storage position.
Another object is to provide an arrangement by which the lift, when
in storage position, can be easily wheeled about and handled in the
manner of a hand truck.
Still a further object is to provide such a lift in which the
telescopic cylinders are of unsually inexpensive lightweight
construction and yet do not bind even though operated by a
compressible fluid.
For carrying out the above objects the invention provides an
improved bracing system whereby a group of parallel columns of
thin-walled aluminum telescoping cylinder can be cross-connected to
operate in unison for lifting a working platform.
In carrying out the aforesaid objects the present invention
comprises a novel base assembly, hoist assembly and work platform
assembly. The base assembly includes a carriage unit into which
outriggers are conveniently plugged in diagonal directions at the
rear and in optional diagonal or lateral directions at the front.
Jacks for levelling are provided which plug into the outriggers.
The carriage unit together with a ladder having handles at the top
and arranged for access to the work platform when the lift is
retracted, make it convenient to move the lift in the manner of a
hand truck. The hoist assembly includes three multi-stage cylinder
units on the base assembly which are braced in a novel manner to
move in unison without binding. A guard rail assembly for the work
platform is arranged to contract from guarding position to a
compact storage position in which supporting posts drop alongside
the hoist assembly and guard rails rest on the work platform.
The compactness, versatility and light weight of the lift unit of
this invention are attested to by the fact that embodiments thereof
have been constructed and used which have a platform height of 36
feet when extended, and yet are only 30 inches wide and 28-1/2
inches long when in retracted storage position with the outriggers
stowed and can be handled by only one man.
In the accompanying drawings:
FIG. 1 is a perspective view of a lift made in accordance with this
invention and with its hoist assembly shown extended to full
operating height and its outriggers in normal position;
FIG. 2 is a perspective view of the lift with the hoist assembly
retracted and as viewed from the rear left corner;
FIG. 3 is a perspective view of the carriage assembly of the lift
with the front outriggers illustrated in an alternate position for
working against a wall, and showing the manner of use of additional
stabilizing braces to the outriggers; and
FIG. 4 is a detail perspective view of the bracing for the hoist
cylinders.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring to the drawings, it is seen that in general the lift of
the present invention comprises a base assembly 10, a multi-stage
telescopic hoist assembly 11, and a work platform assembly 12. The
base assembly comprises a rectangular carriage 13 defined by a pair
of side rails 14-15 and front and rear rails 16-17 which are welded
at the corners to tubular diagonal members forming a pair of front
diagonal sockets 18-19 and a pair of rear diagonal sockets 20-21.
At its forward end the carriage also has a front tubular member
providing left and right sockets 21, 22 by its open ends. Near
their mouths the sockets 18-22 each have a respective set screw or
spring-loaded locking pin 23.
At the rear the carriage has a pair of struts 24 projecting
rearwardly from weld connections at the underside of the rear
diagonal sockets 20-21 and the rear rail 17. An axle 25 is
journaled in these struts and receives a pair of rear wheels 26-26'
which are complemented at the front corners of the carriage by a
pair of swivel casters 27-27'.
Four tubular outriggers 28-31 are provided, each having a swivel
caster 32 near one end and a detent (not shown) at the top near the
outer end for receiving a locking pin 23. The caster ends of the
outriggers are open to serve as sockets to selectively receive the
arm extension 34 of one or more levelling jacks 35 while the other
ends are adapted to plug into selected of the various sockets 18-22
as shown in the drawings. The casters 32 track at a level lower
than that of the casters 27-27' and wheels 26-26' when the
outriggers are in use. In other words, when the outriggers are
plugged into the carriage sockets the carriage casters and wheels
are lifted out of ground contact.
Accordingly, for ease of installation of the outriggers the side
rails 14-15 are provided with jack screws 35-35'. When, for
example, it is desired to first insert the outriggers 28 and 30 in
the left side of the carriage, the jack screw 35 is turned such as
to raise the wheel 26 and caster 27 sufficiently above the ground
to permit the outrigger 32 to be inserted into the left rear
diagonal socket 20 and the outrigger 28 to be plugged into the left
front diagonal socket 18 or the left socket 22. During that
operation, the right wheel 26' and caster 27' remain in ground
contact. Then jack 35 is raised to lower the casters on the left
outriggers 28, 32 into ground engagement and the wheel 26' and
caster 27' are raised by the jack 35'. This jack and the casters on
the left outriggers then support the carriage while the right
outriggers 29, 31 are being inserted in right rear diagonal socket
21 and in right front diagonal socket 19 or the right socket 22'.
Then jack 35' is screwed up so that the casters on the outriggers
29 and 31 also engage the ground. At that point the four outriggers
completely support the unit. The front sockets 22, 22' are used for
the front outringgers 28-29 when it is desired to move the carriage
closer to a wall than permitted when the front outriggers extend
diagonally from the sockets 18-19. It is preferred that the casters
27 and 32 be provided with side brakes.
Continuing to the hoist assembly 11, such preferably comprises
three or more multi-stage fluid-operated telescopic cylinder units
40 which are interconnected to move in unison. For purposes of
example three cylinder units 40 have been illustrated which are
arranged as the vertices of an equilateral triangle having two of
its apexes at the rear corners of the carriage 13 and the third
adjoining the center of the front rail 16. The cylinder units are
identical and are fixed to respective pads 41 secured on the base
assembly.
Respective two-piece upper and lower flanged clamping collars 42-43
are mounted on the ends of the bottom cylinders 40a of the cylinder
units 40. These collars are interconnected by three top braces 44
and three bottom braces 45 welded to the collar halves, and these
braces are reinforced by three pairs of crossed struts 46. These
struts are bolted or riveted in position after the three cylinders
40a have been carefully preset in parallel relation. By this
arrangement the cylinders 40a, collars 42-43, braces 44-45, and
struts 46 form a rigid precision base unit for the hoist assembly
11.
The respective three telescopic cylinders in each stage of the
hoist assembly 11 above the bottom stage are interconnected to move
in unison by three sets of two-piece horizontal braces extending
from respective halves of two-piece collars clamped around the
necked top portion of the cylinders. As shown in FIG. 4 each such
set comprises overlapping arms 50-51 of flat bar stock extending
from weld connections to half-collars 52-53, respectively, each
having flange extensions 54 formed with pairs of holes to receive
clamping bolts 55. Preferably the portions of the brace components
50 - 51 are drilled to provide registering holes for bolts or
rivets 56 after the hoist assembly 11 has been mounted on the
carriage 13, the three bottom stages 40a have been cross-braced,
and the half-collars 52-53 have been clamped in position.
substantially perfect cylinder alignment is achieved without
introducing warping stresses during the assembly operation. This is
very important in the preventing of binding of the cylinders,
particularly when thin-walled drawn aluminum tubing is used for
forming the cylinders. Such tubing helps make possible an
economical light-weight structure.
The work platform assembly 12 comprises a dielectric platform in
the form of a glass-reinforced plastic pan 60 and a guard rail
assembly adapted to drop into a lowered storage position relative
to the platform. The pan 60 is secured to the top of the uppermost
cylinders and also rests on the uppermost of the bracing arms
50-51. As shown in FIG. 2 the guard rail assembly has four corner
posts 61 slidably mounted in corner guides 62 projected through the
pan 60. The posts 61 are horizontally pierced a relatively short
distance above their lower ends to provide holes to receive
removable keeper pins 63 which bear as stops against the floor of
the pan to keep the posts in raised guarding position.
An upper set of four guard rails 64 interconnects the top of the
corner posts and a second set comprising three intermediate guard
rails 65 is slidably mounted by end collars 66 on the corner posts.
These intermediate rails are located at the front and two sides of
the unit and are prevented from dropping below the desired
intermediate level relative to the top rails 64, when the guard
rail assembly is in raised position, by chains 67 hanging from the
upper corners. The rear side of the platform is guarded at the
intermediate level by a chain 68 which has a releasable hook at one
end.
The storage position of the guard rail assembly 12 is shown in
phantom lines in FIG. 2. When the keeper pins 63 are removed the
corner posts 61 are free to slide downwardly through the corner
guides 62 on the outer sides of the hoist assembly 11. First, the
intermediate rails 65 engage the pan 60 and then as the posts
continue to drop the chains 67 slacken. Finally, the upper rails 64
drop onto the intermediate rails within the side walls of the pan
and stop further downward movement.
For ease of access to the work platform when it is in its lowered
position shown in FIG. 2, a ladder 70 is provided having top
handles 71. The two side racks 72 of the ladder are connected at
the bottom to a pair of mounting brackets 73 extending upwardly
from the free ends of the struts 24, and are connected toward the
top to a pair of brackets 74 projecting rearwardly from the
adjoining brace 44. As shown by the phantom position of outrigger
28 in FIG. 2, the outriggers 28-31 may be conveniently stowed
hanging by their caster ends from the work platform 60. With the
outriggers removed from their sockets and the guard rail 12 lowered
to its storage position, and entire lift unit can be tilted back
and conveniently manually wheeled about like a hand truck on the
rear wheels 26-26' while gripping the handles 71. The ladder rails
72 also act as glides which are useful, for example, in sliding the
unit over the edge of a truck bed on which it was being transported
to a work site.
For particularly high models of the lift, stabilizing braces 80 are
provided which extend from the outer ends of the outriggers
upwardly to the collars 42 at the top of the base unit of the hoist
assembly 11. These braces have a swivel 81 at the bottom and may be
locked in place by ball keeper pins 82 passing through registering
clevises and ears on the braces, the collars 42 and the
outriggers.
It is preferred that the hoist assembly be operated by a
compressible fluid be such that a lower group of the cylinders can
be charged, when extended, to a pressure higher than that required
to lift the load. In this manner the telescopic tower is made more
rigid when operated near its upper extent than would otherwise be
the case. This can be accomplished, for example, by charging and
dumping a lower group of the cylinders in each assembly through the
bottom cylinders and the remaining top groups of cylinders through
the top cylinders of the assembly, while keeping the two groups
internally isolated from one another. As a further example, such
can also be accomplished in the manner disclosed in the aforesaid
copending application, Ser. No. 889,235.
It is preferred to fabricate substantially all of the structural
parts of the lift as well as the hoist cylinders from aluminum in
order to make it feasible for one man to handle the unit. The
illustrated embodiment is particularly well adapted for aluminum
fabrication.
* * * * *