US3786530A - Dock leveler - Google Patents

Abstract

A swingable deck having a pivoted end lip, means for extending the lip, means for holding the lip extended, means for releasing the lip from its extended condition, and means for returning the deck to its initial position.

Description

United States Patent 1191 Le Clear [451 Jan. 22, 1974 1 1 DOCK LEVELER [75] Inventor: Robert L. Le Clear, Albion, Mich.

[73] Assignee: T & S Equipment Company, Albion,

Mich.

[22] Filed: June 24, 1971 [21] App1.No.: 156,396

[52] U.S. Cl. 14/71 51 1111. C1. ..B65g 11/00 [58] Field of Search 14/71 [56] References Cited UNITED STATES PATENTS 3,662,416 5 1972 Brooks... 14/71 3,323,158 6/1967 Loomis.....

3,316,575 5/1967 Larsen 14/71 3,137,017 6/1964 Pfleger 14/71 3,203,002 8/1965 McGuire..... 14/71 3,579,696 5/1971 Hecker 14/71 3,444,574 5/1969 Le Clear 14/71 3,475,778 11/1969 Merrick 14/71 3,500,486 3/1970 Le Clear 14/71 Primary ExaminerNile C. Byers, Jr. Attorney, Agent, or FirmBurton L. Lilling; James E. Siegel; Henry A. Marzullo, Jr.

[57] ABSTRACT A swingable deck having a pivoted end lip, means for extending the lip, means for holding the lip extended, means for releasing the lip from its extended condition, and means for returning the deck to its initial position.

16 Claims, 5 Drawing Figures PATENTED JAN 2 21974 SHEU 2 OF 4 INVENTOR DOCK LEVELER BACKGROUND OF THE INVENTION As is well known to those versed in the art, presently available dock boards or levelers attempt to incorporate therewith a pivoted end lip for overlying or resting on a truck bed and automatically accommodating to truck beds of different and varying heights.

Previously proposed pivoted dock board lips have not been entirely satisfactory, requiring relatively complex, expensive and easily damaged mechanisms, lacking versatility in use throughout a wide range of truck bed heights and other variable conditions, and being subject to damage upon impact by trucks.

SUMMARY OF THE INVENTION Accordingly, it is an important object of the present invention to provide a dock leveler or dock board of the type described, incorporating a pivoted lip, which overcomes the above mentioned difficulties, is relatively simple and sturdy in construction, durable and reliable in operation throughout a long useful life, relatively simple to manufacture and install, requiring a minimum of maintenance, being highly automatic in use, and well adapted to accommodate to truck beds of different heights and other varying conditions of use.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings, which form a material part of this disclosure.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, which will be exemplified in the construction hereinafter described, and of which the scope will be indicated by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end perspective view showing a dock leveler constructed in accordance with the teachings of the present invention, the deck being elevated to expose the operating structure there below.

FIG. 2 is a partial side elevational view showing the dock leveler of FIG. 1, from the left-hand side thereof, ina lowered position.

FIG. 3 is a partial side elevational view showing the lip extending mechanism of the dock leveler in the locked position and being taken from the right side of FIG. 1, and showing the deck in a loading position.

FIG. 4 is a side elevational view, showing the righthand side of the dock leveler of FIG. 1, but illustrating the leveler in an intermediate position of elevation, and

FIG. 5 is a fragmentary perspective view of the lip extending mechanism of FIG. 3 but shown from the left side of FIG. 1, and being locked by a cam.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to the drawings, and specifically to FIG. 1 thereof, a dock leveler or dock board is there generally designated 10, and includes a generally rectangular or otherwise suitably configured board or deck 11 mounted for swinging up and down movement relative to a fixed structure 12, which may be a loading dock, stationary building, or the like.

More specifically, the deck 11 is mounted at its inner end for swinging movement about a generally horizontal axis, as of horizontally aligned pivots 15. By this means, the deck 11 is swingable to displace its outer or front end 16 vertically as required to accommodate to the height of a truck bed. Carried by the outer or forward end 16 of swingable deck 11 is a lip 17. The lip may be of generally rectangular outline configuration, being coextensive with the outer deck end 16, and swingably connected to the deck, as by a generally horizontally extending pivotal connection 18. Thus, by the pivotal connection 18 the lip 17 is swingable between an upward and outward extending, or outstanding position shown in FIG. 1, and a depending or retracted position shown in FIG. 2.

Carried by the fixed structure 12, beneath the deck 11, may be an arm 20 pivotally mounted at one end, as by horizontal journal means 21 for swinging movement about the axis of journal means 21, generally parallel to the axis of pivots 15 mounting the deck. Suitable resilient means, such as a plurality of tension springs 22, may be connected between a fixed member or beam 23 and respective depending extensions 24 rigid with the arm 20 for rotation therewith about the axis of pin 21. By this spring means, the arm 20 is resiliently urged upwardly, and is provided on its outer end with a cam follower or roller 25 in rolling, bearing engagement with a specifically configured engagement member or cam 26 fixedly carried on the underside of deck 11. The arm 20, by its rolling engagement of follower 25 with cam 26, serves to substantially counterbalance the weight of deck 11 and mechanism thereof, to permit of easy upward swinging of the deck and facilitate location of the deck at any selected angle of elevation within a predetermined range above and below dock level.

Depending from the pivot connection 18, and specifically being rigid with a hinge knuckle 30 of the lip 17, and extending generally radially therefrom, is an arm 31, being swingable with the lip 17 through an opening 32 in the outer or front end wall 16 of the deck 11. Located in spaced relation between the lip arm 31 and inner or rear end pivot 15 of the deck 1 1, and mounted on the underside of the deck, is a laterally, generally horizontally extending journal shaft or pivot 33. A lip actuating arm 34 extends from the shaft 33 for rotation about the axis thereof, and suitable link means 35 extend between and has its opposite ends pivotally connected to the respective ends of arms 31 and the lip actuating arm 34. In particular, the link means 35 is a telescopically arranged two-part link, including inner and outer extensile and retractile link parts 36 and 37. That is, the link parts 36 and 37 are retractable to a limiting position for operation in compression when in the limiting contracted condition, and are freely extensible so as to be ineffective in tension.

A suitable lip counter balance tension spring 40 has one end fixed forwardly, as to a bracket 41 carried by the underside of deck 11, the other, rearward end of spring 40 being suitably connected by means of another arm 34' extending from the shaft 33 for rotation about the axis thereof so as to resiliently urge the latter and its radially extending arm 34' generally forwardly or outwardly, counterclockwise as seen from the right in FIG. I.

Also carried by shaft 33 for swinging movement about the axis thereof, and rigid or integral with arm 34', is an arm 42 carrying on its lower end a cam follower or roller 43. Fixedly mounted on the fixed structure l2 beneath the deck 11 is a cam 44 located and configured for operating engagement with the follower 43 of arm 42. As noted hereinabove, the other, upwardly extending end of arm 42 is connected to the rear end of the resilient tension member or counter balance spring 40, which has its forward end connected to the deck 11, as to a depending bracket 41.

It will now be appreciated that swinging movement of arm 34 upon raising and lowering of deck 11 is controlled by the action of cam 44 on arm 42, the latter being held in following engagement with the cam by resilient means 40. Cam 44 is configured so as to permit arm 34 to rotate counterclockwise (as seen from the right in FIG. 1) upon upward movement of deck 11 under the force of spring 40, to thereby extend or swing the lip 17 upward by the action of fully contracted link means 35 in compression. Downward movement of the deck 11 will permit downward swinging or retraction of lip 17, but does not positively effect such action, as the lip may be held outstanding and the link means 35 extended to elongate its telescopic parts 36 and 37.

An additional journal or shaft 45 is carried on the underside of deck 11, extending horizontally in substantial parallelism with pivot means and shaft 33. Extending between shaft 45 and the end of lip arm 31 is a suitable adjustable linkage 46, including a pair of links 47 and 48, best seen in FIG. 4. Although threaded rod means and a suitable turnbuckle type of construction is shown, other suitable elements, such as adjusting flat bars fastened together may also be employed.

The links 47 and 48 have their adjacent ends pivotally connected together, as by pivot means 49, and have their opposite or distal ends respectively connected to shaft 45 and the end of lip arm 31. In the condition shown in FIG. 4, the links 47 and 48 are swung slightly past dead center, the connecting pivot 49 being slightly below a line extending between the distal end pivots of the links. A bracket 50 is fixed to one of the links, say link 47, and carries a stop member 51, which may be a threadedly adjustable element or bolt, for abutting engagement with the link 48. This stop member 51 thereby limits relative swinging of the links 47 and 48 to the just past dead-center position shown in FIG. 4, and thereby effectively retains or locks the lip 17 in its illustrated outstanding position.

As thus far described, it will be apparent that the deck 11 may be swung upwardly and downwardly while the linkage 46 effectively holds the lip 17 in its outstanding position and thereby defines a lip holding mechanism.

However, one of the links 47 and 48, say the latter, may carry a releasing abutment, say a leg 52, which may be pivoted, as by a pivotal connection 53, to the link 48 at a location adjacent to the pivot 49. If desired, the leg 52 may fall gravitationally or require deliberate downward swinging about pin 53, as conditions dictate. In either event, downward swinging movement of the deck 11, with the lip 17 positively held in its outstanding position, will move the linkage 46 and its abutment 52 into abutting engagement with a fixed nether member, such as block 54, which effects relative upward displacement of the links 47 and 48 through dead center to permit release and free downward falling movement of the lip 17. This position of lip release upon downward deck movement may be selectively determined, as by the height of a suitable stop or engagement member 54, the length of leg 52, or other selected dimension. Although spring 58, connected at one end to the distal end of a fixed point(arm 57') extending from and forming part of an element 55 secured to the deck 11, and at its front end to an arm 59 rigidly secured to the shaft 45, counter balances the lip 17 to a certain extent; it primarily assists and insures that links 47 and 48 will lock'across center and not bounce unlocked during operation of the dock leveler.

As best shown in FIGS. 3 and 5, the lip trip mechanism comprises an over center locking device which is released at a predetermined level by means of a suitable lost motion device, such as chain 80. Extending from the arm 34 and fixedly mounted thereto, is an arm 82 which is connected by means of a spring 83 to a pivotable lever arm 84 pivotal about a shaft 86. The chain being connected to the lower end of the lever arm 84 and the frame of the leveler at 85. Another element 88 is pivotably mounted to the lower end of arm 34 at shaft axis and connects at the front end to the lever arm 84 at shaft 86 and at the rear end to a connecting pivot 92. A further link 94 extending from pivot 92 is connected at point 96 to a leg 98 fixedly secured to the deck 11. Bracket 91 fixed suitably to link 94 carries stop member 93, similar to member 51, for abutting engagement with link 88 so as to limit swinging of the links just past dead center position, as shown in FIG. 3.

While the hereinbefore described action of lip extending mechanism 35, 34, 45 is effective upon upward swinging movement of deck 11, it relies upon the force of spring 40, and is thereby not positive in action. At some upper position of deck movement, a positive lip extending action is desirable, and toward this end, see FIG. 2, the lip 17 is provided on another hinge knuckle with an arm 66. A generally horizontal, laterally extending shaft 61 is carried by the deck 11,just rearward of the arm 60, and a lever 62 is mounted for swinging movement about the axis of shaft 61. A link 63 has one end, its rearward end, pivotally connected, as by pivot pin 64 to the upper end of lever 62 above shaft 61, and the other, forward link end is connected, as by a pivot 65 to the end of arm 60. A suitable cam follower or roller 66 may be provided on the other, lower end of lever 62, and a lip extension assist element or crank arm 67 may extend transversely from an intermediate region of the lever 62, adjacent to the shaft 61. By actuating means, such as a tension member or chain 68, being connected at its opposite ends to the fixed substructure l2 and outer end of arm 67, upward swinging movement of deck 11 at a predetermined upper position positively effects outward swinging or extension of lip 17. Also, there is provided on the fixed substructure 12, a return to level ramp or cam 69 for operating engagement with the follower 66 to control swinging of lip 17 when the deck is in a lowered position. Thus, unless there is a load on the deck, when a truck (not shown) pulls away the lip 17 drops and link 63 pushes link 64 resulting in the roller follower 66 going up the cam 69 which returns the deck to a positive locked, level posit1on.

Optionally, the deck 11 may be provided at its forward or outer end with a pair of laterally spaced depending members or safety legs 70 freely swingable, as by pivotal connections 71, for positive supporting engagement of the deck in a level or slightly below level position. Also, in this regard, the lip 17 rests in a suitable pair of cross trafr'ic supports 19 when the deck is returned to a level and cross traffic position. However, the safety legs 70 may be rendered ineffectual, as by suitable actuating means, such as a chain '72, being connected to chain 57, and swingable upwardly to remove the legs from their depending relation. It is the function of such safety legs 70 to prevent the deck from bottoming out in the event a truck inadvertently pulls out when, for example, a fork truck is on the deck 111. Thus, the deck 11 will not drop all the way down but will be retained in position and accordingly the fork truck would not roll downwardly into the truck approach. Thus, when servicing a truck with a bed with a height higher than the dock, legs 7t) and link 52 are left in their vertical position. However, when servicing a truck with a height lower than the dock, both legs 70 and link 52 must be retracted. Should link 52 not be retracted, the lip 17 would trip as soon as it came in contact with engagement member or stop 5&. When link 52 is retracted, the deck 11 may therefore travel down a further predetermined distance before the lip 17 is tripped.

From the foregoing, it is seen that the present invention provides a dock leveler or dock board which is extremely simple in construction, for long lasting durability and reliability in use, and which otherwise fully accomplishes its intended objects.

Although the present invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be made within the spirit of the invention.

What is claimed is:

l. A dock leveler comprising a fixed structure, a deck having one end pivoted to said structure for swinging up and down movement of its other end, a lip pivoted to said other deck end for movement with said deck and swinging movement relative thereto between outstanding and depending positions, a holding mechanism connected to said lip and deck to hold said lip in its outstanding position and release said lip to its depending position, lip extending means connected to said lip to move the latter to its outstanding position upon upward deck movement, said holding mechanism serving to hold said lip in its outstanding position upon said upward deck movement and downward return of said deck to a predetermined lower position, actuating means located for operative actuation of said holding mechanism to release said lip to its depending position upon said downward return of said deck to said predetermined lower position; said holding mechanism comprising a linkage swingable into and out oflimited overcenter position with said lip outstanding to positively retain the latter outstanding; said linkage comprising a pair of links having their adjacent ends pivotally connected together and having their distal ends respectively pivoted to said lip and deck, and stop means carried by one of said links and engageable with the other of said links to limit relative swinging movement to said over-center position; and said actuating means comprising an abutment located to displace said links out of their over-center position upon downward deck movement to said predetermined lower position.

2. A dock leveler according to claim 1, said lip extending means comprising a crank arm pivotally carried by said deck and operatively connected to said lip for swinging the latter upwardly upon pivotal movement of said crank arm, and operating means connected between said crank arm and structure to operate the lip extending means on upward swinging movement of said deck.

3. A dock leveler according to claim ll, said abutment comprising a leg depending from one of said links adjacent to said adjacent link ends for abutting engagement with the nether fixed structure to effect said displacement.

A. A dock leveler according to claim 1, said lip extending means comprising linkage means connected between said deck, fixed structure and lip to effect outstanding movement of the latter upon upward deck movement, said linkage means being resiliently biased to effect yieldable lip extension, and cam means operatively associated with said linkage means to hold the latter against said resilient biasing.

5. A dock leveler according to claim 4, said linkage means being freely telescopic in one direction to render said lip extending means ineffective to retract said lip.

6. A dock leveler according to claim ll, said lip extending means comprising linkage means connected between said deck, fixed structure and lip to effect positive outstanding movement of the latter upon upward deck movement to a predetermined upper position and positive retracing link movement upon downward deck movement to a predetermined lower position.

'7. A dock leveler comprising a fixed structure, a deck having one end pivoted to said structure for swinging up and down movement of its other end, a lip pivoted to said other deck end for movement with said deck and swinging movement relative thereto between outstanding and depending positions, a holding mechanism connected to said lip and deck to hold said lip in its outstanding position and release said lip to its depending position, lip extending means connected to said lip to move the latter to its outstanding position upon upward deck movement, said holding mechanism serving to hold said lip in its outstanding position upon said upward deck movement and downward return of said deck to a predetermined lower position, actuating means located for operative actuation of said holding mechanism to release said lip to its depending position upon said downward return of said deck to said predetermined lower position; said lip extending means comprising linkage means connected between said deck, fixed structure and lip to effect positive outstanding movement of the latter upon upward deck movement to a predetermined upper position and positive retracing link movement upon downward deck movement to a predetermined lower position; and additional lip extending means comprising additional linkage means connected between said deck, fixed structure and lip to effect outstanding movement of the latter upon upward deck movement, said additional linkage means being resiliently biased to effect lip extension, and cam means operatively associated with said additional linkage means to hold the latter against said resilient biasing, said additional linkage means being freely telescopic in one direction to render said additional lip extending means ineffective to retract said lip.

h. A dock leveler according to claim 7, said holding mechanism comprising a linkage swingable into andout of a limited over-center position with said lip outstanding.

9. A dock leveler according to claim d, said linkage comprising a pair of links having their adjacent ends pivotally connected together and having their distal ends respectively pivoted to said lip and deck, and stop means carried by one of said links and engageable with the other of said links to limit relative swinging to said over-center position.

10. A dock leveler according to claim 9, said actuating means comprising an abutment located to displace said links out of their over-center position upon downward deck movement to a predetermined position.

1 1. A dock leveler according to claim 1, further comprising means for automatically returning said dock leveler to a substantially level position.

12. A dock leveler according to claim 11, wherein said means for automatically returning said dock leveler to a substantially level position comprising linkage means and a cam follower arm having a roller at one end and cam means for operatively returning said deck leveler to a positive, locked, and substantially level position.

13. A dock leveler according to claim 12, wherein said cam means is a ramp.

14. A dock leveler according to claim 12, wherein said cam follower arm is pivotally mounted intermediate the roller end and the other end of said cam follower arm.

15. A dock leveler according to claim 14, wherein said other end of said cam follower arm is pivotally connected to said linkage means.

16. A dock leveler according to claim 15, wherein said linkage means comprising a link pivotally connected to an arm cooperatively associated with said lip. and tension means connected to a fixed position and to an outer end of an arm fixed intermediate said follower arm, whereby upon said lip being dropped, said deck is returned to a positive, locked, level position.

Claims (16)

1. A dock leveler comprising a fixed structure, a deck having one end pivoted to said structure for swinging up and down movement of its other end, a lip pivoted to said other deck end for movement with said deck and swinging movement relative thereto between outstanding and depending positions, a holding mechanism connected to said lip and deck to hold said lip in its outstanding position and release said lip to its depending position, lip extending means connected to said lip to move the latter to its outstanding position upon upward deck movement, said holding mechanism serving to hold said lip in its outstanding position upon said upward deck movement and downward return of said deck to a predetermined lower position, actuating means located for operative actuation of said holding mechanism to release said lip to its depending position upon said downward return of said deck to said predetermined lower position; said holding mechanism comprising a linkage swingable into and out of limited over-center position with said lip outstanding to positively retain the latter outstanding; said linkage comprising a pair of links having their adjacent ends pivotally connected together and having their distal ends respectively pivoted to said lip and deck, and stop means carried by one of said links and engageable with the other of said links to limit relative swinging movement to said over-center position; and said actuating means comprising an abutment located to displace said links out of their over-center position upon downward deck movement to said predetermined lower position.

2. A dock leveler according to claim 1, said lip extending means comprising a crank arm pivotally carried by said deck and operatively connected to said lip for swinging the latter upwardly upon pivotal movement of said crank arm, and operating means connected between said crank arm and structure to operate the lip extending means on upward swinging movement of said deck.

3. A dock leveler according to claim 1, said abutment comprising a leg depending from one of said links adjacent to said adjacent link ends for abutting engagement with the nether fixed structure to effect said displacement.

4. A dock leveler according to claim 1, said lip extending means comprising linkage means connected between said deck, fixed structure and lip to effect outstanding movement of the latter upon upward deck movement, said linkage means being resiliently biased to effect yieldable lip extension, and cam means operatively associated with said linkage means to hold the latter against said resilient biasing.

5. A dock leveler according to claim 4, said linkage means being freely telescopic in one direction to render said lip extending means ineffective to retract said lip.

6. A dock leveler according to claim 1, said lip extending means comprising linkage means connected between said deck, fixed structure and lip to effect positive outstanding movement of the latter upon upward deck movement to a predetermined upper position and positive retracing link movement upon downward deck movement to a predetermined lower position.

7. A dock leveler comprising a fixed structure, a deck having one end pivoted to said structure for swinging up and down movement of its other end, a lip pivoted to said other deck end for movement with said deck and swinging movement relative thereto between outstanding and depending positions, a holding mechanism connected to said lip and deck to hold said lip in its outstanding position and release said lip to its depending position, lip extending means connected to said lip to move the latter to its outstanding position upon upward deck movement, said holding mechanism serving to hold said lip in its outstanding position upon said upward deck movement and downward return of said deck to a predetermiNed lower position, actuating means located for operative actuation of said holding mechanism to release said lip to its depending position upon said downward return of said deck to said predetermined lower position; said lip extending means comprising linkage means connected between said deck, fixed structure and lip to effect positive outstanding movement of the latter upon upward deck movement to a predetermined upper position and positive retracing link movement upon downward deck movement to a predetermined lower position; and additional lip extending means comprising additional linkage means connected between said deck, fixed structure and lip to effect outstanding movement of the latter upon upward deck movement, said additional linkage means being resiliently biased to effect lip extension, and cam means operatively associated with said additional linkage means to hold the latter against said resilient biasing, said additional linkage means being freely telescopic in one direction to render said additional lip extending means ineffective to retract said lip.

8. A dock leveler according to claim 7, said holding mechanism comprising a linkage swingable into and out of a limited over-center position with said lip outstanding.

9. A dock leveler according to claim 8, said linkage comprising a pair of links having their adjacent ends pivotally connected together and having their distal ends respectively pivoted to said lip and deck, and stop means carried by one of said links and engageable with the other of said links to limit relative swinging to said over-center position.

10. A dock leveler according to claim 9, said actuating means comprising an abutment located to displace said links out of their over-center position upon downward deck movement to a predetermined position.

11. A dock leveler according to claim 1, further comprising means for automatically returning said dock leveler to a substantially level position.

12. A dock leveler according to claim 11, wherein said means for automatically returning said dock leveler to a substantially level position comprising linkage means and a cam follower arm having a roller at one end and cam means for operatively returning said deck leveler to a positive, locked, and substantially level position.

13. A dock leveler according to claim 12, wherein said cam means is a ramp.

14. A dock leveler according to claim 12, wherein said cam follower arm is pivotally mounted intermediate the roller end and the other end of said cam follower arm.

15. A dock leveler according to claim 14, wherein said other end of said cam follower arm is pivotally connected to said linkage means.

16. A dock leveler according to claim 15, wherein said linkage means comprising a link pivotally connected to an arm cooperatively associated with said lip, and tension means connected to a fixed position and to an outer end of an arm fixed intermediate said follower arm, whereby upon said lip being dropped, said deck is returned to a positive, locked, level position.

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