US3500486A

US3500486A - Balancing means,lip actuating,locking and supporting means for dockboard assembly

Info

Publication number: US3500486A
Application number: US683657A
Authority: US
Inventors: Robert L Le Clear
Original assignee: T AND S EQUIPMENT Co
Current assignee: T AND S EQUIPMENT Co
Priority date: 1967-11-16
Filing date: 1967-11-16
Publication date: 1970-03-17
Anticipated expiration: 1987-03-17

Description

March 17, 1970 R. L. LE CLEAR 3,500,486

BALANCING MEANS, LIP ACTUATING, LOCKING AND SUPPORTING Filed Nov. 16, 1967 MEANS FOR DOCKBOARD ASSEMBLY 2 Sheets-Sheet 1 //VVEN7'0Z, 5% H1 fosarerl. [ECZEAE BY rims,- (M 5% KTTOENEYS March 17, 1970 R. L. LE CLEAR 3,500,436

BALANCING MEANS, LIP ACTUATING, LOCKING AND SUPPORTING MEANS FOR DOCKBOARD ASSEMBLY Filed Nov. 16, 1967 2 Sheets-Sheet 2 ATTOIEWEYS United States Patent M 3,500,486 BALANCING MEANS, LIP ACTUATING, LOCKING AND SUPPORTING MEANS FOR DOCKBOARD ASSEMBLY Robert L. Le Clear, Albion, Mich., assignor to T & S Equipment Co., Albion, Mich., a corporation of Michigan Filed Nov. 16, 1967, Ser. No. 683,657 Int. Cl. E01d 15/04; B65g 11/12 US. CI. 14-71 16 Claims ABSTRACT OF THE DISCLOSURE A dockboard assembly comprising a deck and a hinged lip is disclosed, the deck being substantially counterbalanced throughout all raised positions thereof when the hinged lip is in a dependent position. When the hinged lip itself is raised, the deck ceases to be balanced and drops until the hinged lip comes into contact with the vehicle to be loaded or unloaded.

Pivotal support means are provided for supporting the hinged lip in its dependent position and thus the deck member in a cross-traflic or below cross-traffic position. Means are also provided to lock the hinged lip member in its dependent position.

This invention relates to dockboard assemblies and relates more particularly to a device for use with a loading platform which includes a pivotally supported deck member or ramp having a lip element hingedly secured to its free end. Dockboards are commonly used with a fixed loading platform to compensate for the difference in height between the loading platform and a truck or other vehicle which is to be loaded or unloaded therefrom. The deck member or ramp of the dockboard is hinged at one end to permit swinging movement of the opposite end to accommodate the varying height of the vehicle. A lip element is hinged to the opposite end of the deck member to permit initial unloading of a vehicle by a fork lift or the like with the lip element in a dependent position and subsequent extension of the lip element into contact with the vehicle for further unloading.

The deck member or ramp of such dockboard assemblies are relatively heavy and, therefore, in the absence of any counter-balancing means, are difficult to lift above the generally level or cross-traffic position, a procedure which is necessary in order to clear the vehicle when the lip element is to be extended. Various counterbalancing means have been utilized heretofore, but ordinarily, such means have been relatively complex from a structural standpoint whereby they add excessive cost to the dockboard assembly and require frequent maintenance. Further, such prior art constructions have failed to compensate for the difference in counterbalancing force required by the variation in moment of the deck member as the same is lifted above the cross-traflic position. Thus, with arrangements utilized heretofore, it has been diflicult to maintain a nearly balanced condition for the deck member regardless of its relative position.

A further area of difficulty with prior art dockboard assemblies is encountered in the mechanisms utilized for moving the lip element between its dependent position and its extended position. It is ordinarily not necessary to fix or look the lip element in its extended position since in such position the lip element ordinarily rests on the vehicle. However, in the dependent position movement of the deck member can cause the lip element to swing free whereby either the lip element or the vehicle being loaded or unloaded can be damaged.

Additionally, when the lip element is in the dependent 3,500,486 Patented Mar. 17, 1970 position, the nearly balanced condition of the deck member is disturbed by any additional weight thereon. Since the loading dock is ordinarily utilized with the deck member in the cross-traflic position, it becomes highly desirable to provide a means for supporting the deck member in this position regardless of the weight thereon. Yet, under some circumstances, it is desirable for the deck member to be able to move to a position below level whereby any fixed stop or supporting element for retaining the deck member in its cross-traffic position would hinder such below level movement. Therefore, it becomes important to be able to provide a support for the cross-trafiic position of the dockboard assembly which can be selectively removed from supporting relationship in order to permit movement of the deck member to a position below level.

Considering the foregoing, it is a primary objective of the instant invention to provide a dockboard assembly which overcomes the various disadvantages of prior art constructions mentioned hereinabove, and others. Further, in this regard, it is an important feature of the instant invention to overcome such disadvantages in a simple and inexpensive manner utilizing noncomplex structures in order to avoid excessive maintenance costs. With this in mind, the instant invention provides means for effecting all of the desirable functional capabilities of a dockboard assembly such as those mentioned previously with purely mechanical elements thereby precluding the additional expense and maintenance problems resulting from the use of prior art constructions incorporating hydraulic cylinders or electrical motors.

More specifically, the instant invention has as one of its primary objects a counterbalancing mechanism which functions to permit relatively equal ease in movement of the deck member regardless of its position in relation to its hinged support. Thus, the counterbalancing means of the instant invention includes a relatively simple and inexpensive cam which is fixed directly or indirectly to the underside of the deck member in order to compensate for differences in the moment of the deck member or variations in the balancing force provided by a spring support, caused by movement of the deck member away from its cross-traffic position. The design and arrangement of the dockboard assembly of the instant invention is such that, although the deck member is nearly balanced by the counterbalancing means when the lip element is in its dependent position, extension of the lip element with respect to the deck member disturbs this nearly balanced condition and causes downward movement of the deck member until the lip element comes to rest on a vehicle which is .to be loaded or unloaded.

Yet another objective of the instant invention is the provision of a means which, while normally urging the lip element to its extended position, provides a relatively noncomplex mechanism for pulling the lip element into a dependent position and an overcenter locking means for securing the lip element in the dependent position.

Additionally, the instant inventive concepts contemplate the provision of a pivoting cross-trafiic support which includes a support element normally biased in a manner so as to underlie the lip element when the lip element is in the dependent position and when the deck member is in the cross-traflic position. However, the cross-traffic support means may be selectively moved to a position wherein it is not engaged by the lip element in order that the deck member may be dropped to a position below level when desired.

Other and further objects of the instant invention reside in the combination of elements, arrangement of parts and features of construction. Still other objects will in part be obvious and in part be pointed out as the de- 3 scription of the invention proceeds and as shown in the accompanying drawings wherein:

FIGURE 1 is a cross-sectional view through one em bodiment of a dockboard assembly according to the instant inventive concepts showing the same cooperating with the loading platform, with parts broken away for illustrative clarity and with a below-level position of the deck member and an extended position of the lip element being shown in dotted lines;

FIGURE 2 is a view similar to FIGURE 1 showing the deck member in an above-level position with the lip element extended;

FIGURE 3 is a fragmentary cross-sectional view particularly illustrating the use of a pivoting cross traflic support according to the instant invention, with the withdrawn relationship of the support being shown in dotted lines and with the extreme downward position of the deck member also being shown in dotted lines;

FIGURE 4 is a view similar to FIGURE 1 showing in detail a lip actuating and locking means for use with a dockboard assembly according to the instant invention,

with the lip element in the extended position with respect to the deck member; and

FIGURE 5 is a view of the dockboard assembly showing the relationship of the parts of the lip actuating and locking means when the lip element is locked in the dependent position with relation to the deck member,

Like reference characters refer to like parts throughout the several views of the drawings.

Referring now to the drawings, and more particularly to FIGURES 1 and 2, a dockboard assembly according to one embodiment of theinstant inventive concepts is designated generally by the reference numeral and is shown as associated with a loading dock designated generally by the reference numeral 12. The dockboard assembly 10 is shown as including a frame means 14 fixedly secured within a pit located in a loading dock, although it is to be understood that the dockboard assembly of the instant invention can be self-supported or otherwise positioned for use with a loading dock. The deck member 16 of the dockboard assembly 10 is operatively connected to a portion of the frame means 14 by a deck hinge means 18 which, as shown, may be slot type or lost motion hinges to compensate for canted or out-of-level trucks permitting tilting of the deck member 16 in either direction about a longitudinal central axis. The deck hinge means 18,'in any event, provides a substantially horizontal axis for pivoting of the deck member 16 between-a generally level or cross-traffic position as shown in full lines in FIGURE 1, a below-level position as shown in dotted lines in FIGURE 1 and an above-level position as shown in FIGURE 2.

A lip element 20 is pivotally secured to the free end of the deck member 16 by a lip hinge means 22 for movement of the lip element 20 about a substantially horizontal axis between a dependent position with respect to the deck member 16 as shown in full lines in FIGURE 1 and an extended position with respect to the deck member as shown in dotted lines in FIGURE 1 and in full lines in FIGURE 2.

The dockboard assembly 10 of the instant invention further includes a counterbalancing means designated generally by the reference numeral 25 and comprising basically a variable cam means 26 fixedly secured to the underside of the deck member 16, a cam follower means 28 including a roller 30 rotatably supported on one end of a cam follower arm 32 and ridingly engaging the camming surface 34 of the cam 26, the opposite end of the cam follower arm 32 being fixedly secured to a rotatably supported counterbalancing shaft 36 to which is also fixedly secured, spring mounting levers 38 which carry one end of a counterbalancing spring means 40 adjustably secured at the other end to a portion of the frame means 14, specifically, the bracket member 42.

It is to be understood that the construction shown in the drawings only illustrates one section through a dockboard assembly of the type with which the instant invention is concerned. Obviously, there must be deck hinge means on either side of the deck member. Additionally, a plurality of counterbalancing springs are ordinarily operatively secured to a plurality of spring mounting levers carried by the counterbalancing shaft in order to provide sufficient counterbalancing force for the weight of the deck member. Usually, a single cam and cam follower means, positioned centrally of the deck member is adequate, although a plurality of such elements may be utilized, if desired. Oppositely disposed bearing means may be used to rotatably support a solid counterbalancing shaft or the counterbalancing shaft may include a sleeve rotatably carried on a fixed bearing rod as shown in the drawings, with the cam follower arm and the spring mounting levers fixedly secured to the sleeve.

The tension of the counterbalancing springs 40 is transferred through the spring mounting levers 38, the counterbalancing shaft 36 and the cam follower arm 32 to the roller 30 which provides a counterbalancing force against the camming surface 34 to nearly balance the moment of the deck member 16 with the lip element 20 in the dependent position. Of course, when the lip element 20 is moved to its extended position, this nearly balanced condition is disturbed and the deck member 16 seeks its lowest level.

However, with the lip element 20 in the dependent position, the variable cam means 26 produces a substantially constant deck weight since the curve of the camming surface 34 has been determined by the force differential resulting from biasing the deck in different planes. Thus, the camming surface compensates for changes in the counterbalancing force needed to maintain the nearly balanced condition as a result of changes in the moment of the deck member and variations in the counterbalancing effect of the counterbalancing spring means caused by movement of the deck member about the deck hinge means. This use of tension springs in combination with a single variable cam eliminates more complex prior art counterbalancing means and permits adjustment of the weight to be lifted with ordinary tools.

A fixed stop member 44 may be carried beneath the deck member 16 for engaging a portion of the deck member, in the embodiment shown, the element 46, when the deck member has reached its lowest level. However, if desired, a pivoting cross-traflic support such as designated generally by the reference numeral 50 in FIGURE 3 may also be utilized. The pivoting cross-traflic support means includes one or more support elements 52 pivotally secured as at 54 to a portion of the frame means 14 with a torsion spring 56 normally urging the support member 52 to the full line position as shown in FIGURE 3 wherein a portion of the support member 52 underlies the lip element 20 when the lip element is in the dependent position and when the deck member is in the cross traffic position. In this manner, the deck member 16 may be supported in the cross-traffic position for normal use. When it is desired to permit the deck member to descend to a below-level position, the support member 52 may be pivoted by any desired means such as the flexible cable shown illustratively at 56 to a position wherein it does not underlie the lip element 20. Once the deck member has been lifted sufliciently for the lip element to bypass the support member 52, the torsion spring means 56 automatically returns the support member to the operative relationship shown in full lines in FIGURE 3 so as to again support the deck member in the cross-traffic position. When the pivoting support means is withdrawn the deck member will descend until the lip element 20 is supported on a vehicle or until a portion of the deck member such as the element 46 comes to rest on the fixed stop element 44.

Reference is now made to FIGURES 4 and 5 for a more detailed description of the lip actuating and locking means of the instant invention, designated generally by the reference numeral 60. Basically, the lip actuating and locking means functions to selectively lock the lip element 20 in the dependent position as shown in FIGURE 5 and, on release of the locking means, the lip actuating and locking means 60 automatically biases the lip element 20 to the extended position such as shown in FIGURE 4.

The lip actuating and locking means 60 includes a fulcrum lever 62 pivotally supported by a pin means 64 intermediate its ends, the pin means being carried by a bracket or the like 66 secured to the underside of the deck member 16. A transfer linkage 68 pivotally interconnects one end of the fulcrum lever 62 with one end of a rigid lever 70, the opposite end of which is fixedly secured to the lip hinge means 22 for rotation of the lip element 20 thereabout. The opposite end of the fulcrum lever 62 is pivotally connected to one end of a pivoting linkage designated generally by the reference numeral 72 and comprising basically a pair of

link sections

74, 76 pivotally interconnected as shown at 78. The opposite end of the pivoting linkage 72 is pivotally secured to the underside of the deck member 16 as shown at 80.

counterclockwise rotation of the fulcrum lever 62 about the pin means 64 automatically raises the lip element 20 to the extended position shown in FIGURE 4. Conversely, clockwise rotation of the fulcrum lever 62 about the pin means 64 automatically lowers the lip element 20 to the dependent position shown in FIGURE 5.

When the included angle defined between the

link sections

74, 76 of the pivoting linkage 72 is less than 180 degrees as shown, for example, in FIGURE 4, the fulcrum lever 62 is normally biased in a counterclockwise direction by a lip-actuating spring means 82 which is se cured at one end to the fulcrum lever 62 below the pin means 64 and is adjustably secured at its other end to the underside of the deck member 16, specifically, in the embodiment shown, to the bracket member 84. This insures that the lip element 20 is normally biased toward the extended position, the biasing force being readily adjusted by modifying the length of the lip-actuating spring means 82.

When the included angle defined by the

link sections

74, 76 of the pivoting linkage 72 slightly exceeds 180 degrees, the lip element 20 is pulled into the fully dependent position as shown in FIGURE 5. The

link sections

74, 76 are secured in this overcenter relationship by a stop means in the form a bent element 86 secured to one link section, in the illustrated embodiment, 74, engaging the other link section 76. This overcenter relationship of the pivoting linkage 72 in combination with the tension exerted by the lip-actuating spring means 82 looks the lip element 20 in the dependent position.

In order to move the

link sections

74, 76 of the pivoting linkage 72 between the relationship shown in FIGURE 4 and the overcenter relationship shown in FIGURE 5, an actuating means must be provided to overcome the tension of the lip-actuating spring means 82. One form of illustrative actuating means is shown in FIGURES 4 and 5 as including a link element 88 pivotally secured to the pivoting linkage 72 intermediate its ends and rotatably carrying a sheave 90. Flexible means in the form of a cable or the like 92 are secured at one end 94 to the underside of the deck member 16 and trained over the sheave 90 to provide a free end 96 which can have a finger engaging eye 98 seated in a well 100 for access from above the deck member 16. An idler roller 102 may be provided to guide the flexible means 92 to the well 100. By pulling the free end of the flexible means 92 in an upward direction the pivoting linkage 72 will be drawn to its overcenter relationship and the lip element 20 will be locked in its dependent position.

Various releasing means may be utilized for breaking the overcenter relationship and permitting the lip-actuating spring means 82 to bias the lip element 20 to the extended position shown in FIGURE 4. One such releasing means is shown in full lines in FIGURE 5 as a flexible means 104, such as a cable or chain, one end 106 of which is fixedly secured such as to the frame means 14 or the like with the other end 108 being secured to the pivoting linkage 72. The flexible means 104 is so dimensioned that when the deck member 16 has been raised to a predetermined degree above the cross traffic position, the flexible means 104 becomes taut and pulls the pivoting linkage to break the overcenter relationship.

An additional releasing means is shown in dotted lines in FIGURE 5 as a flexible means such as a cable or the like 110 secured at one end to the pivoting linkage 72 and trained over a sheave 112 rotatably carried by the frame means 14. On pulling of the free end 114 of the flexible means 110, which may have an eye or the like (not shown) seated in a well (not shown) for accessibility from above the deck member, the overcenter relationship of the pivoting linkage 72 is broken and the lipactuating spring means 82 is free to effect movement of the lip element 20 to the extended position as shown in FIGURE 4.

The use and operation of the dockboard assembly of the instant invention will now readily 'be understood. First of all, it should be emphasized that the dockboard assembly including all of the various features described hereinabove and shown in the drawings is particularly desirable, although the various features may find separate utility in any dockboard construction. For example, the variable cam counterbalancing means may be utilized with or without the pivoting cross traffic support and with or without the lip actuating and locking means. Similarly, the pivoting cross triffic support and/ or the lip actuating and locking means may be utilized with dockboard assemblies having other counterbalancing means or no counterbalancing means at all. However, in use of a combined construction, the deck member 16 is maintained in a nearly balanced condition when the lip element 20 is in the dependent position by a counterbalancing force provided by the counterbalancing spring means 40. The specially designed camming surface 34 on the cam means 26 compensates for changes in the moment of the deck member 61 and variations in the counterbalancing effect of the counterbalancing spring means 40 caused by movement of the deck member 16 from the cross-traflic position. Thus, the effective weight of the deck member 16 for lifting purposes remains substantially constant regardless of the position of the deck member in relation to the deck hinge means 18. However, on movement of the lip element 20 to the extended position with relation to the deck member 16, the nearly balanced condition is disturbed and the deck member 16 will drop until the lip element 20 engages a vehicle or a portion of the deck member 16 engages the fixed stop 44.

In order to maintain the deck member 16 in the crosstraffic position regardless of the weight thereon a portion of the support member 52 extends into the path of travel of the lip element 20 when the lip element 20 is in its dependent position and when the support member 52 is in its normally biased relationship. On rotation of the support member 52 about the pin means 54 against the force of the torsion spring means 56, the lip element 20 bypasses the support member 52 and the deck member 16 is free to drop below the cross-traflic position. The deck member 16, in its lowest position, will come to rest on the fixed stop 44. This construction enables the deck member to support itself in a position below the level of the loading dock with or without the lip element resting on a vehicle. Thus, the rearmost pallets of a vehicle whose bed height is lower than the loading dock may be loaded or unloaded with the lip element in a dependent position following which the lip element can be extended into the cargo area of the vehicle for further loading or unload ing.

The lip element is normally maintained in the extended position by the lip-actuating spring means 82 which functions to rotate the fulcrum lever -62 in a counterclockwise direction when the

link sections

74, 76 of the pivoting linkage 72 define an included angle of less than 180 degrees. In order to pull the lip element 20 to the dependent position and lock the same in the dependent position, the pivoting linkage 72 may be engaged in the overcenter relationship by pulling the flexible means 92 to increase the angle included between the

link sections

74, 76 to slightly over 180 degrees at which point the stop means 86 precludes further movement of the pivoting linkage 72 and locks the same in the overcenter relationship. The overcenter relationship is broken either automatically by utilizing a flexible means such as shown at 104 which is dimensioned to become taut when the deck member 16 has been raised to a predetermined degree above the crosstraffic position, or 'by a manually engaged flexible means such as shown at 110 which functions to pull the pivoting linkage to a relationship wherein the included angle between the

link sections

74, 76 is less than 180 degrees at which point the lip-actuating spring means 82 is free to effect movement of the lip element 20 to the extended position.

Thus, it will now be seen that here is herein provided an improved dockboard consruction which is simple and inexpensive and yet, which functions in an admirable manner to provide a highly versatile device. The dockboard assembly costruction of the instant invention thereby satisfies all of the objectives set forth hereinabove, and others, including many advantages of great practical utility and commercial importance.

Since many embodiments may be made of the instant inventive concepts, and since many modifications may be made of the embodiments hereinbefore shown and described, it is to be uderstood that all matter herein is to be interpreted merely as illustrative and not in a limiting sense.

What is claimed is:

1. In a dockboard assembly including a frame means, a deck member, deck hinge means operatively secured in one end of said deck member to said frame means for pivoting of said deck member about a substantially horizontal axis, between a generally level position, a position below level and a position above level, and counterbalancing means for said deck member, the improvement which comprises a lip element, lip hinge means operatively connecting said lip element with the other end of said deck member for pivoting of said lip element about a substantially horizontal axis between a dependent position with respect to said deck member and an extended position with respect to said deck member,- locking means for selectively locking said lip element in said dependent position and biasing means for urging said lip element toward said extended position when said locking means are released, and wherein said counterbalancing means for said deck member substantially balances said deck member in all pivotal positions a'bove level when said lip element is in said dependent position, and wherein said lip element projects beyond said other end of said deck member in said extended position thereof so as to increase the moment of said deck member about said deck hinge means thereby overriding said counterbalancing means and causing said deck member to move downwardly about said deck hinge means when said lip element is in said extended position, said counterbalancing means including cam means fixedly secured to the underside of said deck member at a location spaced from one end thereof, said cam means defining a variable camming surface, cam

follower means including a roller ridingly engaging said camming surface, and counterbalancing spring means operatively associated with said cam follower means to maintain said roller in riding engagement with said camming surface and to provide a counterbalancing force, said camming surface defining a curve determined by the force differential resulting from biasing said deck member in different planes so as to compensate for changes in the counterbalancing force needed as a result of changes in the moment of said deck member and variations in the counterbalancing effect of said counterbalancing spring means caused by movement of said deck member about said deck hinge means.

2. The dockboard assembly of claim 1 wherein said counterbalancing means further includes a rotatably supported counterbalancing shaft, at least one spring mounting lever secured to said counterbalancing shaft for rotation therewith, said counterbalancing spring means including at least one counterbalancing spring member having one end secured to said frame means and its other end secured to said spring mounting lever, said cam follower means including at least one cam follower arm secured to said counterbalancing shaft for rotation therewith, and said roller being rotatably carried by the other end of said cam follower arm.

3. The dockboard assembly of claim 2 further including adjusting means operatively connected to said one end of said counterbalancing spring member for varying the tension thereon thereby varying said counterbalancing force.

4. The dockboard assembly of claim 1 wherein said biasing means includes a fulcrum lever, pin means carried beneath said deck member and pivotally supporting said fulcrum lever intermediate the ends of said fulcrum lever, linkage means operatively interconnecting one end of said fulcrum lever with said lip element, and lip-actuating spring means operatively connected to the other end of said fulcrum lever for normally pivoting said fulcrum lever about said pin means in a direction to actuate said linkage means for urging said lip element toward said extended position.

5. The dockboard assembly of claim 1 further including support means engaged by the free end of said lip element when said lip element is in said dependent position and said deck member is in said generally level position.

6. The dockboard assembly of claim 5 wherein said support means includes a support member rotatably carried by said frame means for movement between a first position wherein a portion of said support member extends beneath the downward path of travel of said lip element and supportingly engages said lip element when said lip element is in said dependent position and said deck member is in said generally level position, and a second position wherein said support member is out of the downward path of travel of said lip element whereby said lip element is free from engagement by said support element and said deck member can move downwardly below said generally level position, and torsion spring means resiliently urging said support member toward said first position.

7. The dockboard assembly of claim 6 further including a fixed stop element secured to said frame means out of the downward path of travel of said lip element but in the downward path of travel of a portion of said deck member, whereby, when said support member is in said second position, said portion of said deck member engages said stop element for support of said deck member when said deck member has been lowered to a predetermined degree below said generally level position.

8. In a dockboard assembly including a frame means, a deck member, deck hinge means operatively securing one end of said deck member to said frame means for pivoting of said deck member about a substantially horizontal axis, between a generally level position, a position below level and a position above level, and count rbalancing means for said deck member, the improvement which comprises said counterbalancing means including cam means fixedly secured to the underside of said deck member at a location spaced from said one end thereof, said cam means defining a variable camming surface, cam

follower means including a roller ridingly engaging said camming surface, and counterbalancing spring means operatively associated with said cam follower means to maintain said roller in riding engagement with said camming surface and to provide a, counterbalancing force for at least nearly balancing said deck member, said camming surface being so designed and arranged as to compensate for changes in the counterbalancing force needed as a result of changes in the moment of said deck member and variations in the counterbalancing effect of said counterbalancing spring means caused by movement of said deck member about said deck hinge means, said dockboard assembly further including a lip element, lip hinge means operatively connecting said lip element with the other end of said deck member for pivoting of said lip element about a substantially horizontal axis between a dependent position with respect to said deck member and an extended position with respect to said deck member, said deck member being at least nearly balanced by said c'ounterbalancing force when said lip element is in said dependent position, and said lip element projecting beyond said other end of said deck member in said extended position so as to increase the moment of said deck member about said deck hinge means thereby overriding said counterbalancing force and causing said deck member to move downwardly about said deck hinge means when said lip element is in said extended position, further including locking means operatively associated with said lip element for locking said lip element in said dependent position, releasing means for releasing said locking means, and biasing means actuable on release of said locking means for urging said lip element toward said extended position, wherein said biasing means includes a fulcrum lever, pin means carried beneath said deck member and pivotally supporting said fulcrum lever intermediate the ends of said fulcrum lever, linkage means operatively interconnecting one end of said fulcrum lever with said lip element, and lip-actuating spring means operatively connected to the other end of said fulcrum lever for normally pivoting said fulcrum lever about said pin means in a direction to actuate said linkage means for urging said lip element toward said extended position, and wherein said locking means includes a pivoting linkage comprising a pair of pivotally interconnected link sections, one end of said pivoting linkage being pivotally connected to said other end of said fulcrum lever and the other end of said pivoting linkage being pivotally carried beneath said deck member, said pivoting linkage and said lip-actuating spring means being so dimensioned that when the included angle defined between said link sections is less than 180 degrees, said lipactuating spring means operates to bias said lip element toward said extended position and when said pivoting linkage passes through an overcenter relationship and said included angle defined between said link sections slightly exceeds 180 degrees, said fulcrum lever is pivoted about said pin means in a direction to actuate said linkage means for pulling said lip element to said dependent position, stop means carried by one of said link sections and engaging the other link section when said pivoting linkage passes through said overcenter relationship to lock said lip element in said dependent position, and actuating means operatively connected to said pivoting linkage for pulling said pivoting linkage to said overcenter relationship.

9. The dockboard assembly of claim 8 wherein said actuating means includes a link element pivotally secured to said pivoting linkage intermediate the ends of said pivoting linkage, a sheave rotatably carried by said link element, and flexible means fixedly secured at one end to said deck element and trained over said sheave whereby, pulling the other end of said flexible means, said pivoting linkage is pulled to said overcenter relationship and said lip element is locked in said dependent position.

10. The dockboard assembly of claim 8 wherein said releasing means includes a flexible means secured at one end to said frame means and secured at its other end to said pivoting linkage, said flexible means being so dimensioned as to break said overcenter relationship when said deck member has been raised to a predetermined degree above said generally level position whereby said lip-actuating spring means is free to effect movement of said lip element toward said extended position.

11. The dockboard assembly of claim 8 wherein said releasing means includes a sheave rotatably carried by said frame means, a flexible means secured at one end to said pivoting linkage and trained over said sheave whereby, on pulling the other end of said flexible means, said overcenter relationship is broken and said lip-actuating spring means is free to effect movement of said lip element toward said extended position.

12. In a dockboard assembly including a frame means, a deck member, deck hinge means operatively securing one end of said deck member to said frame means for pivoting of said deck member about a substantially horizontal axis between a generally level position, a position below level and a position above level, a lip element, and lip hinge means operatively connecting said lip element with the other end of said deck member for pivoting said lip element about a substantially horizontal axis between a dependent position with respect to said deck member and an extended position with respect to said deck member, the improvement which comprises locking means operatively associated with said lip element for locking said lip element in said dependent position, releasing means for releasing said locking means, and biasing means actuable on release of said locking means for urging said lip element toward said extended position, and wherein said biasing means includes a fulcrum lever, pin means carried beneath said deck member and pivotally supporting said fulcrum lever intermediate the ends of said fulcrum lever, linkage means operatively interconnecting one end of said fulcrum lever with said lip ele ment, and lip-actuating spring means operatively connected to the other end of said fulcrum lever for normally pivoting said fulcrum lever about said pin means in a direction to actuate said linkage means for urging said lip element toward said extended position, and wherein said locking means includes a pivoting linkage comprising a pair of pivotally interconnected link sections, one end of said pivoting linkage being pivotally connected to said other end of said fulcrum lever and the other end of said pivoting linkage being pivotally carried beneath said deck member, said pivoting linkage and said lip-actuating spring means being so dimensioned that when the included angle defined between said link sections is less than degrees, said lip-actuating spring means operates to bias said lip element toward said extended position and when said pivoting linkage passes through an overcenter relationship and said included angle defined between said link sections slightly exceeds 180 degrees, said fulcrum lever is pivoted about said pin means in a direction to actuate said linkage means for pulling said lip element to said dependent position, stop means carried by one of said link sections and engaging the other link section when said pivoting linkage passes through said overcenter relationship to lock said lip element in said dependent position, and actuating means operatively connected to said pivoting linkage for pulling said pivoting linkage to said overcenter relationship.

13. The dockboard assembly of claim 12 wherein said actuating means includes a link element pivotally secured to said pivoting linkage intermediate the ends of said pivoting linkage, a sheave rotatably carried by said link element, and flexible means fixedly secured at one end to said deck element and trained over said sheave whereby, by pulling the other end of said flexible means, said pivoting linkage is pulled to said overcenter relationship and said li-p element is locked in said dependent position.

1 l 14. The dockboard assembly of claim 12 wherein said releasing means includes a flexible means secured at one end to said frame means and secured at its other end to said pivoting linkage, said flexible means being so dimensioned as to break said overcenter relationship when said deck member has been raised to a predetermined degree above said generally level position whereby said lipactuating spring means is free to eflect movement of said lip element toward said extended position.

15. The dockboard assembly of claim 12 wherein said releasing means includes a sheave rotatably carried by said frame means, a flexible means secured at one end to said pivoting linkage and trained over said sheave whereby, on pulling the other end of said flexible means, said overcenter relationship'is broken and said lip-actuating spring means is free to effect movement of said lip element toward said extended position.

16. In a dockboard assembly including a frame means, a deck member, deck hinge means operatively securing one end of said deck member to said frame means for pivoting of said deck member about a substantially horizontal axis between a generally level position, a position below level and a position above'level, a lip element, and lip hinge means operatively connecting said lip element with the other end of said deck member for pivoting said lip element about a substantially horizontal axis between a dependent position with respect to said deck member and an extended position with respect to said deck member,

the improvement which comprises support means engaged by the free end of said lip element when said lip element is in said dependent position and said deck member is in said generally level position, and wherein said support means includes a support member'rotatably carried by said frame means for movement between a first position wherein a portion of said support member extends beneath the downward path of travel of said lip element and supportingly engages said lip element when said lip element is in said dependent position and said deck member is in said generally level position, and a second position wherein said support member is out of the downward path of travel of said lip element whereby said lip element is free from engagement by said support element and said deck member can move downwardly below said generally level position, and torsion spring means resiliently urging said support member toward said first position, said dockboard assembly further including a fixed stop element secured to said frame means out of the downward path of travel of said lip element but in the downward path of travel of a portion of said deck member, whereby, when said support member is in said second position, said portion of said deck member engages said stop element for support of said deck member when said deck member has been lowered to a predetermined degree below said generally level position.

References Cited UNITED STATES PATENTS 3,137,017 6/1964 Pfleger 14-71 3,203,002 8/1965 McGuire l471 3,323,158 6/1967 Loomis 147l 3,327,335 6/1967 Beckwith et al. 14--71 3,335,442 8/1967 Kumpolt 1471 JACOB L. NACKENOFF, Primary Examiner