US3249956A

US3249956A - Manually operated dockboard

Info

Publication number: US3249956A
Application number: US316335A
Authority: US
Inventors: Anthony J Zajac; Amico Alfred E De
Original assignee: American Welding & Engineering
Current assignee: American Welding & Engineering; American Welding & Engineering Co Inc
Priority date: 1963-10-15
Filing date: 1963-10-15
Publication date: 1966-05-10
Anticipated expiration: 1983-05-10

Description

y 10, 1966 A. J. ZAJAC ETAL 3,249,956

MANUALLY OPERATED DOCKBOARD Filed Oct. 15, 1963 8 Sheets-Sheet INVENTORS May 10, 1966 A. J. zAJAc ETAL MANUALLY OPERATED DOCKBOARD 8 Sheets-Sheet 2 Filed Oct. 15, 1965 INVENTORS fl/vrHa/vvJ. 24.146 HLFZGED 5.0500044 May 10, 1966 A. J. ZAJAC ETAL MANUALLY OPERATED DOCKBOARD 8 Sheets-Sheet 3;.

Filed Oct. 15, 1965 IN VENTORS fi/vrHa/vv J. 2414a H A F5950 E. 059M150 y 1966 A. J. ZAJAC ETAL 3,249,956

MANUALLY OPERATED DOCKBOARD Filed Oct. 15, 1963 8 Sheets-Sheet 4 8 Sheets-Sheet 5 lLil: T511 1 1i A. J. ZAJAC ETAL MANUALLY OPERATED DOCKBOARD May 10, 1966 Filed Oct. 15, 1963 y 0, 1966 A. J. ZAJAC ETAL 3,249,956

MANUALLY OPERATED DOCKBOARD IN VENTORS 205 /'2 24 gA/THONY J. 24.19

Au-veso E. DEfi/waa May 10, 1966 A. J. ZAJAC ETAL 3,

MANUALLY OPERATED DOCKBQARD Filed Oct. 15, 1965 8 Sheets-Sheet 7 INVENTORS fl/wwam/ J- 29.11 m 94/ 650 E. DEB/ma:

ATTOEA/E Y5 May 10, 1966 A. J. ZAJAC ETAL 3,249,956

MANUALLY OPERATED DOCKBOARD Filed Oct. 15, 1963 8 Sheets-Sheet 8 I la f gaa INVENTORf I I IQ/VTHOIVY J. ZHJ/76 204 A FEEDE 0.54m,

AT'TO P/VEY} United States Patent 3,249,956 MANUALLY OPERATED DOCKBOARD Anthony J. Zajac and, Alfred E. De Amico, Milwaukee, Wis., assignors to American Welding & Engineering C0., Inc., Milwaukee, Wis., a corporation of Wisconsin Filed Oct. 15, 1963, Ser. No. 316,335 14 Claims. (Cl. 1471) This invention relates to improvements in adjustable loading ramps.

This application is a continuation in part of our copending application Serial No. 235,642, filed November 6, 1962 and now abandoned.

An important feature of the loading ramp of the present invention is the lip which is hinged to its foremost edge. The ramp has a foot actuated button or pedal by which the latch which normally holds the lip extended is manually released. In some prior art devices, the lip is released automatically as a consequence of the upward pres sure of its engagement with a truck bed. This has certain disadvantages which the manually releasable foot button overcomes. The foot operated button release mechanism for the lip incorporates novel structure which particularly adapts it for use in the loading ramp of the present invention.

Another important feature of the invention resides in an embodiment thereof incorporating torsion springs or bars to bias the ramp upwardly. The ramp mechanism a can be greatly simplified and its cost and maintenance reduced thereby.

Other features of the invention include yieldable mechanism to preclude damage to the ramp if a truck backs into .its extended lip, mechanism to permit the ramp to tilt to accommodate to a tilted truck bed and an improved ramp check mechanism including a toothed rack.

Other objects, features and advantages of the invention will appear from the following disclosure in which:

FIGURE 1 is a vertical cross section taken through an adjustable loading ramp embodying the invention, the ramp being shown in its fully elevated position.

FIGURE 2 is a similar view in vertical cross section showing the ramp after it has been walked down to engage its lip with a truck bed which happens to be below the level of the dock. t

FIGURE 3 is a fragmentary vertical cross section showing the ramp of FIGURE 2 after the truck of FIG. 2 has been unloaded and its springs have expanded to lift the ramp to an elevation higher than the level of the dock.

FIGURE 4 is a plan view of an adjustable loading ramp embodying the invention, the lip depending from the foremost edge of the ramp with the ramp in its cross traffic position. Portions of the ramp deck are broken away in this figure to expose details of one form of elevator arm and spring assembly.

FIGURE 5 is a vertical cross section taken through the ramp of FIGURE 4.

FIGURE 6 is a view partially in elevation and partially in section through the ramp check'or overrunning latch mechanism which opposes the bias of elevator mechanism.

FIGURE 7 is a cross section taken along the line 7-7 of FIGURE 6.

FIGURE 8 is an enlarged perspective view of the wedge lock roller and cam assembly also shown in FIG- URES 6 and 7.

FIGURE 9 is an enlarged fragmentary cross section taken through the ramp deck and hinged lip and showing 7 Patented May 10, 1966 ice FIGURE 11 is a fragmentary view similar to FIG- URE 9 but omitting some details and showing the foot actuated button in its depressed position. 7

FIGURE 12 is a vertical cross section at right angles to the cross section of FIGURE 9 and showing further details of the latch mechanism.

FIGURE 13 is a fragmentary inverted plan view of the ramp deck showing details of the latch mechanism.

FIGURE 14 is a bottom perspective view of the latch abutment block.

FIGURE 15 is a view similar to FIGURE 12 but show ing the push button depressed and the latch arm shifted into its released position.

. FIGURE 16 is an inverted plan view similar to FIG- URE 13 but showing the push button depressed and the latch arm shifted to its released position.

FIGURE 17 is a vertical cross section similar to FIG- URE 5, and showing a modified embodiment in which torsion springs constitute the ramp elevator.

FIGURE 18 is a rear elevation of the device of FIG- URE 17.

FIGURE 19 is a fragmentary plan view of the device of FIGURE 17, portions of the deck being broken away to expose details of construction.

FIGURE 20 is a vertical cross section similar to FIG- URES 5 and 17, and showing a still further modified.

embodiment of the invention. 1

FIGURE 21 is a fragmentary plan view of the device shown in FIGURE 20.

FIGURE 22 is a fragmentary rear perspective view of the device shown in FIGURE 20, the ramp being tilted with respect to its frame.

FIGURE 23 is a fragmentary perspective view of the undersurface of the ramp of the embodiment shown in FIGURE 20.

FIGURE 24 is a cross section taken along the line 24-24 of FIGURE 20, but showing the ramp deck tilted as shown in FIGURE 22 to accommodate to a canted,

truck bed.

FIGURE 25 is a fragmentary vertical cross section through the lip end of the ramp of the device shown in FIGURE 20, shown in association with a truck shown diagrammatically.

FIGURE 26 is an enlarged fragmentary view similar to that shown in FIGURE 25, but in which the foot-actuated latch release button is in its depressed position, further details of the latch arm being shown in cross section.

FIGURE 27'is a fragmentary cross section taken along the line 27-27 of FIGURE 26.

FIGURE 28 is a vertical cross section taken through the lip end of the loading ramp showing the lip in a series of different positions (shown in full and broken lines) under pressure of a backing truck.

FIGURE 29 is a fragmentary vertical cross section taken through the latch arm and its pivotal connection to the under-surface of the ramp.

FIGURE 30 is a fragmentary cross section taken through a modified form of ramp check showing its respective connections to the frame and to the ramp.

FIGURE 31 is a fragmentary view taken along the line 3131 of FIGURE 30.

FIGURE 32 is a cross section taken along the line 3232 of FIGURE 31.

FIGURE 33 is a fragmentary cross section taken through the lip end of the ramp showing the lip in its downwardly depending position.

FIGURE 34 is a fragmentary vertical cross section taken through the lip end of the ramp showing the lip in its elevated extending position.

FIGURE 35 is a fragmentary detail view of one of the adjustable safety support parts for the ramp deck.

Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. The scope of the invention is defined in the claims appended hereto.

Like parts are given the same reference characters in the several views.

According to the present invention the concrete dock is provided at each truck loading station with a recess 21in which a unitary frame 22 is mounted. Adjacent its rear-portion frame 22 is provided with upwardly projecting standards 24 having at their upper ends hinge pins 24 on which the ramp 25 is pivotally mounted. Ramp 25 constitutes a deck plate 26 suitably braced at its under surface by beams 27. In the embodiment of FIGURES 1-5, cross beam 30 of frame 22 provides a pivotal mounting for a pair of laterally spaced elevator arms 31, each of which may consist of spaced arm plates 32 cross-connected by suitable webs 33 and pins 34, etc. The cross beams 30 has upstanding brackets 35 to which the arms 31 are pivotally connected on pins 36. The otherwise free ends of the arms 31 are provided with cross shafts 38 having wheels 37 which are inshiftable and lost-motion contact with the under surface of the ramp deck 26.

Elevator arms 31 are biased to extert the upward pressure of their wheels 37 against the deck 26 by coil springs 40 interconnected between pin 34 and spring anchors 49 at the rear of frame 22. The bias of all four of the springs 40 shown in the embodiment of the invention shown in FIGURES 1-5 is sufiicient to lift the ramp 25 to its elevated position as shown in FIGURE 1 of the drawing.

The bias of two of the springs 40 is releasably opposed by the ramp check or overrunning latch mechanism 41, the details of which are best shown in FIGURES 6, 7 and 8. Ramp check 41 consists of relatively

slidable shoes

42, 43. Shoe 42 is pivotally connected on pin 44 to the frame 22. Shoe 43 is pivotally connected on pin 39 to one of the elevator arms 31. Shoe 42 has upstandinging side Wall plates 45 which provide a guideway between which shoe 43 slides.

Shoe 43 is further guided by roller 46 mounted on a 'shaft 47 which spans between the wall plates 45. Shoe 42 is desirably faced on its side toward shoe 43 with a brass wear plate 48. The surface of roller 46 is sufficiently spaced from the wear plate 48 to permit shoe 43 to freely slide therebetween.

Shoes

42, 43 can be releasably locked together in any position within the range of movement of the ramp 25 by a releasable wedge'lock mechanism which includes a roller 50. One portion of the roller periphery bears on the shoe 43 and an opposed portion of the roller eriphery bears on an inclined reaction wedge block 51.

Block 51 is pivotally mounted on pin 52 which spans between the wall plates 45. The degree of convergence of block 51 with respect to

shoes

42, 43 can be adjusted by the threaded bolt 53. Adjustment of the bolt 53 will change the point of co-action of the roller and the opposed surface of the wear plate 48 against the intervening shoe 43.

Wedge roller 50 is mounted on a carriage comprising side plates or arms 54 having enlarged end portions 55 which are provided with journal openings to receive an eccentrically mounted cam roller 56. Cam roller 56 has an axle pin 57 fixed thereto and which turns in suit,- able bearing openings formed in the wall plates 45. One end of the pin 57 projects beyond one of the walls 45 and is connected by the set screw 60 to lanyard crank or lever arm 61. Lanyard lever 61 is biased in counterclockwise direction, as view in FIGURE 6, by spring 52 which is connected between lever arm 61 and a fixed bracket 63. Lever 61 may be turned clockwise, as viewed in FIG- 4 URE 6, against the bias of spring 62 by pulling on the lanyard 64.

It is clear from FIGURE 6 that when the lanyard 64 is slack, spring 62 will urge lanyard lever 61 in counterclockwise direction, thus to rotate cam roller 56 in its bearings in the carriage arms 54 to urge wedge roller 50 along the inclined surface of the block 51, thus to assert braking pressure between the

shoes

42, 43. If the lanyard 64 is pulled to overcome the bias of spring 62, wedge roller 50 will be withdrawn rearwardly to release clamping pressure between the

shoes

42, 43.

Assuming the lanyard to be slack and the ramp to be in its elevated position as shown in FIGURE 1, the bias of springs 40 is such that if a man walks out on the ramp his weight in addition to that of the ramp will overcome the bias of the springs 40 and the ramp will descend under combined weight of the-man and the ramp. This descent is not impeded by the latching mechanism 41 because the tension of spring 62 is insuflicient to restrain closing movement of the

shoes

42, 43. The latching mechanism simply overruns in its closing direction. Closing movement will simply tend to move the roller 40 rearwardly away from wedging engagement between its block 51 and wear strip 48. However, with the lanyard still slack, the elevator arm 31 will be locked against upward movement because any such movement will assist the spring 61 in urging the wedge roller 50 into clamping engagement of the

shoes

42, 43. The mechanism will automatieally lock in its opening direction, unless the lanyard is taut.

The loading ramp 25 is provided along its foremost edge 65 with an extension lip 66 which is pivotally rnovable with respect to the ramp on piano-type hinge 67. Hinge 67 is mounted on a front apron strip 70, the top edge 71 of which serves as a stop to define the uppermost elevated position of the lip 66, as is best shown in FIG- URE 9.

The lip 66 is elevated from its normally gravity biased depending position shown in FIGURE 5 to its outwardly projecting position shown in FIGURE 1 by a snap line 72. The snap line is anchored at one end to bracket '73 mounted on the frame 22 and is connected at its other end to a rearward extension 78 of lever arm 74 which is pivotally mounted near its mid-point on pivot pin 75 to a bracket 76 mounted on the apron 70.

At its free end arm 74 has a roller wheel 77 which bears against the under surface of the lip 66 near its outer edge when the ramp is in lowered cross trafiic position, as is shown in FIGURE 5. 'In this position, the roller wheel 77 is remote from the piano hinge 67 and the moment arm of the lever 74 about hinge 67 is at its maximumv When the lip 66 is fully elevate-d, as is shown in FIGURE 1, roller 77 is proximate the hinge 67 and the moment arm of lever 74 therea'bout is at its minimum. Accordingly, the moment arm of lever 74 shortens progressively as the lip moves from depending to extending position.

The lip 66 is moved from its depending position to its extending position as the snap line becomes taut in the course of elevation of the ramp 25. Reference is made to FIGURE 5 where the ramp 25 is in its cross trafiic position with the lanyard 64 slack. The end of the lanyard is provided with a finger ring 80 which is'normally disposed below the level of the deck 26 in a recess 81 formed therein. The operator pulls the ring 81 to tension lanyard '64, thus releasing the overrunning latch 41. The springs 46 will then abruptly thrust upwardly against the ramp 25, this thrust being communicated through the elevator arms'31. When the ramp reaches an elevated position in which the snap line 72 becomes taut, some of the energy of the momentum of the ramp and the pressure of the springs is dissipated by translating it'into energy to fiip the lip 66 from its depending position shown in FIGURE 5 to its extending position shown in FIG- URE 1.

In the course of this movement of the lip between its respective positions shown in FIGURE 5 and FIGURE 1, arm 74is rotated'a'bout its pintle 75 and its point of application is shifted from near the edge of the lip remote from the piano hinge 67 to a point proximate the piano hinge 67 for smooth transmission of force to the lip, as aforesaid.

The lip 66 will be releasably held in its outwardly projecting position shown in FIGURE 1 by the lip latch mechanism best shown in FIGURES 9 through 16. Lip 66 is provided with a fixed arm 82 which is swingable in the course of lip movement through a slot 83 in the apron 70. At its end remote from the lip 66 fixed arm 82 is pivotally connected on pin 84 with bifurcated latch arm 58. Latch arm 85 has its otherwise free end a latch pad 86 which will seat against an abutment stop surface 87 of an abutment block 88 which is yieldably mounted on the under surface of the ramp deck 26, as best shown in FIGURES 9 through 16.

Block 88 is desirably shaped in the form shown in FIGURE 14. Behind its stop surface 87 it is relieved at 91 toform a cavity bounded on one side by wall 92 and on theother side by wall 93 which also functions as a guide tab or track for latch pad 86 as will hereinafter be described. Guide tab 93 extends forwardly of the stop surface 87, as indicated.

Abutment block 88 is embraced by way flanges 94 which are fixed to the under surface of the deck 26 by bolts 95. Behind the block 88 there is a ledge 96 also rigidly fastened to the deck 26 by the bolts 95. Ledge 96 has forwardly opening sockets 97 in which are seated compression springs 98 coiled about

pilot rods

99, 182 which project rearwardly from the abutment block 88. Pilot rod 102 is longitudinally extended through an opening 103 in the ledge and has its end threaded at 104 and provided with limit nuts 105 to limit the forward projection of the block 88 by the springs 98. Accordingly the block 88 is resistantly mounted to accommodate for impact shocks imposed thereon in the event a truck backs into the extended lip 66 at such time as the latch arm 85 is seated against the stop surface 87 of the block 88.

Latch arm 85 is biased by tension springs 106 toward the under surface of the deck 26. Springs 106 are connected at their upper ends on headed pins 107 to bracket arms 188 which are also rigidly mounted to the under surface of the deck 26 by the bolts 95. The lower ends of the springs 106 are connected to a cross pin 111 mounted on arm 112 connected to the latch arm 85. It is significant that the cross pin 111 has a smaller lateral extension at the side of arm- 112 nearest guide tab 93 than its lateral extension from the side of the arm 112 remote from the guide tab 93; and that the headed pins 107 are oppositely unequally offset from the arm 112. This is clearly shown in FIGURE 12 where the springs 106 incline downwardly and to the left in this view, as distinguished from being vertically disposed in this view. Accordingly the springs 106 have a component of bias to tend to urge the latch pad 86 to the right in FIGURE 12 and against the vertical wall of guide tab 93.

The deck 26 is provided with a hole 113 through which projects the button or foot pedal 114 by which the latch may be released by foot pressure. Button 114 is mounted on trigger means including arm 115 which is pivotally mounted on pin 116 which spans between the bracket arms 108. Trigger arm 115 has at its end remote from pivot 116 a latch arm release pad 117. When the button 114 is depressed by applying foot pressure thereto in the direction of arrow 120 in FIG. 11, the trigger 115'wil1 tilt to its position shown in FIGURE 11, thereby disengaging pad 86 on the latch arm 85 from the abutment stop edge 87, thus to release the latch mechanism.

If there is no external force holding the lip 66 against gravity descent, for example the truck bed 121 shown in FIGURE3, upon such release of the latch 85 its pad 86 will slide along the curved roof of the cavity 91 in the position shown inFIGURES 12 and 13 to their positionin FIGURES 15 and 16 in which pad 86 is in contact with the under surface of the guide tab 93. When foot pressure on the button 114 is released, springs 106 will return it to its position in which it projects through the opening .113. However, this will leave the latch arm and its pad 86 out of range of the stop surface 87 of the abutment block 88. Accordingly, if the truck 121 now moves away from the dock so that the lip 66 is no longer supported thereby, its gravity bias, will move it toward depending position and the latch arm 85 and its pad 86 will move rearwardly along the under surface of the guide tab 93 and to the position illustrated generally in FIGURE 5.

The operator has the option of depressing button 114 as soon as the lip has made contact with the truck bed,

. or he can wait until the truck has moved away before the latch button 114 is released. If the latch is released immediately, the latch arm will be shifted to its unlatched guide tab position, whereupon the lip will descend automatically when the truck leaves the dock. If the foot button is not depressed until after the truck leaves the dock, the lip will remain extended until the foot button is depressed, whereupon the lip will immediately descend to its depending position.

Incidental to movement of the lip 66 from its depending position shown in FIGURE 5 to its fully extended position shown in FIGURE 1, pad 86 will ride forwardly over the abutment block 88 and will be biased by springs 106 into cavity 91. This is indicated by the dotted line position of the pad 86 in FIGURE 16. Continued forwar-d movement of the pad 86 will result in its lateral engagement with the inclined side wall 122 of guide tab 93 so as to cam the pad 86 laterally towards its FIGURES 12 and 13 position where it will automatically engage the stop surface 87 when the lip is fully extended. The latch will accordingly automatically re-engage its stop abutment-surface 87 whenever the ramp is raised as illus-.

trated in FIGURE 1 to tighten snap line 72.

The frame 22 is provided along its front edge with an apron 123. Rearwardly thereof frame 22 is provided with support ledges 124 upon which the depending lip 62 will rest as shown in FIGURE 5 when the ramp is in its cross traffic position in which the deck 26 is at the same level as the surface 125 of the dock 20. In this position the foremost edge of the lip 62 is interlocked behind the upper margin or lip 126 of the apron 123. Under these circumstances, the closed overhead door 127 of the building blocks upward movement of the ramp 25, the engagement of the lip 66 with the ledges 124 prevents downward movement thereof and the apron lip 126 prevents outward movement of the lip 66, thus making the doorway burglarproof.

The snap line lever arm 74 is offset sideways from ledge 124, thus to permit the ramp to descend below cross traflic position if the lip 66 is extended, as shown in FIGURE 2.

The sequence of operation of the adjustable loading ramp herein disclosed is as follows: Assume that the ramp is in its FIGURE 5 initial position and that a truck is in the course of backing toward the station occupied by the ramp.

(1) Unless already open, overhead door 127 is first opened.

. (2) The operator pulls the lanyard 64 to release the ramp check mechanism 41. Springs 40 lift the ramp to its position shown in FIGURE 1. In the course of this movement snap line 72 will tighten to elevate the lip 66 and the latch arm 85 will engage the abutment block 88 to hold the lip 66 in its forwardly extending position.

(3) The operator will then walk out on the ramp 25 to lower it to its position where the lip will rest upon the bed of the truck 121. The truck bed may be above or below the level of the dock surface 125. FIGURE 2 illustrates the situation where the truck bed is below the dock level. In the course of this movement the overrunning latch mechanism 41 closes so that elevator arm 31 to which the latch mechanism 41 is attached will be locked in its lowermost position.

(4) If the truck is being loaded over the ramp so that truck springs compress, the truck bed 121 progressively lowers. The ramp 25 will follow the truck bed down and the overrunning latch 41 will further close.

(5) At any point in time after the lip 66 engages the truck bed, button 114 may be depressed to release the latch arm 85. Alternatively button 114 need not be depressed and the latch will remain engaged.

(6) After fully loaded, the truck can be driven away from the dock. If the latch button 114 has previously been released, lip 66 will automatically fall to depending position, as aforesaid. Otherwise, it will remain extended until the button 114 is actuated, whereupon the lip will then fall to depending position.

(7) To return the ramp to cross traffic position lanyard 64 is again pulled manually, thus to lift the ramp to FIG- URE 1 position. The operator walks out on the ramp and steps on the button 114 to drop the lip es to depending position and the board will come to rest in its cross trafiic position shown in FIGURE 5.

(8) If the truck is being unloaded instead of loaded, as in the step number (4) aforesaid, the truck springs will gradually expand during the course of unloading thereof. This is illustrated in FIGURE 3 where the truck bed 121 has risen from its FIGURE 2 position. The elevator arm 31 to which the latch 41 is connected is held by the latch in the same position which is occupied in FIGURE 2. However, the ramp 25 is free to move upwardly with the truck bed. Only the two springs 40 attached to immobilized arm 31 are held by the latch 41. The other set of springs 40 attached to the elevator arm 31 which is free of any connection to the latch 41 assist the board in rising with the truck bed. Return of the board to cross traffic position is eifectuated in the same way as described in connection with step number (7) aforesaid.

FIGURES 17 through 19 show a modified embodiment of ramp elevator. The rear standards 23 of the frame 22 are provided on their facing surfaces with vertically elongated

sockets

130, 139 which receive respectively the downturned ends 131, 138 of the allochiral torsion

bar elevator arms

132, 133. The opposite ends of

arms

132, 133 are respectively turned forwardly at 134, 135 to bear against the under surface of the ramp deck 25.

Sockets

130, 139 are unequally offset forwardly on their standards 23 to permit the

bars

132, 133 to pass without interference.

The torsion

bar elevator arms

132, 133 desirably consist of solid spring steel, prestressed to press upward against the ramp 25 when the bars are disposed in their stressed condition as shown in FIGURES 17 through 19.

The ends 134, 135 of the bars may bear directly against the under surface of the ramp, or

tubular extensions

136, 137 may be provided. Near their ends, the tubular extensions may be provided with adjusting bolts 140. By turning the bolts 140, the pressure of the torsion bars against the ramp may be adjusted.

The ramp check 41 may be connected by a pivot pin 141 to extension 137. In this manner, one of the torsion bars 132 is left in continuous pressure relation with the ramp but the other torsion bar 133 is subject to the ramp check 41.

The entire length of each torsion bar 132, .133 between their respective turned end portions is available for storage of energy. Accordingly, it is desirable that the

bars

132, 133 extend for the greatest possible distance. For this purpose, one end of each bar is adjacent one lateral side margin of the ramp deck 26 and its other end is adjacent the opposite side margin of the ramp deck. The torsion bar elevator arms shown in FIGURES 17 through 19 may substitute for the elevator arms shown in FIGURES 1 through 5 of the drawing, or may be used in any other loading ramp structure independently of any other feature of the apparatus herein disclosed.

The modified embodiments of the invention shown in FIGURES 20-3S contain features which may also be used independently of other features of the apparatus herein disclosed, or may be used together, as preferred. FIGURES 20-24 show a somewhat different connection of the respective ends 134, 135 of the

torsion bars

132, 133 of the FIGURES 17-19 embodiment to the undersurface of the ramp deck 25. As best shown in FIGURE 23, a pad 149 and block 150 are welded to the undersurface of the ramp deck in the vicinity of each

torsion bar end

134, 135. The block 150 is provided with sockets 151 to receive and confine the ends of adjustable bolts 152 which bear on the pad 149. The bolts 152 are threaded through respective ears 153 which have sockettubes 154 slipped over the respective ends 134, 135 of the

torsion bars

132, 133.

Accordingly, the ends of the torsion bars are securely anchored against shifting and the upward pressure of the torsion bars is transmitted to the deck 25 through the hearing pads 149 and keeps the ends of the bolts 152 seated in the block sockets 15 1. Bolts 152 are adjusted in the same manner as the bolt 14 of the embodiment shown in FIGURES 17-19.

FIGURES 20, 22 and 24 show how the deck may tilt with respect to its frame. The pivot pins 155, which pivotally connect the ramp 25 to the masts 23 of the frame 22, have a lost-motion connection with the ramp 25 in the direction of desired ramp tilt to enable it to accommodate to the slant of a canted truck bed 156, as shown in FIGURES 22 and 24.

For this purpose, the rear end of deck 25 is provided with brackets 157 which have elongated slots 158 in which the pivot pins 155 play. Normally, gravitys bias of the deck 25 will cause it to rest with the extreme top ends of the slots .158 in bearing contact with the pins 155. However, if the truck bed 156 has a lateral cant, the illustrated construction will permit the lip to conform thereto, when the weight on the ramp is near the lip. When this happens, the bracket 157 at the high side of the truck is free to tilt laterally, as shown in FIGURES 22 and 24. If the weight on the ramp is nearer to the end of the ramp pivoted to the frame, the ramp will tilt back to its level position. Accordingly, the materials handling truck which is moving over the ramp will always be able to transfer smoothly to and from the ramp, even though the truck bed itself is tilted. The slots 158 are desirably about four inches in length to accommodate tilts up to a four inch disparity in the level of the high and low sides of the truck bed. The slots 158 are elongated obliquely in the direction of desired tilt to require fore and aft shifting of the ramp during titlting thereof. This shifting, and the bearing pressure of pin 155 against the sides of slot 158, produces frictional resistance to tilting movement of the ramp. This means that the ramp is self-locked in any of its tilted positions, subject to displacement only if the displacement forces provided by the shifting weight on the ramp exceeds these friction forces.

The release button mechanism shown in FIGURES 20, 25, 26, 27, 28, 29, 33 and 34 is also specifically different from that shown in FIGURES 1-16, although it functions in the same general sequence as hereinbefore described. The button 161 is mounted on trigger means including arm 162 having downwardly extending side legs 163 which are pivotally connected to a pin 164 which spans between bracket plates 175 fixed to the under-surface of deck 25. The arm 162 and button 161 are biased towards their uppermost position in which the button projects upwardly through the hole 165 in the ramp deck 25 by a coil spring 166 which is wound around a pin 174 which spans between the plates 175. Corresponding free ends 167 of the coil spring 166 are in pressure engagement with pin 168 connected between the trigger arm legs 163. The opposite corresponding ends of the coil spring 166 are united in a loop 171 hooked around the abutment end 172 of a latch lever 173 which is pivotally inounted on the cross pin 174.

Cross pin 174 also serves as a pivotal support for the depending arms 176 of a box section slide bracket 177 through which freely slides one of the telescopic box section tubes 178 of the latch arm 181. The latch arm 181 has a second telescopic box section tube 182 connected on bracket 183 and pin 184 to the lever arm 185 of the lip 66.

While the latch arm 181 could be rigid, as is latch arm 85 of the previously described embodiment, latch arm 181 is desirably yieldable to absorb the pressure of a truck which may inadvertently back into the extended lip and thus relieve the ramp of shock.

For this purpose, the telescopically

related sections

178, 182 are provided with an internal compression spring 186 which is coaxial about a pilot rod 187. Rod 187 is fixed at one end 188 to end wall 191 of tube 182 and is free at its other end to slide through a bore filler block 192 which is welded internally to the tube 178. The fully extended position of latch arm 181 is defined by abutment of the adjustable nut 179 on stem 187 against block 192.

The top wall of tube 178 and the upper surface of the block 192 are cut into to form an abutment notch 193 into which the abutment end 172 of the lever arm 173 fits, as indicated in FIGURES 28 and 34, to latch the lip 66 in its extended position. Spring 186 has sufficient pressure to hold the lip 66 elevated, as shown in FIGURE 34. However, if a backing truck 194 inadvertently strikes the extended lip 66, spring 186 will yield to permit the lip gaging its finger end 198 from the catch-dog 195. This will move the latch lever 173 to its position shown in 70 at the front of the loading ramp 25 is provided with a swing lever 201 with a roller 202 adapted for shifting engagement with the undersurface of the lip 66. The swing arm 201 has a rearward extension 203 connected to snap line 204 anchored to the frame, as in the previously described embodiments.

The ramp check 200, shown in FIGURES 20, 22 and 30-32, differs somewhat from the ramp check 41 hereinbefore described. It consists of a cylinder member 205 which carries upright spaced plates 206 between which extends a slide strip 207 of brass. or the like. Pivotally mounted above slide strip 207 is a toothed pawl pad 208 carried on bracket arms 209 which are pivotally connected to the pin 210 which spans between the plates 206.

Between the pawl pad 208 and the slide strip 207 is a ratchet arm 212 having one end pivotally connectedon the pin 213 and bracket 214 to the undersurface of the ramp deck 25. The upper surface of ratchet arm 212 has teeth complementary to those on pawl pad 208.

Also spanning between the walls 206 are guide rollers 215 which guide the path of movement of the ratchet arm 212 with respect to the slide strip 207.

The angle of the coacting toothed surfaces of ratchet.

212 and pawl 208 is such as to permit the ratchet 212 to close, with respect to the pawl 208. However, the pawl to fold downwardly and rearwardly toward the loading ramp and against the stand-off lugs 190 on apron 70. FIGURE 28 shows in full and broken line representations the several successive positions of the backing truck and the ramp parts.

The undersurface of the foot button actuated trigger arm 162 is provided with catch means including catchdog 195 having a beveled forward surface 196 which coacts with a complementary surface 197 on the finger end 198 of lever 173 which is remote from its abutment end 172. Catch 195 functions to hold the latch abutment 172 away from engagement with the notch 193 when the button is depressed, as shown in FIGURE 26. When the button is depressed, the catch-dog 195 rides past the finger end 198 of the lever 173 to earn the lever 173 counterclockwise about its pivot 174, as shown in FIGURE 26, and against the bias of spring 166. This will withdraw the latch abutment 172 from the notch 193, thus permitting the lip 66 to drop if it is otherwise unsupported. In the fully depressed position of the button 161, the finger end 198 of lever 173 will snap or catch behind the catchdog 195 and the spring 166 will hold the parts thus engaged with the button 161 held down and the latch abutment 172 held up away from the notch 193.

Accordingly, with the parts in the position shown in FIGURE 26, the lip 66 is free to descend by gravity to its depending position, unless it is supported by the bed of the truck. When the truck completes its loading or unloading process and drives away, thus to remove support from the lip 66, the lip will promptly drop to its depending position. As a consequence of this movement, the latch arm 181 will be swung counterclockwise to its position shown in FIGURE 33, in the course of which the arm 181 will engage the end 172 of the lever 173 to cam it further in counterclockwise direct-ion, thus disen- The pawl 208 may be manually released from/the ratchet by lifting up on the release lever 216 which is guided for limited pivotal movement about pin 210 by the guide bracket 217 having a slot 218 in which the arm 216 is free to move.

The otherwise free end of the arm 216 is connected to a lanyard 221 which leads to a pull ring similar to that shown at in FIGURES 1 and 2 and which is recessed in a socket 81, also shown in FIGURES 1 and 2 of the drawing.

To take up unwanted slack in the lanyard, a tension spring 222 is desirably provided and yieldably connects the lanyard 221 near its midpoint with the frame 22.

The gravity bias of arm 216 is sufficient to maintain the pawl 208 against the ratchet 212 unless the arm 216 is lifted by tensioning the lanyard 221.

The cylinder 205 has a yieldable connection with the frame 22 through a stem 223 about which is wound a compression spring 224. The stem 223 is pivotally connected on pin 225 to a bracket 226 on the frame member 22. The opposite end of the stem 223 is provided with a shoulder 227 which receives the thrust of the spring 224, the other end of which bears against end wall 228 of the cylinder 205.

Low limit stop posts 231 are desirably provided on a front cross member 232 of the frame. Two such posts are provided, one near each'side of the ramp, as shown in FIGURE 24. Each consists of a base stem 233 having a series of lateral bore holes 234 at different heights. Telescopic on each is a tubular cap 235 having corresponding lateral bore holes 236 to receive adjusting pin 237 by which the height of the post 231 is readily adjusted.

The posts 231 are aligned vertically with the abutment apron 70 on deck 25 and will support the ramp deck in any desired low limit position within the range of adjustment of caps 235 with respect to stems 233. As shown in FIG. 20, abutment apron 70 is spaced from posts 231 when the ramp is in cross traflic position in which the depending lip 66 supports .the ramp on cross trafiic supports 238. Accordingly, if the lip is extended and if a truck inadvertently pulls away with a materials handling vehicle on the deck 25, the deck will be caught by the posts 231 to limit the drop of the deck. Where it is desired that the deck incline downwardly to reach a low truck bed, the posts 231 are adjusted to a lower position.

When the ramp is in cross traffic position, as shown in FIGURE 20, depending lip 66 is engaged behind lugs 238 which have the same function as lip 126 shown in FIGURE 5.

The operation of the loading ramp will ordinarily start from its cross traffic position, as shown in FIGURE 20. At the approach of a backing truck, the operator will pull the lanyard 221, thus releasing the ramp check 200 and permitting the

torsion bars

134, 135 to lift the ramp about its pivot pins 155. Before the ramp reaches its uppermost position, the snap line 204 will become taut, thus to elevate the lip 66, as her'einbefore described, and the roller 202 will shift its position along the undersurface of the lip between its position shown in FIG- URE ZOand its position shown in FIGURE 34. The latch arm 181- will accordingly be swung on its arm 185 to its position shown in FIGURE 34 where its notch 193 will come opposite the abutment lever 172 which will be biased by spring 166 into the notch, thus to latch the lip in elevated position, pending actuation of the button 161.

After the ramp is elevated, the operator will release the lanyard 221 so that the gravity bias on the arm 216 and the pawl 208 will engage the ramp check 200 so as to permit the ratchet arm 212 to ratchet over the teeth of the pawl and thus hold the ramp in any down position to which it is walked by the operator.

The operator will now walk out onto the ramp to add his weight to. the weight of the deck 25 and thus will lower the ramp until its lip 66 engages truck bed 121, as shown in FIGURE 25. This may further tilt the lip 66 upwardly about its hinge 67 to withdraw the latch abutment 172 from the notch 1%, as shown in FIGURE 25. However, until the button 161 is pressed downwardly, the spring 166 will maintain a downwardbias on the latch abutment 172 so that it will re-enter the notch 193 if the lip 66 drops toward depending position.

If the truck is being loaded over the ramp so that the springs of the truck compress and its bed drops to progressively lower levels, the weight of the deck 25 and the materials passing over the deck will cause the deck to follow the truck bed downwardly. The ramp check 200 will continue to ratchet in increments and hold the ramp in the down position.

On the other hand, if the truck is being unloaded so that its springs expand to lift upwardly on the ramp deck 25, the spring 224 in cylinder 205 will yield to permit the deck to follow the truck bed upwardly.

As before indicated, the operator may either step on the button 161 immediately to withdraw the latch abutment 172 to its position shown in FIGURE 26, or he may wait to do this until the loading or unloading operation is completed. If the button is depressed prior to withdrawal of the truck from beneath the lip 66, the lip will drop to depending position as soon as the truck departs. If the operator does not step on the button 161 until after the truck withdraws, the lip 66 will be held extended by the latch mechanism, and the operator will then have to step on the button to return it to depending position.

After the truck leaves, the ramp may be restored to its cross trafiic position by again pulling on the lanyard to raise the deck, walking the deck down and stepping on the button to drop the lip, which will engage behind the lugs 238.

What is claimed is:

1. An adjustable loading ramp comprising:

(a) a frame,

(b) a ramp pivotally connected at one end to the frame for swinging in a vertical plane,

(c) a lip pivotally-connected to the other end of the ramp,

(d) means for'swinging the lip from a depending position to an outwardly extending position,

(e) latch means for holding the lip in said outwardly extending position,

(f) and manual release means for said latch means comprising:

( 1) a foot actuated push button mounted at a foot accessible position on said ramp,

(2) and trigger means interconnecting said button with said latch means,

(g) said latch means further comprising:

' (1) an abutment on the undersurface of the ramp,

(2) a latch arm on the lip,

(h) said trigger means being responsive to push button actuation for shifting the relative positions of the latch arm and the abutment to move the same out of range of each other.

2. The loading ramp of claim 1 in Which said latch means further comprises a guide tab laterally adjacent said abutment, said means for shifting the relative positions of the latch arm and abutment comprising spring means biasing the latch arm laterally toward said tab.

3. The loading ramp of claim 1 in which said abutment comprises a lever, a pivot pin on which the lever can turn, biasing means urging the lever around said pin toward abutment with the latch arm, said lever being within range of movement of the trigger means to move it against the bias of said spring means and out of range of the latch arm.

4. The loading ramp of claim 3 in which the trigger means is further provided with releasable catch means for said lever for releasably holding the lever out of range of the latch arm after the trigger means is actuated.

5. The loading ramp of claim 4 in which said lever and latch arm have cam and cam-follower portions by which said catch means is released on movement of the latch arm to reset the button.

6. The loading ramp of claim 5 in which said biasing means comprises means to bias said trigger means to reset position on release of said catch means.

7. In a device of the character described including a ramp, a lip pivotally connected to the end of the ramp, and latch means for holding the lip in an extended position from which gravity biases the lip toward a depending position, said latch comprising:

(a) a latch arm on the lip,

(b) an abutment block on the under surface of the ramp,

(c) said abutment block having an abutment stop and a guide tab laterally adjacent said stop,

(d) said ramp having a hole,

(e) a latch release button mounted in said hole and having a trigger engageable with the latch arm,

(f) spring means biasing said latch arm laterally toward said guide tab for movement of said latch arm from said stop to said guide tab When the push button is actuated,

(g) said guide tab having a laterally inclined side surface to return said latch arm to-said stop against the bias of said spring means.

8. An adjustable loading ramp comprising a frame, a ramp pivotally connected to the frame for swinging in a vertical plane, elevator means for the ramp comprising first and second torsion bars, said bars having first end portions bearing on the frame, second end portions bearing on the ramp and intermediate tension portions connecting said end portions, the said portions of the bars being disposed in allochiral relationship; said frame being provided at its end proximate the end of the ramp pivotally connected thereto with laterally spaced stand- 13 ards near the lateral margins of the ramp and having reaction means against which said first ends of said bars bear, the second end portions of each bar being disposed near the opposite lateral margin of the ramp from their respective first end portions.

9. A loading ramp comprising:

(a) a frame,

(b). a ramp pivotally connected at one end to the fram for swinging in a vertical plane,

(d) means pivotally connecting the lip to the other end of the ramp,

(e) latch mechanism for selectively holding the lip extended from the ramp and permitting it to depend therefrom, said latch mechanism comprising:

(1) a yieldable latch arm having one end in motion transmitting connection to the lip,

(2) releasable locking mechanism at the other end of the latch arm to selectively lock the latch arm to the ramp and release the arm from the ramp,

(3) said latch arm being yieldable under pressure against said lip to permit the lip to swing about said pivot means and retract toward its depending position even when the latch is locked.

10. The loading ramp of claim 9 in which the latch arm comprises telescopically related parts and spring means therebetween fornormally biasing the parts to extended position.

11. In a loading ramp having a frame, a ramp platform hinged .to the frame at its rear end, and an elevator for pivoting the platform about its hinged rear end to lift the platform to an upwardly inclined elevated position, the improvement in said elevator comprising direct thrust transmitting allochiral torsion bar elevator arms respectively having intermediate portions extending transversely of the platform near its rear end, corresponding opposite ends of the arms being turned transversely of their intermediate portions and respectively in thrust bearing engagement with the frame and platform, said arms constituting continuous stressed torsion links directly transmitting lift pressure between the frame and platform.

12. The loading ramp of claim 11 in which the thrust bearing between corresponding ends of the arms and one of the frame and platform comprises adjusting screws, whereby to adjust the torsion of the arms.

13. A loading ramp comprising: a frame, a ramp pivotally connected at one end to said frame,

an elevator to swing the ramp about the frame,

an apron at the other end of the ramp and extending transversely thereacross,

a lip pivotally connected to the apron,

means to move the lip from a depending position in which it extends along said apron to an outwardly extending position in which it constitutes an extension of said ramp,

said apron having a downward extension less than the lip when the lip is in its depending position,

cross traflic support means on the frame on which said lip bears in its depending position,

fixed position low limit stop means on the frame in vertical alignment with the apron to support the ramp independently of said cross traffic support means when the lip is in a position. other than its depending position, said low limit stop means being spaced from the apron when the lip is in its depending position bearing on said cross traflic support means,

an adjusting means to adjust the support level of said low limit stop means.

14. The device of claim 13 in which said low limit stop means comprises posts having telescopically related parts, said adjusting means comprising means to hold said parts in one or another of several telescopically related positions.

References Cited by the Examiner UNITED STATES PATENTS 2,714,735 8/1955 Watson 14-71 2,751,615 6/1956 Kelley 14-71 2,797,434 7/ 1957 Vigmostad 296-76 X 2,846,703 8/1958 Adley 14-71 2,871,505 2/1959 Clark 296-76 X 2,974,336 3/1961 Kelley 14-71 3,061,855 11/1962 Layne 14-71 3,087,178 4/1963 Loomis 14-71 3,117,332 2/1964 Kelley 14-71 3,137,017 6/1964 Pfleger 41-71 JACOB L. NACKENOFF, Primary Examiner.

Claims

1. AN ADJUSTABLE LOADING RAMP COMPRISING: (A) A FRAME, (B) A RAMP PIVOTALLY CONNECTED AT ONE END TO THE FRAME FOR SWINGING IN A VERTICAL PLANE, (C) A LIP PIVOTALLY CONNECTED TO THE OTHER END OF THE RAMP, (D) MEANS FOR SWINGING THE LIP FROMA DEPENDING POSITION TO AN OUTWARDLY EXTENDING POSITION, (E) LATCH MEANS FOR HOLDING THE LIP IN SAID OUTWARDLY EXTENDING POSITION, (F) AND MANUAL RELEASE MEANS FOR SAID LATCH MEANS COMPRISING: (1) A FOOT ACTUATED PUSH BUTTON MOUNTED AT A FOOT ACCESSIBLE POSITION ON SAID RAMP, (2) AND TRIGGER MEANS INTERCONNECTING SAID BUTTON WITH SAID LATCH MEANS, (G) SAID LATCH MEANS FURTHER COMPRISING: (1) AN ABUTMENT ON THE UNDERSURFACE OF THE RAMP, (2) A LATCH ARM ON THE LIP, (H) SAID TRIGGER MEANS BEING RESPONSIVE TO PUSH BUTTON ACTUATION FOR SHIFTING THE RELATIVE POSITIONS OF THE LATCH ARM AND THE ABUTMENT TO MOVE THE SAME OUT OF RANGE OF EACH OTHER.