US3223267A - Lift truck - Google Patents

Description

Dec. 14, 1965 H. A. STAMMEN 3,223,267

LIFT TRUCK Filed Sept. 30, 1964 3 Sheets-Sheet 1 JIE. I

INVENTOR. 21420.10 17. 5 MMME/V H/S 4 770 PNEY'S Dec. 14, 1965 A. STAMMEN LIFT TRUCK 5 Sheets-Sheet 2 Filed Sept. 30, 1964 BY W17 Dec. 14, 1965 H. A. STAMMEN 3,223,267

LIFT TRUCK Filed Sept. 50, 1964 5 Sheets-Sheet 5 1 IIIIIIIIIIIII I; \u2 T INVENTOR. l-l/JEOLD Al. STflHMf/V BY WM;

United States Patent U 3,223,267 LEFT TRUCK Haroid A. Stammen, New Bremen, Ghio, assignor to Qrown Controls (Zorporation, New Bremen, Ohio, a corporation of Ohio Filed Sept. 30, 1964, Ser. No. 434L463 Claims. (Ci. 214-739) This invention relates to a lift truck and more particularly to a fork lift truck having pivoted tines. The invention is illustrated herein as adapted to engage and raise baskets of tobacco leaves. It will be understood, however, that the invention is not so limited.

An object of this invention is to provide a fork lift truck having pivoted tines of simple and rugged construction.

A further object of this invention is to provide mechanism for automatically pivoting the fork tines upon initial actuation of power means adopted to raise the tines.

Another object of this invention is to provide a latch mechanism preventing upward movement of the tines until the tines are moved to a predetermined minimum separation one from the other.

Other objects and advantages reside in the construction of parts, the combination thereof, the method of manufacture and the mode of operation, as will become more apparent from the following description.

Referring to the drawings:

FIGURE 1 is a perspective view of a lift truck made in accordance with this invention as viewed from the front of the truck.

FIGURE 2 is a perspective view of the truck of FIG- URE l, as viewed from the front and to one side of the truck.

FIGURE 3 is a perspective view similar to FIGURE 1, but showing parts in different positions.

FIGURE 4 is a cross sectional view of a portion of the lift truck as viewed in the direction of arrows 4-4 of FIGURE 3.

FTGURE- 5 is an enlarged elevational view of a portion of the lift truck enclosed within the circle 55 of FIG- URE l and illustrating a latch mechanism.

Referring to the drawings in greater detail, a lift truck made in accordance with this invention is generally designated 8 and includes a base It) upon which is mounted a housing 12 for the drive and steering mechanisms. These mechanisms may be entirely conventional and, hence, are not illustrated herein. The lift truck 8 illustrated in the drawings is intended to employ an electric drive and lift motor (not shown) powered by batteries (not shown) enclosed within battery housings 14 located on opposite sides of the housing 12. Projecting forwardly of the battery housings 14 are elongate, parallel outrigger arms 16 having small wheels 18 at the forward ends thereof. The wheels 13 are used in association with caster wheels and a large drive wheel (not shown) located immediately benath the housing 12 and generally centrally thereof to support the entire lift truck. Movement of the truck along the floor is controlled by an operator who stands on a platform 2i provided with a backrest 22 in convenient position to control a steering handle 24 connected by a steering column 26 to the steering mechanism located within the housing 12. Other suitable control members, such as a hydraulic control lever 28, are located on the top panel of the housing 12.

The forward end of the base 19 is recessed to provide a central base platform ii. A hydraulic lift cylinder 30 is supported centrally of the platform 11 upon a support plate 29. The lift cylinder 30 drives a piston 32 having a T-shaped cross head 31 upwardly when fluid is supplied to the cylinder 39 through conduits such as that indicated at 33. At the outer ends of the cross head 31 are sprocket wheels 34 engaged by lift chains 36. Each of the chains 36 has one end fixed to the base 10 in any siutable fashion and its other end attached, as by a U-shaped fixture 38 (FIGURE 4) to a rod 46 threadedly engaged in an aperture in a mounting plate 4-1 affixed to a bracket 42, which will be described in greater detail below. Except for the brackets 42, the entire assembly thus far described may be entirely conventional. As will be appreciated from the ensuing description, initial upward movement of the piston 32 upon actuation of the cylinder 30 will cause the ends of the chains 36 connected to the brackets 42 to rise. In accordance with this invention, further upward movement of the piston 32 will cause an entire load engaging or fork lift assembly, generally designated 44, to

rise.

The load engaging assembly 44 comprises a carriage 46 and a tine assembly including the brackets 42 and tines 62 connected thereto. The carriage 46 consists of a horizontal top plate 58, a pair of tine support plates 43 depending from the rear edge of the top plate 48, a horizontal lower plate 50, vertical side braces 51 and a vertical center braces 52. The braces 51 and 52 are welded or otherwise afiixed to the rear edges or surfaces of plates 58, 48 and 50 interconnecting them. Guide rollers 54 mounted on the center braces 52 behind the plates 48 and 50 are engaged with the opposed internal faces of a pair of channel members 56 which are mounted on the base platform 11 immediately forwardly of the housing 12 and on opposite sides of the lift cylinder 30. stiffening plates 57 interconnect the channel members 56. As well known to those skilled in the art, the guide rollers 54 moving within the channels 56 provide for vertical travel of the load engaging assembly 44. The previously mentioned tine support brackets 42 are pivoted upon pivot pins 60 which are supported by the plates 48 and spacer plates 63, there being one pivot pin 60 supported by each pair of plates 48 and 63.

As may be readily observed from the drawings, each bracket 42 is generally L-sh'aped, having an upper horizontal extension 42a to which the chains 36 are connected and a vertical extension 421). One tine 62 is connected to the lower end of the vertical extension 42b of each bracket 42. The tines 62 project forwardly or outwardly from the brackets 42 in generally parallel relationship to the outrigger arms 16. Referring to FIGURE 1, the tines 62 are normally held in spaced apart relation by pairs of coil springs 64, each connected at one end to fingers 66 which are in turn attached to the horizontal extensions 42a of the brackets 42 and at their other ends to pins 68 affixed to the lower plate 50 by a bracket 70. The coil springs draw the horizontal extensions 42a downwardly against stop plates welded between the bottom edges of the support plates 48 and vertical bracket guide plates 67, extending in front of the brackets 42. While two pairs of coil springs 64 are illustrated in FIGURE 1, it will be apparent to those skilled in the art that only a single coil spring 6 would be necessary and, in fact, other biasing devices such as a pneumatic cylinder could be used in place thereof.

Also shown in FIGURE 1 is a basket or tray 72 of the type commonly used to support a pile of tobacco leaves. The tines 62 are wedge or chisel shaped for the purpose of sliding partially underneath the upwardly turned ends of the basket 72. Also, the leading and inner edges 62a of the tines 62 slope rearwardly to avoid damage to the baskets 72 as the tines 62 advance toward the basket 72.

The operation of the device as thus far described is as follows. Upon initial upward movement of the piston 32, the brackets 42 are pivoted about the pivot pins 66 against the bias of the springs 64, so as to draw the inner ends of the horizontal extension 42a upwardly, whereupon the tines 62 are pivoted one toward the other, thereby wedging or camrning underneath the basket or tray 7 2. This movement of the tines 62 continues until the upper surfaces of the brackets 42 engage the lower surfaces of a pair of stop screws 74 threaded through apertures in the top plate 58. Following this initial movement of the cylinder 30, the tines 62 are in generally parallel relationship but remain adjacent floor level between the outrigger arms 16, as illustrated in FIGURE 2. Because the upper edges of the brackets 42 are engaged with the lower surfaces of the stop screws 74, continued upward movement of the piston 32 causes the lift assembly 44 to rise into that position shown in FIGURE 3.

The load is lowered by returning the piston 32 downwardly into the cylinder 30. During lowering, the weight of the load and the carriage 46 maintains the springs 64 taut and the upper surfaces of the brackets 42 remain engaged with the stop screws 74. Subsequently, the carriage 46 lowers to a fixed stop created by engagement of the bottom edges of the braces 52 with the base platform 11. Because the load is thereafter elfectively supported by the base platform 11, the springs 64 return to their original position as shown in FIGURE 1 while the piston 32 continues to lower.

The afore described apparatus is ideally suited for use in tobacco warehouses. Several hundred pounds of tobacco leaves may be loaded on baskets such as that illustrated at 72. The tobacco leaves overhang the edges of the basket. Therefore, the operator cannot see the pickup points. By straddling the basket, however, and moving the forked tines 62 symmetrically toward one another near floor level, the basket can easily be engaged for pickup. It will be appreciated that the hydraulic control system for the cylinder 32 can be entirely conventional and need not be different from any other control system used merely to raise the piston 32. Thus, separate controls for moving the tines 62 relative to one another are unnecessary. A single control button, which may be located on the steering handle 24, used to actuate the hydraulic pump which supplies fluid to the cylinder 32 is all that is required to first pivot the tines 62 one toward the other, subsequently raise the tines 62 above floor level, return the tines 62 to floor level and separate the tines.

The top of the stack of tobacco leaves in basket 72 may be engaged by a stabilizer assembly comprising a pair of spaced generally L-shaped arms 80, the upper ends of which are connected by three stiffening braces 82 and which overlie the tobacco leaves. The vertical portions of the arms 80 are adapted to slide in sleeves 84 attached to opposite sides of the housing 12. The vertical height of the arms 80 can be adjusted by removal and reinsertion of lock pins 86 which pass through apertures in the upper ends of the sleeves 8 and through apertures 88 in the arms 80. I

For some uses it may be desirable or even essential that a predetermined minimum separation of the tines 62 is reached prior to the raising of the lift assembly 44. To this end, a latch assembly, shown best in FIGURE 5, may be provided for preventing vertical upward movement of the lift assembly 44 relative to the base 10. The latch assembly may include a latch bar 92 mounted for horizontal sliding movement on a bracket 92 supported by the base 10. A coil spring 94 having one end attached to a pin 96 affixed to the bracket 92 and its other end affixed to a pin 98 connected to the latch bar 90 biases the latch bar to the right, as viewed in FIGURE 5, toward the adjacent brace 52. A latch roller 100 is attached to the brace 52 as by a bracket 102 and rolls upon a pin 194 which passes through the bracket 102 and an aperture in the lower plate 50. See FIGURE 3 in addition to FIG- URE 5. When the parts are in the position shown in full lines in FIGURE 5, which is the same as that shown in FIGURE 1, and the tines 62 positioned as shown in FIGURE 1, upward movement of the lift assembly 44 is prevented, since the lower edge of the latch bar 9% prevents the latch roller 1% from moving upwardly. The usual hydraulic overload protection system or by-pass circuit associated with the lift cylinder 39 will go into operation should further movement of the tines 62 toward one another be prevented. If the tines 62 are pivoted toward one another, however, a lug or plate 106 connected to the rear face of the vertical extension 42b of the bracket 42 engages the end face of a latch release bar 108 which passes through a sleeve 110 and has an enlarged end section 112 abutting against the face of the latch bar 92 closest to the brace 52. As apparent from an inspection of FIGURE 5, movement of the tine 62 illustrated therein to the left causes the release bar 198 to be moved to the left; consequently, the latch bar is also moved to the left whereby vertical upward movement of the latch roller 3% to the position indicated by phantom lines a is permitted. A light spring a housed within the sleeve I10 biases the release bar 198 to the right during vertical travel of the lift assembly 44. As the lift assembly 44 is lowered so as to return the tine 62 to adjacent ground level, the roller 1% first engages a sloping end surface of the latch bar 9%, thus camming it against the bias of the spring 94 whereupon the latch roller 1% returns to its initial position beneath the latch bar 90 illustrated in FIG- URE 5. The enlarged end 112 of the release bar 108 engages the end face of the latch bar 90 before the roller I60 becames disengaged therefrom, and it also returns to the full line position shown in FIGURE 5. Thus, it may be seen that the latch mechanism is automatically reset as the lift assembly 44 lowers to return the tines 62 to ground level. Subsequent upward movement of the lift assembly 44 is prevented until the bracket 42 is returned to a position such as that indicated by the phantom lines 420 in FIGURE 5. The latch assembly illustrated in FIGURE 5 is shown in connection with the bracket 42 and tine 62 on the right side of the lift truck as viewed in FIGURE 3. If desired, an identical latch assembly responsive to the position of the tine 62 on the left side as viewed in FIGURE 3 could also be mounted on the base platform 11 and carriage 46.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion .and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. In a lift truck, the combination comprising: a base, a carriage mounted for vertical movement relative to said base, a pair of brackets mounted on said carriage for pivotal movement about generally parallel, horizontal axes, a pair of load engaging tines, one connected to each bracket and movable therewith, power operated lift means mounted on said base and connected to said brackets pivoting said brackets about said axes, and a stop surface fixed relative to said carriage preventing pivotal movement of said tines and said brackets beyond a predetermined position, said tines pivoting about said axes upon initial operation of said lift means and said carriage raising upon continued operation of said lift means.

2. The combination of claim ll, further including a slidable latch bar mounted on said base, a latch element mounted on said carriage, bias means normally positioning said latch bar in overlying relationship to said latch element whereby upward movement of said carriage is prevented, a latch release means engaged with said latch bar responsive to pivotal movement of one of said tines and moving said latch bar away from overlying relationship to said latch element when said one of said tines is pivoted to a predetermined position.

3. In a lift truck, the combination comprising: a base, a carriage mounted for vertical movement relative to said base, a pair of load engaging tine assemblies pivotally connected to said carriage, releasable latch means interconnecting said carriage and said base normally preventing vertical travel of said carriage, and latch rel-ease means operatively engaged by one of said tine assemblies during pivotal movement thereof to release said latch means.

4. In a lift truck of the type having a vertically driven lift piston, a fork lift assembly comprising; a carriage mounted for vertical movement on said truck, a pair of tine assemblies mounted for pivotal movement on said carriage, stop means on said carriage engaged by said tine assemblies in a predetermined position of said tine assemblies, and bias means connected to said carriage and said tine assemblies biasing said tine assemblies away from said stop means, said tine assemblies being connected to said driven lift piston and pivoting against said bias means upon upward movement of said piston into engagement with said stop means.

5. In a lift truck of the type having a vertically driven lift piston, a folk lift assembly including: a carriage mounted for vertical movement on said truck, a time assembly mounted for pivotal movement on said carriage and connected to said lift piston, stop means on said carriage engaged by said tine assembly in a predetermined pivotal position thereof, and bias means connected to said tine assembly biasing said assembly away from said stop means, upward movement of said lift piston pivoting said tine assembly toward said stop means against said stop means and raising said carriage after said tine assembly engages said step means.

No references cited.

HUGO 0. SCHULZ, Primary Examiner.

Claims (1)

1. IN A LIFT TRUCK, THE COMBINATION COMPRISING: A BASE A CARRIAGE MOUNTED FOR VERTICAL MOVEMENT REALTIVE TO SAID BASE, A PAIR OF BRACKETS MOUNTED ON SAID CARRIAGE FOR PIVOTAL MOVEMENT ABOUT GENERALLY PARALLEL, HORIZONTAL AXES, A PAIR OF LOAD ENGAGING TINES, ONE CONNECTED TO EACH BRACKET AND MOVABLE THEREWITH, POWER OPERATED LIFT MEANS MOUNTED ON SAID BASE AND CONNECTED TO SAID BRACKETS PIVOTING SAID BRACKETS ABOUT SAID AXES, AND A STOP SURFACE FIXED RELATIVE TO SAID CARRIAGE PREVENTING PIVOTAL MOVEMENT

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