US3589541A

US3589541A - Load handling in forklift trucks

Info

Publication number: US3589541A
Application number: US801137A
Authority: US
Inventors: Thomas N Melin
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-02-20
Filing date: 1969-02-20
Publication date: 1971-06-29
Anticipated expiration: 1988-06-29

Abstract

A slope-piling arrangement for a forklift truck in which one of the lifting forks has its vertical leg movably engaged with the fork apron so that the fork leg, during movement relative to the apron, is constrained to move vertically, and in which a power drive mechanism is connected between the apron and the fork for moving the fork relative to the apron.

Description

United States Patent Inventor Thomas N. Melin 1424 24th Ave., Longview, Wash. 98632 Appl. No 801,137 Filed Feb. 20, 1969 Patented June 29, 1971 Continuation-impart of application Ser. No. 439,846, Mar. 15, 1965, now Patent No. 3,429,470.

LOAD HANDLING 1N FORKLIFT TRUCKS 4 Claims, 10 Drawing Figs.

US. Cl 214/731, 214/750, 214/1 Int. Cl B661 9/12 FieldolSe-rch 214/730, 731, 750, 702

Primary ExaminerGerald M. F orlenza Assistant Examiner-Robert J. Spar Attorney-Christie, Parker & Hale References Cited UNITED STATES PATENTS Jannsen Skutle et al.

Lull Erickson et al.

Drakulich Gibson et al Houseman et a1.

214/750 214/731 214/731 X 214/660 214/731 X 214/731 X 214/731 ABSTRACT: A slope-piling arrangement for a forklift truck in which one of the lifting forks has its vertical leg movably engaged with the fork apron so that the fork leg, during movement relative to the apron, is constrained to move vertically, and in which a power drive mechanism is connected between the apron and the fork for moving the fork relative to the apron.

LOAD HANDLING IN FORKLIFT TRUCKS CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of copending application Ser. No. 439,846 filed Mar. 15, 1965 and issued Feb. 25, 1969 as US. Pat. No. 3,429,470.

FIELD OF THE INVENTION This invention relates to forklift trucks. More particularly, it relates to apparatus adjustably interconnecting the lifting forks of forklift trucks with the fork apron so that a load car ried on the forks may be lifted from or deposited on loadreceiving means angled out of the horizontal with respect to the truck chassis.

BACKGROUND OF THE INVENTION In load handling with forklift trucks, the load is supported on a pair of forks which extend forwardly from a vertically movable apron mounted to the front end of the vehicle. Usually the load is lifted from or deposited on a foundation or the like defining a load-receiving plane parallel to the surface which supports the truck. Often, however, the surface upon which the load is to be deposited, or from which the load is to be lifted, is not parallel to the floor or other surface which supports the truck. In such cases, the forks cannot be engaged with load without damaging the load and/or the truck, or the load cannot be deposited without damage to the truck, to the load, or to the load-receiving structure.

This invention provides simple, effective and economic apparatus which adjustably interconnects at least one of the forks of a forklift truck to the fork apron for vertical movement of the fork relative to the apron and relative to the other fork. Existing trucks can be modified to receive this apparatus. Moreover, the apparatus can be incorporated readily into the design of a truck during manufacture of the truck. The apparatus has the feature that its use does not increase the off set of the truck, thereby assuring that the load-handling capacity of the truck is essentially undiminished. The offset of a forklift truck is the distance between the center of the front axle of the truck and the front surface of the fork apron. Such apparatus is referred to herein as a slope-piling apparatus. As used in this specification and in the appended claims, the term slope-piling apparatus" refers to apparatus by which a forklift truck is capable of lifting a load from, or depositing a load on, a surface which is angled, in a direction only transversely of the truck, relative to a surface on which the truck is disposed.

SUMMARY OF THE INVENTION Generally speaking, this invention provides a slope-piling apparatus for a forklift truck. The forklift truck for which the slope-piling apparatus is provided includes a chassis, a fork apron mounted for controlled vertical movement relative to the chassis, and a pair of load-bearing fork members extending from the fork apron. The slope-piling apparatus comprises means mounting one of the fork members for guided movement vertically of the fork apron, and controllable means operatively coupled between the fork apron and the one fork member for moving the one fork member vertically relative to the fork apron and the other fork.

DESCRIPTION OF THE DRAWINGS The above-mentioned and other features of the invention are more fully set forth in the following detailed description of the invention presented in conjunction with the accompanying drawings, wherein:

FIG. 1 is a front elevation view of the fork apron of a forklift truck equipped with apparatus according to this invention;

FIG. 2 is a side elevation view of the structure shown in FIG.

FIG. 3 is a fragmentary front elevation view of another apparatus according to this invention and which is claimed in the above-referenced patent;

FIG. 4i is a fragmentary front elevation view, with parts broken away, of still another apparatus according to this invention;

FIG. 5 is a fragmentary side elevation view of another slopepiling device according to the invention;

FIG. 6 is a rear elevation view taken along line 6-6 in FIG.

FIG. 7 is a side elevation view of still another slope-piling arrangement;

FIG. 8 is a side elevation view of yet another slope-piling apparatus;

FIG. 9 is a rear elevation view taken along line 9-9 in FIG. 8; and

FIG. 10 is a fragmentary front elevation view of still another slope-piling apparatus.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS FIGS. l and 2 show a fork apron 10 mounted for vertical movement to an elevator 11 which is connected to the front end of the chassis 12 of a forklift truck 13. The elevator typically includes two pairs of channel members 14, I5. Outer channels 15 are pivoted to the truck chassis by pins 16, and inner channels 114 have their upper ends connected together by a bridge (not shown) and are mounted to channels 15 by rollers (not shown) for vertical movement relative to the outer channels. A hydraulic ram 117 is also connected to the chassis at its lower end and is connected to the bridge at its upper end. A length of chain 18 is connected at one end to the fork apron and passes over a pulley (not shown) mounted to the bridge. The other end of the chain is fixed relative to the chassis. The fork apron carries rollers 19 which are engaged between the flanges of the inner channels to mount the apron to the elevator. As ram 17 is extended, the apron is moved vertically an amount double the extension of the ram. The truck chassis is supported on ground 20 by wheels 21. The details of the elevator and its drive mechanism are not part of this invention which resides in the structure mounting the forks (described below) to the fork apron.

Fork apron 10 includes upper and

lower crossmembers

22 and 23, respectively, side members 24, and vertical intermediate members 25. A pair of

fork members

26, 27 are carried by the fork apron. Fork member 26 has a vertical leg 28 and a horizontal leg 29, the latter leg being the fork tine upon which a load is engaged when the truck is in use. Fork member 26 is secured to the fork apron by a horizontal hanger rod 30 mounted to apron upper member 22 and passed through a hole 311 in the upper end of the vertical leg of the fork member. Fork member 26, therefore, is not movable vertically relative to the fork apron. The rear surface of the fork member bears against the front face of the apron lower member.

A conventional forklift truck usually has two fork members generally like those described above, both of which normally are secured to a fork apron in the same manner that fork member 26 is secured to apron 10, or in an equivalent manner. Those skilled in the art, however, will readily appreciate that the manner in which fork member 26 is connected to apron is not a part of this invention, and is described above merely for the purpose of a complete explanation of the invention.

Fork member 27, however, is mounted to the fork apron for movement vertically relative to the apron. This fork member has a vertical leg 32 and a horizontal leg or tine 33 like fork member 26. The upper rear portion of vertical leg 32 defines a boss 34 through which is formed a vertically elongated slot 35 extending parallel to the front surface of the leg. Hanger bar 30 passes through the slot and cooperates with the slot to guide the fork member in vertical movement relative to the apron.

The slope-piling apparatus also includes means for moving fork member 27 vertically relative to the fork apron. A hydraulic ram assembly 36 has one end pivotally connected to lower apron member 23 and its other end disposed between and pivotally connected to a pair of lugs 37 secured to the rear side of vertical fork member leg 32 adjacent the lower end of boss 34. The ram preferably is a double-acting ram and is operated by hydraulic fluid supplied to the ram assembly through ducts 38 and 39. The nature of fluid flow through the ducts is controlled by the operator of the truck, thereby controlling the operation of the ram. It will be readily apparent to those skilled in the art that mechanisms different from that described, for example, ajackscrew, may be used to move the fork member vertically relative to the fork apron.

FIG. 3 illustrates another form which structure according to this invention may take. A fork member 40 has a vertical leg 41 and a horizontal leg or load-bearing tine (not shown). The upper rear portion of the vertical leg defines a boss (not shown in FIG. 3 but similar to boss 34 shown in FIG. 2 as a part of fork member 27) through which extends a vertically elongated slot 42. The slot traverses the boss parallel to the front surface of the fork member vertical leg. A horizontal hanger bar 43 extends through slot 42 and has its ends supported in a pair of vertical members 44 in a fork apron 45. The fork apron also includes an upper transverse member 46 to which vertical members 44 are connected. The upper transverse member of the fork apron has an aperture 47 formed through it above the fork member. The aperture is large enough to permit the upper end of the fork member vertical leg to be moved through it. Aperture 47, slot 42 and hanger bar 43 cooperate with each other to guide the fork member in vertical movement relative to the fork apron.

An elongated vertical notch 48 is formed in the upper end of fork member vertical leg 41 and extends from front to back of the leg. A hydraulic ram assembly 49 is disposed in the notch and has one end secured to the fork member. The other end of the ram assembly is secured to a sleeve 50 which journals the hanger bar in notch 48. The ram is operated to move the fork member upwardly and downwardly relative to apron 45. Motive fluid is supplied to the ram assembly through ducts (not shown) which connect the ram assembly to a suitable control at the truck operator's station.

FIG. 4 shows yet another structural arrangement of slope piling apparatus according to this invention. Fork apron 52 includes a transverse upper member 53, a pair of vertical members 54 secured to the upper member, and a crossmember 55 disposed below the upper member and extending between and secured to the vertical members. A fork member 56 has a vertical leg 57 and a horizontal leg or tine (not shown). The upper end of the fork member vertical leg has a hole 58 formed through it from side to side of the leg parallel to the forward surface of the leg. The hole is horizontal and receives a hanger rod 59, the ends of which extend laterally of the fork member. The ends of the hanger rod are slidably received in respective ones of a pair of vertically elongated slots 60 formed through the apron vertical members adjacent the apron upper member. The hanger rod and slots 60 cooperate to guide the fork member in vertical movement relative to the fork apron.

A hydraulic ram assembly 61 is coupled between the fork apron and the hanger rod. One end of the ram assembly, preferably cylinder 62, is secured to apron crossmember 55. The other end of the ram assembly, preferably the outer end of piston 63, is connected to a yoke member 64 which extends from adjacent one side of the fork member vertical leg around behind the leg to the other side of the fork member as shown in FIG. 4. The ends of the yoke member are secured to respective ones of a pair of sleeves 65 which journal hanger rod 59 between the fork member and apron vertical members 54. Operation of the ram assembly is produced by hydraulic fluid supplied to the ram assembly through supply ducts 66 and 67 at the control of the operator of the truck.

Preferably the apron crossmember defines therein a forwardly opening notch 68 which has a width slightly greater than the width of the fork member vertical leg. Notch 68 provides a further guide mechanism for the fork member as it is moved vertically relative to the fork apron in response to controlled operation of ram assembly 61.

FIGS. 5-10 illustrate other embodiments of slope-piling mechanisms according to this invention. FIGS. 5 and 6 show a fork apron 70 to which one fork member 71 is mounted for vertical movement relative to a second fork member (not shown) which may be mounted to the apron in any manner desired, such as the manner in which fork member 26 is mounted to apron l0. Fork member 71 has a load supporting horizontal leg 72 and a vertical leg 73 which is movably engaged for guided movement in a vertical passage 74 defined by the apron. In the vicinity of the movable fork member, the apron has a front plate 75, a backplate 76 and laterally spaced

spacer plates

77 and 78, the latter extending vertically of the apron between the frontand backplates. Plates -78 define the boundaries of passage 74 which has a cross-sectional configuration conforming to that of the vertical leg of the fork member and which is sized to loosely receive and yet adequately guide the vertical leg. A power drive mechanism 79 is coupled directly between the apron and the fork member for moving the fork member vertically relative to the apron; the capacity of the drive mechanism is sufficient to move the fork member even when the movable fork member cooperates with the other fork member to support a load up to and equal to the rated load capacity of the forklift truck of which apron 70 is a component. As shown in FIGS. 5 and 6, the drive mechanism preferably is a double-acting hydraulic ram 80 pivotally connected between a lug 81 secured to the rear surface of backplate 76 and a lug 82 secured to the rear of the vertical leg of the fork member adjacent the junction between the vertical and horizontal legs of the fork member. The ram is connected to the hydraulic control system of the forklift truck by suitable

hydraulic lines

83 and 84 so that, upon actuation of the ram in the appropriate direction, the fork member is driven in guided movement relative to the apron. To maximize the guiding engagement of the apron with fork member leg 73 and also to maximize the range through which the fork member may be moved relative to the apron, a downwardly open slot 85 is formed in the lower edge of back plate 76 centrally between

spacer plates

77 and 78 to accommodate lug 82.

FIG. 7 is a side elevation view of a slope-piling arrangement which is similar to that shown in FIGS. 5 and 6, but in which apron does not define an enclosing passage for the vertical leg 91 of a fork member 92 which also has a load-supporting horizontal leg 93. Apron 90 includes a pair of spacer plates 94 and 95 which are arranged similar to

spacer plates

77 and 78 of apron 70; the front and rear edges of the spacer plates lie forwardly and rearwardly, respectively, of the corresponding surfaces of the fork member vertical leg, as shown. A front keeper bar 96 is connected between spacer plates 94 and 95 adjacent the upper extent of the apron to slidably engage and constrain the front surface of the fork member vertical leg. A rear keeper bar 97 is connected between the spacer plates adjacent the lower extent of the apron to slidably engage and constrain the rear surface of fork leg 91. Plates 94 and 95 and

keeper bars

96 and 97 define an open passage along which the vertical leg is guided when a drive mechanism, such as a double-acting hydraulic ram 98 having

supply lines

99 and 100, is operated. Ram 98 is connected between a lug 101 secured to the upper rear extent of the vertical leg and a lug 102 secured to the rear surface of rear keeper bar 97. The capacity of ram 98 should be as described concerning ram 80.

It will be apparent that, regardless of whether a load is supported by the horizontal leg of fork member 92, the fork member, by reason of its own weight and geometry, engages the front and rear keeper bars in the manner indicated by the arrows in FIG. 7. Thus, the described structure is effective to both support and guide the fork member during use of the forklift truck of which the apron is a component. it will also be seen that ram 98'is connected between the apron and the movable fork member in such manner to maintain and even augment proper engagement of the fork member with the keeper bars.

The embodiment shown in FIGS. 8 and 9 includes front and rear keeper bars 105 and 106 which are secured to the front and rear surfaces of the vertical leg 107 of a fork member 108 having a horizontal load-supporting leg 1109. Vertical leg 107 cooperates within a vertical passage lllll formed within apron 110 which has a backplate 112 having a rear surface substantially coplanar with the rear surface of the vertical leg; the apron has a front plate (not shown), the front surface of which is substantially coplanar with the front surface of vertical leg 107 on opposite sides of the passage. The keeper bars extend laterally in opposite directions of the sides of the fork member vertical leg to slidably engage the exterior surfaces of the apron frontand backplates and to transfer the loads of and applied to the fork member to the apron. A double-acting hydraulic ram 1M, comprising power drive means for the slope-piling mechanism shown in FIG. 9, is connected between lugs 115 secured to the lower rear extent of vertical leg 107 and a bar 116 which extends parallel to the backplate and is supported on opposite sides of the passage by lugs 117 secured to the backplate. Ram ll 14 is connected to the forklift truck hydraulic system by suitable hydraulic lines lllltl and 119. Upon application of a load W (FIG. 9) to the fork member, the keeper bars are forcibly engaged with the apron as shown by the arrows in FIG. 9. The embodiment shown in FIGS. 8 and 9 operates according to much the same set of principles as are applicable to the operation of the embodimerits shown in FIGS. 57.

The embodiments described above and shown in FIGS. l- 9 involve, in basic terms, structure in which only one of two load-handling fork members is vertically movable relative to a supporting elevatable apron; it will be appreciated, however, that both forks may be movable vertically relative to the apron without departing from the scope of the invention. The embodiment shown in FIG. provides two vertically movable forks which are interconnected to move simultaneously equal amounts in opposite directions upon operation of the power drive mechanism associated with the forks.

Thus, as shown in FIG. 10, a pair of lifting

fork members

125 and 126, each having a vertical leg 127 and a horizontal leg 128, are associated with an elevatable fork apron 129 in a forklift truck, such as truck 13. The forks are disposed forwardly of an apron front plate 130 and are located adjacent the left and right ends of the apron as viewed in FIG. 10. Each fork is engaged with a separate hanger bar 1131 and 132 in the manner described above relative to fork 26. The hanger bars are supported at their juxtaposed ends in corresponding ones of a pair of support blocks 133 and 134 secured to the apron front plate. The bars cooperate in oversized holes 135 formed through the blocks. The adjacent ends of the bars define rounded heads 136 which may abut each other as shown in FIG. 10.

The opposite ends of each of the hanger bars, outwardly of the corresponding fork member, carry a roller 13.8 which is engaged with a bearing plate 139 secured to the apron, preferably in the adjacent upper corner of the apron. A suspension link 140 is associated with each hanger bar and has its lower end connected to the bar, preferably between the corresponding fork member and the corresponding roller. The other end of each suspension link is pivotally connected to a corresponding bellcrank 1412, the bellcranks being spaced from each other along the length of the apron and pivotally mounted to the apron at 143 and 1%, respectively. The bellcranks are pivotally interconnected by a connecting rod 145.

A drive mechanism Mi", such as a double-acting hydraulic .am 148 having suitable

hydraulic lines

149 and 150 connecting it to the hydraulic system of the forklift truck, is connected between one of the bellcranks and the apron for driving the forks upwardly and downwardly relative to the apron. Operation of the drive mechanism, because of the arrangement of the bellcranks as shown in FIG. 10, causes forks and 126 to move equally in opposite directions relative to the apron, thereby to controllably adjust the angular relation of a load supported on the forks relative to the apron about an axis normal to the apron front plate. During such movement of the forks, the hanger bars pivot relative to the apron about pivot points 151, and the rollers roll along bearing plates 139.

The utility of slope-piling apparatus according to this invention is apparent from the following description of the operation of the embodiment shown in FIGS. 1 and 2. Let it be assumed that the forklift truck is supported on a horizontal surface such as ground 20, and that fork member 27 is positioned so that its horizontal leg is disposed in the same horizontal plane as the horizontal leg of fork member 26. This is the usual position of the vertically movable fork member. Let it also be assumed that the operator of the truck desires to engage the fork tines under a pallet upon which a load is supported so that the loaded pallet can be lifted and moved by the truck, but that the pallet is resting on a surface which is inclined to the horizontal across the truck at an angle A (see FIG. 1 which is of such magnitude that both forks cannot be engaged under or within the pallet. If the truck were moved forward in an attempt to engage the forks with the pallet, one or the other or both the fork members would engage the pallet structure, the load on the pallet, or the structure upon which the pallet is supported; such engagement of the forks with any of these things would damage the structure so engaged and might damage the truck itself. To avoid this result, the operator of the truck merely operates ram 36 to raise or lower the movable fork member an amount sufficient to locate both fork members in a plane parallel .to the surface on which the pallet is supported; vertical correspondence of these planes can be achieved by raising or lowering the fork apron. The forks can then be engaged with the pallet with ease, and the pallet can then be lifted and placed in a horizontal condition by returning the movable fork member to its normal position.

If a load supported on the fork members is to be deposited on a surface which is inclined across the truck relative to the surface on which the truck is supported, the process described above can be reversed. It is preferred that the forks be placed in a plane parallel to the surface upon which the load is to be deposited before the apron is lowered so that the weight of the load will be uniformly distributed over the receiving structure as the load is deposited. If a conventional forklift truck having forks fixed vertically relative to the fork apron were used in the situation described, the forks could not be withdrawn from under the load without damage to the load, to the load receiving structure, or to the forks.

As indicated above, the vertically movable fork member in slope-piling apparatus according to this invention normally is positioned at the midpoint of its range of vertical movement relative to the fork apron; the structure for moving and for guiding the movable fork member is arranged so that the tine of the movable fork member is then disposed in the same horizontal plane as the tine of the other fork member, assuming the truck itself is horizontal. Such a normal position of the movable fork member enables the fork to be moved either up or down as required. This normal position of the movable fork member also means that only a single movable fork is required to provide a truck capable of lifting or depositing loads on surfaces inclined either way across the truck relative to the surface on which the truck itself is located. Obviously, however, as shown in FIG. 10, the truck could be provided with two vertically movable forks, which forks may or may not be operatively interconnected as shown in FIG. 10.

The invention has been described above in the context of specific types of mechanisms and structural arrangements. Workers skilled in the art to which the invention relates will recognize that modifications and alterations may be made in the mechanisms and structures described without departing from the spirit of the invention. Accordingly, the foregoing description is not to be considered as limiting the scope of this invention.

What I claim is:

l. Slope-piling apparatus for a forklift truck having a fork apron extending transversely of the length of the truck and a pair of load-bearing forks carried by the apron and extending forwardly of the chassis from the apron in spaced relation to each other, each of the forks having a vertical leg and a horizontal leg, the slope-piling apparatus comprising means mounting the vertical legs of the forks to the apron for guided movement vertically relative to each other including a substantially horizontal elongate hanger bar for each fork aligned substantially perpendicular to the fork horizontal legs and fixed to the upper end of the vertical leg of the corresponding fork adjacent the end of the bar opposite from the other fork, means pivotally mounting the other end of each bar to the apron, linkage means coupled between the hanger bars remote from said pivotally mounting means arranged to cause one fork to move vertically relative to the apron in response to vertical movement of the other fork relative to the apron an equal amount in the opposite direction, and controllable power means connected between the apron and the linkage means for moving the linkage means in such manner as to move the hanger bars equally and to move the forks equally vertically in opposite directions relative to the apron.

2. Slope-piling apparatus for a forklift truck having a fork apron extending transversely of the length of the truck and a pair of load bearing forks carried by the apron and extending forwardly of the chassis from the apron in spaced relation to each other, at least one of the forks having a vertical leg which is movable relative to the apron, the slope-piling apparatus comprising means mounting the vertical leg of the one fork to the apron for guided movement vertically relative to the other fork including a substantially horizontal elongate hanger bar for the one fork connected at one end thereof to the upper end of the vertical leg of the one fork, means pivotally mounting the other end of the hanger bar to the apron at a location on the apron between the forks, linkage means coupled to the hanger bar remote from said pivotally mounting means arranged to cause the one fork to move vertically relative to the apron, and controllable power means connected between the apron and the linkage means for moving the linkage means in such manner as to pivotally move the hanger bar to move the one fork vertically in relation to the apron and to the other fork.

3. Slope-piling apparatus for a forklift truck having a fork apron extending transversely of the length of the truck and a pair of load-bearing forks carried by the apron and extending forwardly of the chassis from the apron in spaced relation to each other, each of the forks having a vertical leg and a horizontal leg, the slope-piling apparatus comprising means mounting the vertical legs of the forks to the apron for guided movement vertically relative to each other including substantially horizontal elongate hanger bar means for the forks aligned transversely of the apron substantially perpendicular to the fork horizontal legs and at its opposite ends to the upper end of the vertical leg of the corresponding fork, means pivotally mounting the hanger bar means to the apron between the fork vertical legs, linkage means coupled to the hanger bar means remote from said pivotally mounting means arranged to cause the forks to move vertically relative to the apron in opposite directions, and controllable power means connected between the apron and the linkage means for moving the linkage means to move the forks vertically in opposite directions relative to the apron.

4. Slope-piling apparatus for a forklift truck having a fork apron extending transversely of the length of the truck and a pair of load-bearing forks carried by the apron and extending forwardly of the chassis from the apron in spaced relation to each other, at least one of the forks having a vertical leg which is movable relative to the apron, the slope-piling apparatus comprising means mounting the vertical leg of the one fork to the apron for guided movement vertically relative to the other fork, linkage means coupled to the vertical leg of the one fork and operable to move the one fork vertically relative to the apron, and controllable linear motion power means disposed at the top of the apron with the line of action thereof oriented substantially horizontal and connected between the apron and the linkage means for operating the linkage means to move the one fork vertically relative to the apron and to the other fork.

Claims

1. Slope-piling apparatus for a forklift truck having a fork apron extending transversely of the length of the truck and a pair of load-bearing forks carried by the apron and extending forwardly of the chassis from the apron in spaced relation to each other, each of the forks having a vertical leg and a horizontal leg, the slope-piling apparatus comprising means mounting the vertical legs of the forks to the apron for guided movement vertically relative to each other including a substantially horizontal elongate hanger bar for each fork aligned substantially perpendicular to the fork horizontal legs and fixed to the upper end of the vertical leg of the corresponding fork adjacent the end of the bar opposite from the other fork, means pivotally mounting the other end of each bar to the apron, linkage means coupled between the hanger bars remote from said pivotally mounting means arranged to cause one fork to move vertically relative to the apron in response to vertical movement of the other fork relative to the apron an equal amount in the opposite direction, and controllable power means connected between the apron and the linkage means for moving the linkage means in such manner as to move the hanger bars equally and to move the forks equally vertically in opposite directions relative to the apron.