U.S. patent application number 11/670742 was filed with the patent office on 2008-08-07 for smooth transition dock leveler lip.
This patent application is currently assigned to Rite-Hite Holding Corporation. Invention is credited to Jonathan Andersen, Eric Bublitz, Norbert Hahn, Dave Holm, Matthew C. McNeill, Timothy Muhl, Kyle E. Nelson, Bradley J. Stone, Matt Sveum.
Application Number | 20080184503 11/670742 |
Document ID | / |
Family ID | 39402560 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080184503 |
Kind Code |
A1 |
Andersen; Jonathan ; et
al. |
August 7, 2008 |
SMOOTH TRANSITION DOCK LEVELER LIP
Abstract
A dock leveler includes a vehicle-engaging pivotal lip extending
from the front end of a pivotal deck, wherein the lip has one or
more unique features that provide a smooth transition for forklifts
traveling between the lip and a trailer bed upon which the lip is
resting. The smooth transition minimizes jolting and vibration of
the forklift and its driver as the forklift wheels pass over the
leading edge of the lip. The special features of the lip may
include one or more of the following: a curved traffic-bearing
surface terminating at a sharp or blunt leading edge, a
traffic-bearing surface that includes both flat and curved
sections, a multifaceted traffic-bearing surface that approximates
a curved surface, a rubber or plastic shock absorbing element, an
articulated nose piece at the lip's leading edge, and a main lip
plate that is coplanar with the deck's traffic surface (i.e., zero
crown angle).
Inventors: |
Andersen; Jonathan;
(Grafton, WI) ; Bublitz; Eric; (Milwaukee, WI)
; Hahn; Norbert; (Franklin, WI) ; Holm; Dave;
(Kewaskum, WI) ; McNeill; Matthew C.; (White Fish
Bay, WI) ; Muhl; Timothy; (Slinger, WI) ;
Nelson; Kyle E.; (Cedarburg, WI) ; Stone; Bradley
J.; (Port Washington, WI) ; Sveum; Matt;
(Wauwatosa, WI) |
Correspondence
Address: |
HANLEY, FLIGHT & ZIMMERMAN, LLC
150 S. WACKER DRIVE, SUITE 2100
CHICAGO
IL
60606
US
|
Assignee: |
Rite-Hite Holding
Corporation
Milwaukee
WI
|
Family ID: |
39402560 |
Appl. No.: |
11/670742 |
Filed: |
February 2, 2007 |
Current U.S.
Class: |
14/71.3 |
Current CPC
Class: |
B65G 69/2841 20130101;
B65G 69/2823 20130101; B65G 69/287 20130101 |
Class at
Publication: |
14/71.3 |
International
Class: |
E01D 1/00 20060101
E01D001/00 |
Claims
1. A dock leveler, comprising: a deck that includes a front edge
and a rear edge, the deck is pivotal about the rear edge to
selectively raise and lower the front edge; and a lip that includes
a leading edge, a hinged edge and a traffic-bearing surface
extending therebetween, the hinged edge is pivotally coupled to the
front edge of the deck such that the leading edge can selectively
rise and descend relative to the front edge of the deck, the
traffic-bearing surface includes a first approach surface, a second
approach surface and a final approach surface such that: a) the
first approach surface is adjacent to the leading edge of the lip;
b) the first approach surface is between the leading edge of the
lip and the second approach surface; and c) the final approach
surface is adjacent to the hinged edge of the lip, and the final
approach surface is between the second approach surface and the
hinged edge, wherein each of the first approach surface, the second
approach surface and the final approach surface are at an incline
relative to each other.
2. The dock leveler of claim 1, wherein each of the first approach
surface, the second approach surface and the final approach surface
are substantially flat.
3. The dock leveler of claim 1, wherein at least one of the first
approach surface and the second approach surface is curved.
4. The dock leveler of claim 1, wherein a curved surface exists
between the first approach surface and the second approach
surface.
5. The dock leveler of claim 1, wherein a curved surface exists
between the second approach surface and the final approach
surface.
6. The dock leveler of claim 1, wherein the leading edge provides a
generally flat surface that lies at an angle greater than zero
degrees relative to the first approach surface.
7. The dock leveler of claim 1, wherein the leading edge is a
substantially sharp line.
8. The dock leveler of claim 1, wherein the traffic-bearing surface
includes a polymeric element carried by the lip.
9. The dock leveler of claim 8, wherein the polymeric element
includes the leading edge of the lip.
10. The dock leveler of claim 8, wherein the polymeric element is
between the leading edge and the final approach surface.
11. The dock leveler of claim 8, wherein the polymeric element
includes a curved surface.
12. A dock leveler comprising: a deck that includes a front edge
and a rear edge, the deck is pivotal about the rear edge to
selectively raise and lower the front edge; and a lip that includes
a leading edge, a hinged edge and a traffic-bearing surface
extending therebetween, the hinged edge is pivotally coupled to the
front edge of the deck such that the leading edge can move
vertically relative to the front edge of the deck, the
traffic-bearing surface includes a curved surface.
13. The dock leveler of claim 12, wherein the leading edge provides
a generally flat surface that lies at an angle greater than zero
degrees relative to the curved surface.
14. The dock leveler of claim 12, wherein the leading edge is a
substantially sharp line.
15. The dock leveler of claim 12, wherein the traffic-bearing
surface includes a polymeric element carried by the lip.
16. The dock leveler of claim 15, wherein the polymeric element
extends to the leading edge of the lip.
17. A dock leveler comprising: a deck that includes a front edge
and a rear edge, the deck is pivotal about the rear edge to
selectively raise and lower the front edge; and a lip assembly
comprising a main piece and a leading edge piece, the main piece is
pivotally coupled to the front edge of the deck, the leading edge
piece is defectively coupled to the main piece.
18. The dock leveler of claim 17, wherein the main piece is between
the leading edge piece and the front edge of the deck.
19. The dock leveler of claim 17, wherein the leading edge piece
includes a leading edge that is generally a sharp straight line,
the leading edge is a portion of the leading edge piece that is
farthest away from the main piece of the lip assembly.
20. The dock leveler of claim 17, further comprising a first hinge
at the rear edge of the deck, a second hinge at the front edge of
the deck, and a third hinge between the leading edge piece and the
main piece of the lip assembly.
21. The dock leveler of claim 17, wherein the leading edge piece
extends substantially a full length along the front edge.
22. The dock leveler of claim 17, wherein the lip assembly includes
a plurality of leading edge pieces that are distributed along the
main piece.
23. The dock leveler of claim 17, wherein the leading edge piece is
at least partially comprised of a polymeric material.
24. The dock leveler of claim 17, wherein the leading edge piece
includes a curved surface.
25. The dock leveler of claim 17, further comprising an adhesive
that bonds the leading edge piece to the main piece.
26. The dock leveler of claim 17, further comprising a fastener
that holds the leading edge piece in place.
27. The dock leveler of claim 17, wherein the leading edge piece
includes an interlocking feature that helps hold the leading edge
piece in place.
28. The dock leveler of claim 17, wherein the main piece has a main
traffic surface, the deck has a deck traffic surface, and the main
piece can pivot to a position where the main traffic surface and
the deck traffic surface are substantially coplanar.
29. A dock leveler comprising: a deck that includes a front edge
and a rear edge, the deck is pivotal about the rear edge to
selectively raise and lower the front edge; a lip that includes a
leading edge, a hinged portion and a traffic-bearing surface
extending therebetween, the hinged portion is pivotally coupled to
the front edge of the deck such that the leading edge can move
vertically relative to the front edge of the deck; and a polymeric
piece that provides a least a portion of the traffic bearing
surface.
30. A dock leveler comprising: a deck that includes a front edge
and a rear edge, the deck is pivotal about the rear edge to
selectively raise and lower the front edge; and a lip assembly
comprising a main piece and a leading edge piece, the main piece is
pivotally coupled to the front edge of the deck, the leading edge
piece is pivotally coupled to the main piece such that the main
piece is between the leading edge piece and the front edge of the
deck.
Description
FIELD OF THE DISCLOSURE
[0001] The subject disclosure generally pertains to dock levelers
and more specifically to a transitional lip extending from the deck
of a dock leveler.
BACKGROUND OF RELATED ART
[0002] A typical loading dock of a building includes an exterior
doorway with an elevated platform for loading and unloading
vehicles such as trucks and trailers. Many loading docks have a
dock leveler to compensate for a height difference that may exist
between the loading dock platform and an adjacent bed of a truck or
trailer. A dock leveler usually includes a deck that is hinged
along its back edge so that the deck can pivotally adjust the
height of its front edge to an elevation that generally matches the
height of the rear edge of the truck or trailer bed.
[0003] In addition, usually a front hinge pivotally connects an
extension plate or lip to the front edge of the deck. The front
hinge allows the lip to pivot between a stored, pendant position
and an extended, operative position. In the extended position, the
lip can rest upon the trailer bed to form a bridge between the deck
and the bed. This allows personnel and material handling equipment,
such as a forklift truck, to readily move on and off the trailer
during loading and unloading operations.
[0004] Often, the leading edge of the lip that rests upon the
trailer bed is beveled to create a miniature ramp that minimizes
physical shock to material handling equipment as their wheels
travel over that leading edge. Nonetheless, the lip's leading edge
and the rest of the lip can still jar the moving equipment and its
driver. The magnitude of the jolt is a function of numerous factors
including, but not limited to, the lip's thickness, the geometry of
the lip's leading edge, the lip-to-deck crown angle (angle between
the upper surfaces of the lip and the deck), angle between the
upper surfaces of the lip and the trailer bed, height differential
between the trailer bed and the loading dock's elevated platform,
the hardness and diameter of the material handling equipment's
wheels, the material handling equipment's suspension, the speed of
the material handling equipment as it passes over the lip's leading
edge, the combined weight of the material handling equipment and
the load it is carrying, and the suspension of the trailer being
loaded or unloaded of its cargo.
[0005] Some of the shock occurring at the lip might be reduced by
providing a dock leveler with a crown angle that varies as a
function of the deck's angle of inclination. Such a dock leveler is
disclosed in US published patent application 2006/0150348A1.
Although varying the crown angle might reduce the mechanical shock
caused by the height differential between the truck bed and the
dock's elevated platform, there are still many other shock-causing
factors that could be addressed.
[0006] Consequently, a need exists for a better dock leveler that
provides a smooth transition between the dock leveler's lip and a
trailer bed upon which the lip is resting. Preferably, the dock
leveler addresses a broad range of often uncontrollable factors
that can reduce the smooth traveling of material handling equipment
as the equipment travels between the dock leveler's lip and the
trailer bed.
SUMMARY
[0007] In some examples, a dock leveler lip includes a curved
leading edge to smoothen the transition between the lip and the top
surface of a trailer bed.
[0008] In some examples, a dock leveler lip includes a shock
absorbing polymeric element that minimizes mechanical shock and
vibration to material handling equipment traveling over the
lip.
[0009] In some examples, the shock absorbing polymeric element
includes an interlocking feature that helps hold the element in
place.
[0010] In some examples, a dock leveler includes an articulated
lip.
[0011] In some examples, a dock leveler lip includes a plurality of
flat, inclined surfaces that approximate a curved surface.
[0012] In some examples, a dock leveler lip includes a combination
of flat and curved surfaces.
[0013] In some examples, a dock leveler lip includes a curved
traffic-bearing surface so that the lip can terminate at a
generally sharp leading edge without the lip being too thin at that
area of the lip.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a side view of a vehicle backing toward a dock
leveler whose deck is at a stored, cross-traffic position.
[0015] FIG. 2 is a side view similar to FIG. 1 but showing the
vehicle having already backed into the dock with the dock leveler
moving into an operating position.
[0016] FIG. 3 is a side view similar to FIG. 2 but showing the dock
leveler lowering its deck upon the vehicle's trailer bed.
[0017] FIG. 4 is a side view similar to FIG. 3 but showing the dock
leveler in an operative position with a forklift traveling over the
lip of the dock leveler.
[0018] FIG. 5 is a side view similar to FIG. 4 but showing the dock
leveler engaging a higher trailer bed.
[0019] FIG. 6 is a side view similar to FIG. 4 but showing the dock
leveler engaging a lower trailer bed.
[0020] FIG. 7 is a side view a dock leveler lip according to one
embodiment.
[0021] FIG. 8 is a side view of a dock leveler lip according to a
second embodiment.
[0022] FIG. 9 is a side view of a dock leveler lip according to a
third embodiment.
[0023] FIG. 10 is a side view of a dock leveler lip according to a
fourth embodiment.
[0024] FIG. 11 is a side view of a dock leveler lip according to a
fifth embodiment.
[0025] FIG. 12 is a side view of a dock leveler lip according to a
sixth embodiment.
[0026] FIG. 13 is a partially exploded perspective view of the dock
leveler and lip of FIG. 12.
[0027] FIG. 14 is a side view of a dock leveler lip according to a
seventh embodiment.
[0028] FIG. 15 is a side view similar to FIG. 14 but showing the
lip engaging a higher trailer bed.
[0029] FIG. 16 is a side view similar to FIG. 14 but showing the
lip engaging a lower trailer bed.
[0030] FIG. 17 is a side view similar to FIG. 14 but showing an
alternate embodiment.
[0031] FIG. 18 is a side view similar to FIG. 11 but showing an
alternate embodiment.
DETAILED DESCRIPTION
[0032] FIGS. 1-6 show a loading dock 10 with a dock leveler 12 for
facilitating the loading and unloading of cargo on a trailer bed 14
or some other vehicle or truck bed. Dock leveler 12 includes a deck
16 that due to a rear hinge 18 can pivot about a rear edge 20 to
adjust the height of its front edge 22 so that trailer bed 14 and
the deck's front edge 22 can be at about the same height. Deck 16
can pivot over a range of positions including, but not limited to,
a raised position (FIG. 2), a cross-traffic position (FIG. 1), and
a below-dock position (FIG. 6).
[0033] To bridge the gap between the deck's front edge 22 and the
rear edge of trailer bed 14, a front hinge 24 pivotally couples a
lip 26 to the deck's front edge 22. Lip 26 can pivot between an
extended position (FIG. 3) and a pendant position (FIG. 1).
Together, deck 16 and lip 26 provide a bridge over which a forklift
28 and other material handling equipment can travel between trailer
bed 14 and an elevated platform 30 of dock 10.
[0034] As the forklift's wheels roll between trailer bed 14 and lip
26, forklift 28 and its driver may experience some jolting and
vibration because the upper surface of trailer bed 14 and a
traffic-bearing surface 32 of lip 26 are not perfectly coplanar. To
minimize this vibration, a leading edge 34 of lip 26 includes one
or more novel features that provide a smooth transition between
trailer bed 14 and deck 16. These features have been designed while
carefully considering the typical operation of a dock leveler.
[0035] In operation, trailer bed 14 is backed into the loading
dock, as shown in FIG. 1. At this point, deck 16 is at its stored,
cross-traffic position where a driveway surface 36 of deck 16 is
generally flush with platform 30, and lip 26 is at its pendant
position. In some cases, edge 34 of lip 26 rests upon a set of lip
keepers 38 so that lip 26 can help support the weight of the deck
at its cross-traffic position. In cases where the dock leveler does
not include lip keepers, a pedestal installed underneath the deck
can be used for supporting the deck's weight. An example of such a
pedestal is disclosed in U.S. Pat. No. 3,530,488.
[0036] Next, referring to FIG. 2, deck 16 rises and lip 26 swings
out to extend edge 34 of lip 26 out over the top of trailer bed 14.
Then, in FIG. 3, deck 16 descends to place the extended lip 26 upon
trailer bed 14. The movement of lip 26 and deck 16 can be carried
out in any of a wide variety of ways that are well known to those
of ordinary skill in the art. The movement, for example, can be
powered, manually driven, or a combination of the two. Mechanisms
for moving deck 16 or lip 26 include, but are not limited to,
hydraulic cylinder or bladder, pneumatic cylinder or bladder,
mechanical linkage, drive screw, rack and pinion, winch, mechanical
spring, gas spring, and various combinations thereof.
[0037] Once lip 26 is resting upon trailer bed 14, as shown in FIG.
4, forklift 28 can readily travel between platform 30 and trailer
bed 14. The actual inclination of deck 16 and the angle between the
upper surfaces of bed 14 and lip 26 is partially determined based
on the relative heights of bed 14 and platform 30. FIG. 4, for
instance, shows the deck's inclination when dock leveler 12 engages
a trailer bed of moderate height, FIG. 5 shows dock leveler 12
engaging a relatively high trailer bed 14a, and FIG. 6 shows a
relatively low trailer bed 14b. Leading edge 34 being able to lie
directly against trailer bed 14a even though bed 14a is higher than
platform 30 is because the upper traffic-bearing surfaces of lip 26
and deck 16 are at a slightly positive crown angle 40 (about
5-degrees).
[0038] Although crown angle 40 ensures that the lip's leading edge
34 is resting directly upon trailer bed 14, the transition between
edge 34 and bed 14 can still cause some vibration and jolting of
forklift 28 and its driver. To minimize this vibration, a lip 26a
can be provided with a smoothly curved or contoured traffic-bearing
surface 42, as shown in FIG. 7. In this example, lip 26a has a
leading edge 34a that is a substantially sharp line, which helps
minimize any impact as a forklift wheel rolls from trailer bed 14
onto lip 26a. Traffic-bearing surface 42, which lies between
leading edge 34a and a hinged edge 44, comprises a first approach
surface 46, a second approach surface 48, and a final approach
surface 50.
[0039] Due to the continuous curvature of the leading portion of
bearing-surface 42, first approach surface 46 and second approach
surface 48 are at an incline relative to each other. A tangent line
52 to first approach surface 46, for instance, lies at an angle
(not parallel) to a line 54 that lies tangent to second approach
surface 48, yet the two surfaces 46 and 48 smoothly blend due to a
curved surface 56 between surfaces 46 and 48. In some cases,
surfaces 46, 48 and 56 have the same radius and center of
curvature.
[0040] In an alternate example, shown in FIG. 8, a lip 26b includes
a more blunt leading edge 34b that might be more durable than a
sharp edge. Leading edge 34b is a generally flat surface that lies
at an angle (greater than zero degrees) relative to the lip's first
approach surface 58. In this example, lip 26b has a traffic-bearing
surface 60 that extends between leading edge 34b and hinged edge
44. Traffic bearing surface 60 comprises first approach surface 58,
second approach surface 48, and final approach surface 50. Except
for the slight difference between leading edges 34a and 34b,
traffic bearing surfaces 42 and 60 are substantially the same.
[0041] Because a curved surface can be more difficult to machine
than a flat surface, FIG. 9 shows an alternate lip 26c that
includes a traffic-bearing surface 62 comprising a plurality of
flat surfaces, which approximate the curved surfaces of lips 26a
and 26b. Lip 26c includes a leading edge 34c similar to edge 34b
(or similar to edge 34a). Traffic-bearing surface 62 of lip 26c
extends from leading edge 34c to hinged edge 44. Surface 62
comprises a first approach surface 66, a second approach surface
68, and final approach surface 50. Each surface 66, 68 and 50 is
substantially flat and lies at an incline relative to the
others.
[0042] In another example, shown in FIG. 10, a lip 26d includes a
leading edge 34d similar to edge 34c (or similar to edge 34a). A
traffic-bearing surface 70 of lip 26d extends from leading edge 34d
to hinged edge 44. Traffic bearing surface 70 comprises a
substantially flat first approach surface 72, a curved second
approach surface 74, and substantially flat final approach surface
50. Second approach surface 74 provides a smooth tangential
transition between first approach surface 72 and final approach
surface 50.
[0043] To create a more shock absorbing lip and/or to achieve a
curved traffic-bearing surface without having to machine such a
surface, a lip 26e can comprise a metal plate 76 to which a formed
polymeric element 78 can be attached, as shown in FIG. 11. Element
78 can be attached in any suitable manner including, but not
limited to, an adhesive 80, a threaded fastener 82, a rivet, and/or
a mechanically interlocking feature (e.g., tongue-and-groove,
plug-and-hole, etc.). Element 78 can be of any desired shape. In
this particular example, element 78 is of a shape that provides a
traffic-bearing surface 84 that is similar to surface 60 of FIG. 8.
Element 78 can also be of any desired material, including but not
limited to, neoprene rubber or polyurethane. Any suitable
manufacturing process including, but not limited to, extrusion,
plastic injection molding, and machining can produce element 78.
Element 78 can be one continuous piece that extends the full width
of deck 16, or element 78 can comprises a plurality of segments.
The phantom lines of FIG. 11 illustrate the flexure of element 78
as a strong lower edge 83 of lip 26e rests firmly upon trailer bed
14. In addition to flexibility, element 78 may advantageously have
shock or vibration absorption or dampening properties. Such
properties would serve to minimize or eliminate vibration
transmitted from the leveler to the forktruck operator resulting
from contact therebetween and/or movement of the forktruck over the
leveler, or at least the lip.
[0044] When a formed polymeric element or insert is used, the
leading edge of the lip might be more durable if the underlying
metal plate of the lip extends all the way to the tip of the lip.
FIGS. 12 and 13, for example, show a lip 26f comprising a formed
polymeric element 86 attached to a metal plate 88. Plate 88 extends
fully to a leading edge 34f of lip 26f so that the strength of edge
34f is sufficient to support the weight of deck 16 when lip 26f is
in its pendant position held by lip keepers 38 (FIG. 1). Element 86
can be comprised of a series of segments 90, which might make lip
26f easier to manufacture, ship and assemble. Moreover, worn
segments could be replaced with new ones or their positions could
be interchanged as some segments 90 in high traffic areas wear
faster than others. Although element 86 could be attached in any
suitable manner, such as those mentioned with reference to element
78 of FIG. 11, each segment 90 could include a plurality of plugs
92 that press-fit into a corresponding plurality of holes 94 in
plate 88.
[0045] In another embodiment, shown in FIGS. 14, 15 and 16, an
articulated lip assembly 26g comprises a metal or polymeric nose
piece 98 that is pivotally attached to a metal plate 100 (main
piece). A hinge 102 or pivotal connection between nose piece 98 and
plate 100 allows piece 98 to lie generally flat against trailer bed
14 regardless of whether the trailer bed's elevation is high as
shown in FIG. 15, low as shown in FIG. 16, or at an intermediate
elevation as shown in FIG. 14. FIGS. 14, 15 and 16 generally
correspond to FIGS. 4, 5 and 6 respectively. In this example, lip
26g includes a generally sharp leading edge 34g, and a
traffic-bearing surface 96 extends between leading edge 34g and
hinged edge 44. Although edge 34g is shown as a sharp edge, leading
edge 34g could by of any shape including, but not limited to the
shapes illustrated in FIGS. 7-13. Nose piece 98 can be one
continuous piece that extends most of the full width of deck 16, or
piece 98 can comprises two or more segments (plurality of leading
edge pieces) that are distributed along plate 100 in a manner
similar to the distribution of segments 90 of FIG. 13.
[0046] In some examples, as shown in FIG. 17, an articulated lip
assembly 26h comprises nose piece 98, an intermediate link 104, and
a main piece 106. The articulation of assembly 26h allows a leading
edge 108 of nose piece 98 to rest upon trailer bed 14 even when bed
14 is higher than deck 16. Unlike many other dock levelers, this
design does not require a crown angle where main piece 106 abuts
the front edge of deck 16 (see crown angle 110 of FIG. 4). Instead,
a main traffic surface 112 of main piece 106 is substantially
coplanar with deck traffic surface 36 of deck 16. This is a
significant advantage because crown angles can be difficult to
produce and maintain.
[0047] Alternatively, FIG. 18 shows a lip assembly 26k where the
articulated portion of assembly 26h of FIG. 17 is basically
replaced by a flexible leading edge piece 114 similar to element 78
of FIG. 11. When trailer bed 14 is higher than deck 16, as shown in
FIG. 18, a relatively stiff main piece 116 can rest solidly upon
bed 14, while a wheel 118 from a forklift or other type of material
handling equipment can deflect leading edge piece 114 down against
bed 14, thereby providing wheel 118 with a generally smooth path to
travel between bed 14 and deck 16. Again, this design does not
require a crown angle where main piece 116 abuts the front edge of
deck 16, thus a main traffic surface 120 of main piece 116 can be
substantially coplanar with deck traffic surface 36 of deck 16.
[0048] It should be noted that leading edge piece 114 (FIG. 18),
nose piece 98 (FIG. 17), and element 90 (FIG. 12) are all
deflectively coupled to a main piece. The term, "deflectively
coupled" refers to a connection between two pieces where some
localized or total relative movement can occur between the two.
Examples of such movement include, but are not limited to,
resilient bending, resilient deformation, resilient localized
compression, and pivotal movement.
[0049] Although the invention is described with respect to various
examples, modifications thereto will be apparent to those of
ordinary skill in the art. The scope of the invention, therefore,
is to be determined by reference to the following claims.
* * * * *