US2254331A

US2254331A - Lift truck

Info

Publication number: US2254331A
Application number: US379553A
Authority: US
Inventors: Jr William Stuebing
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-02-19
Filing date: 1941-02-19
Publication date: 1941-09-02
Anticipated expiration: 1958-09-02

Description

Sept. 2, 1941. w. STUEBING. JR 2,254,331

LIFT TRUCK Filed Feb. 19, 1941 5 ShGGtS-Shet 1 I. a g O WW) 1))" .-v 5*, 3" INVENTO ATTORNEYS Sept. 2, 1941. w. STUEBING. JR

LIFT TRUCK Filed Feb. 19, 1941 5 Sheets-Sheet 2 INVENTOR William 511101)!) ATTOR EYS p 2, w. STUEBING. JR 2,254,331

LIFT TRUCK 1 Filed Feb. 19, 1941 5 Sheets-Sheet 3 LIFT TRUCK 5 Sheets-Sheet 4 WLllLam BY 1 m,

Sept. 2, 1941- V w. sfussms. JR

Filed Feb. 19. 1941 F. f MP Sept. 2, 1941.

W. $TU EBING. J R

LIFT TRUCK 5 Sheets-Sheet 5 Filed Feb. 19, 1941 i l I I I I l I ll Patented Sept. 2, 1941 STATE LIFT UCK

9 Claims.

This invention relates to lift trucks and more particularly to hand operated lift trucks where the lifting operation is performed by swinging the steering handle, and the truck is propelled in order to move the load by a motor drive on the truck which motor drive is controlled by push buttons on theend of the steering handle.

. An object of this invention is to provide a manually operated mechanism which may be used, for example, for lifting movable platforms of the type where a quantity of material is piled on the platform and the loaded platform is then moved. A further object is to provide an efficient and dependable means for lifting a load and for moving the load. A still further object is to provide means for manually lifting a load and for then moving the load by means of a motor drive. A still further object is to provide a mechanism of the above character which is sturdy in construction and efficient in operation, and which is light in weight and economical to manufacture. A further object is to provide a mechanism which may be used with perfect safety under a wide variety of conditions. Other objects will be in part out hereinafter.

The invention accordingly consists in the features of construction, combination of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described and obvious and in part pointed the scope of the application of which will be indi- I cated in the followingclaims.

In the drawings in which one embodiment of the invention is disclosed:

Figure l is a perspective view of a lift truck;

Figure 2 is a schematic showing of the motor control circuit;

Figure 3 is a side elevation partly in section and with the central portion of the frame broken away;

Figure 4 is a sectional Figure 6;

Figure 5 is similar to Figure 4 but shows certain parts of the apparatus at a different stage in the cycle of operations;

Figure 6 is a top plan view of the forward end of the truck with certain parts broken away for clarity;

Figure 7 is a perspective view of the mechanism shown in Figure 6; and

Figure 8 is a vertical sectional view of the mounting for the rear wheels of the lift truck, showing the gears which transmit motive power from the drive shaft to the rear axle.

view on the line 22 of Serial No. 317,069, filed February 3, 1940, entitled "Lift truck and issued December 10, 1940, as Patent No. 2,224,166, and to my copending application, Serial No. 370,090, filed December 14,

1940, entitled "Lift truck, and material shown a lifting frame which may be moved to and from a raised position, in which position it supports the load. Mounted on the lower frame is an electric motor which is connected through gears to the the rear wheels, and this motor is operated to drive the truck. Power is derived from a set of storage batteries upon the forward end of the truck. The truck is provided at its forward end with a steering handle, and the motor is controlled by means of switches on.the free end of the steering handle. Thus, the operator may, stand at the end of the handle and operate a switch to back the truck beneath the load, such as a movable platform upon which is piled the material to be lifted and moved.

' With the lifting frame beneath the platform, the lifting frame is raised by swinging the steering handle through a vertical arc with the result that the load is lifted and fully supported by the lift truck. The operator then operates the proper switch to propel the load either forward or backward as desired, and during the movement he steers the truck by swinging the steering handie in the usual manner. Thus, during the lifting and load-moving operations, the operator manipulates only the steering handle and the control switches at the end of the steering handle. When the load is carried to the new location, the lifting frame is lowered, releasing the load.

In the present embodiment the lifting frame is raised by means of a hydraulic ram which is operated by swinging the steering handle, there being a releasable mechanical connection between the steering handle and the hydraulic ram. The hydraulic ram is of such a character that it acts as an automatic latching means to hold the lifting frame in partially or fully elevated position, and it also acts as a check to retard the descent of the lifting frame. This embodiment is also provided with safety means which prevents the operator from elevating the lifting This application is related to my application, 5 frame beyond a certain predetermined limit.

Furthermore, when a load is elevated and the operator wishes to release it, it is desirable that he be free to attend to the truck and to guide the load as it settles. According y. with the present embodiment, the load is automatically latched in partially or fully raised position, and when the release treadle is actuated, the hydraulic ram is rendered ineffective except as a check until the lifting frame and the load have fully descended from the elevated position. Thus, the operator need only actuate the treadle. and he is then free to give his attention to the control of the load and the truck.

Referring particularly to Figure 1 of the drawings, a chassis is provided which is formed mainly by a lower'frame 2, a pair of rear wheels 4, and a pair of front wheels 8. This chassis carries the operating mechanism for lifting the load and the motor for driving the truck. The lower side of the motor housing is shown in Figure 1 to the left of the rear wheels, and the motor is designated generally at H. At the forward end of the truck is a storage battery housing 200, which encloses a set of storage batteries 20! (see also Figure 2) for supplying power to motor ll. Housing 200 is built integrally with the forward end of the lower frame or chassis construction (Figure l), and on the front wall of the battery housing is a controller box 202 which contains relay switches, etc., controlling the supplying of power to .the motor. The control of the motor will be explained in detail below in connection with the discussion of Figure 2, which is a schematic representation of the driving mechanism.

The chassis assembly, including the wheel mountings and the lifting mechanism, will be explained below, but it is of the type shown in my copending application referred to above. The front wheels 8 are mounted on an axle I which is carried'by a fork l2 attached to the lower end of a king bolt I4. King bolt l4 extends through a cross-head l6 which forms the forward end of the lower frame 2. Mounted on the top of king bolt I4 is a forked bracket 42 which carries a pivot pin 44 extending between the two arms of the bracket. Pivot pin 44 carries a cylindrical steering-handle sleeve 46 having two ears at its lower end which are pierced by and pivot on the pivot pin 44, there being one ear adjacent each of the two arms of bracket 42.- The cylindrical body portion of steering-handle sleeve 46 snugly receives the lower end of the steering handle 40 with a limited sliding movement between the steering handle and the steering-handle sleeve.

The upper or free end of the steering handle is provided with a T-connection 204 which carries a cross-pipe 206, the two ends of which form the hand grips which are held by the hands of the operator when the truck is being used. Mounted at the left side of the T-connection 204 so that it is on the lower side of the handle when the handle is in the horizontal position, is a switch box 208 which is provided on its top face with two push buttons 2l0 and 2l2.

Push buttons M0 and 2 l2 are operated to control the driving of the lift truck; that is, when push button H2 is depressed, power is delivered to motor H to drive the truck forward; and when push button H0 is depressed, the motor is driven in the opposite direction so that the truck is driven to the rear. In this embodiment, the push! buttons control double switches so that when one push button is pressed, the circuit to the other push button is opened.

Push buttons U0 and 2l2 are shown schematically at the left of Figure 2, with armatures 2H and 2l3, respectively, which are held in the position shown by springs. When in this position, armature 2 of switch 2l0 bridges a pair of contacts 2 and H8, and armature 2l3 bridges a pair of similar contacts 2 I8 and 220.

Contacts 2i

4 and 220 are connected to a power line 222, which extends to the control box 202, and contacts H8 and M8 are connected, respectively, by jumpers 223 and 225 to a pair of

contacts

228 and 224. When push button 2| 0 is pushed inwardly, its armature 2 is moved (downwardly in Figure 2) to bridge contact 224 and a cooperating contact 228, and similarly. when push button M2 is pushed inwardly, its armature H3 is moved to bridge contact 228 and a cooperating contact 230.

Contacts

228 and 230 are connected, respectively, by

lines

232 and 234 to the relay mechanism in the control box 202.

Lines

222, 232 and 234 are in the form of a single cable 236 which extends from the switch box 208 (Figure 1) within the steering handle 40 and out through an opening in the side of the steering handle sleeve 48, and thence to the control box 202. The mechanism within the control box is connected to the set of storage batteries 20l (Figure 2) by a pair of

lines

238 and 240, and four

lines

2, 242, 243, and 244 extend from the control box to the motor ll. The proper voltage is supplied through these four lines to run the motor II in the proper direction and at the desired speed to drive the lift truck. Power is transmitted from the motor to one of the rear wheels through a gear assembly shown in Figure 8 and to be more fully described below. The speed at which the lift truck is to move is regulated, depending upon the conditions under which the truck is to be used, by changing the motor speed and the gears of this gear assembly.

When power line 222 is connected to line 232 by the depressing of push button 2 l0, circuits are completed through control box 202 to drive motor H and move the truck forward, and when power line 222 is connected to line 234 by the depressing of push button 212, motor I I is driven in the opposite direction so that the truck is moved to the rear. However, the only manner in which line 232 may be connected to power line 222 is through contact 228, armature 2| I, contact 224, jumper 225, contact 218, armature 213 and contact 220, and if push button M2 is not bridging contacts H8 and 220, this circuit is not completed. Thus, with the push buttons positioned as shown, the depressing of push button 2 l 0 completes the circuit between line 232 and power line 222. and the truck is moved to the rear; but if push button H2 is depressed while push button 2|0 is in its depressed position, armature 2l3 is held away from contacts 2l8 and 220, and the circuit is broken so that no power is delivered to the motor. In a like manner, line 234 is connected to power line 222 through contact 230, armature 2l3, contact 226, jumper 223, contact 2l6, armature 2H and contact 2H and this circuit is completed only when push button 2l0 is in the position shown and push button 2| 2 is depressed. Thus, if only push button H2 is depressed, the circuit will be completed to drive the truck forward, but if push button H0 is depressed while push button M2 is in its depressed position, armature 2 will not bridge contacts 2 and 2l6, and the circuit will not be completed.

It will thus be seen that if accidentally both push buttons are depressed simultaneously, the truck will not move, and if the truck is moving due to the depressing of one button, thedepressing of the other button will disconnect the power and the truck will stop. This is an important safety feature not only in protecting the power circuits and the control mechanism, but also in acting to disconnect themotor under some circumstances during operation. Illustratively, if the operator is moving the truck for- Ward, and he suddenly stops so that the end of the steering handle pushes against him, both push buttons will be depressed and the motor will be shut off. Furthermore, if the operator is confused, it is important that the truck remain at rest, and it has been found that byproviding this type of control, the operator will give careful consideration to his action before attempting to move the truck.

The positioning of the push buttons in the manner shown, has additional advantages in that the operator maintains firm control of the hand grips of the steering handle, and at the same time he manipulates the push buttons with ease to drive the truck as desired. The push buttons are so positioned that the operator normally tends to place himself for most efficient action at all times. When the steering handle 40 is swung to its horizontal position, the operator will normally grasp the handle with only one hand, and with the control buttons positioned as shown, the thumb is used to operate the proper button. Illustratively, if the truck is to be moved forward, the operator will grasp the handle with one hand, and will face the direction of truck movement, with the thumb naturally positioned over the push buttons 2) and 2I2. When the truck is to be moved to the rear, the operator will face the truck and normally grasp the handle with both hands, and his thumbs are automatically positioned over the push buttons.

The steering handle is normally held near the horizontal position so that the push buttons are at the level of the operators hands, and when in this position, the steering is performed easily and the operator is held away from the truck so that he does not ride the truck. The speed of the truck is adjusted to be that at which the operator can easily walk, but if for any reason the truck should tend to run faster than he cares to walk, he can momentarily release the push button so that the truck coasts. .This makes it possible for an untrained operator to operate the truck without undue strain, and it has been found that the operator remains efficient and alert. If the operator should drop the steering handle accidently, push buttons 2m and 2I2 would be released and the truck would stop. The truck need not be designed to carry the extra weight of the operator as the operator always walks, and this has the added advantage that the motor, the gearing and the batteries are all of reduced size and weight. Furthermore, there is an added factor of safety in providing that all of the operations be carried on at the end of the steering handle where the operator is free to move about.

In this embodiment the truck is driven through the left rear wheel (shown at the right of Figures 1, 2 and 8) through a gear assembly which is shown diagrammatically in Figure 2 and more in detail in Figure 8. Motor II has its shaft 246 connected through a coupling 2% to a drive shaft 25d which extends through a ball bearing assembly 25| into a grease-tight gear box 251. At the extreme end of the drive shaft and upon the ends of the axle are the two rear.

wheels 4. The rear wheel 4 at the right is keyed to the axle and thus the gear assembly provides a direct mechanical connection between the wheel and the motor II.

In this embodiment sufficient traction is obtained to drive the truck by one wheel, but when desirable, a differential may be provided, and the .truck may be driven from both of the rear wheels. As indicated above, the motor may be energized intermittently to keep the truck running at a rate slower than normal, and when it is desirable to stop the truck quickly, the motor is energized to tend to rotate in the opposite direction, and the motor then tends to act as a generator-brake. When the motor is not operating, the truck may be moved manually in either direction.

As indicated above, the lifting structure is of the type shown in my copending application, and this structure is shown best in Figures 3 to '7. Referring particularly to the left-hand side of Figure 3, the lower frame 2 is provided at the rear with reinforcing brace structure U which carries a shaft 32, and at the forward end with a frame construction, generally indicated at 2I,

which acts as a reinforcing means and which also supports the mechanism for elevating the lifting frame 22. The lifting frame 22 is formed by a U-shaped side member 24 extending along the sides and the rear of the truck, a rear brace structure 26 and a saddle-like front cross-frame 28. At the rear the lifting frame is provided with a pair of link pivots 33 which are carried by the rear brace structure 26, and a pair of links 36 pivotally connect these link pivots to shaft 32 with the links being respectively positioned at or near the ends of the shaft.

At the front of the frame construction 2i (see Figure 6) of the lower frame 2 are two supporting sleeves I03, and these sleeves carry a lifting axle I02 which supports a pair of lifting arms I04 and I06, best shown in Figure 7. Lifting arm I 04 is shaped as best shown in Figures 4 and 5 with one end receiving a pivotal axis I08 which is rigidly carried by cross-frame 28 and with the other end .of the lifting arm carrying a pivot IIIl. Referring to Figure '7, lifting arm I06 has one end connected to a pivotal axis H2 rigidly carried by cross-frame 28, and the other end of lifting arm I06 carries a pivot H4 (see Figure 6). Pivot H0 carries a thrust bar IIG (Figure '7), and pivot H4 carries a similar thrust bar I I8, and these thrust bars extend rearwardly where they are pivotally connected to the opposite ends of a U-shaped yoke I20. Yoke I20 is slidably mounted, and at its center it is mechanically connected to the plunger I 22 of the hydraulic ram I 24.

The hydraulic ram I24 is provided with a shell I26, and within this shell is a mechanism of known character which is in the nature of-a hydraulic ram and check which contains a light oil, and (see Figure 3) which has at the right.

a pumping plunger rod I28 and a releasing rod I30. When the pumping plunger rod I28 is moved from right to left into cylinder I26, oil within the cylinder is pumped through a valve at the center of the cylinder into an inner chamber (not shown) with the result that plunger I22 is forced to the left out of the cylinder. This moves yoke I20 to the left and pulls thrust bars H6 and H8 (see Figure 6) to the left, and this swings lifting arms I04 and I06 about lifting axle I02 with the result that the lifting frame is elevated.

Reverting to Figure 3, at the rear of the truck the pivots of links 36 are spaced apart the same distance as the distance between lifting axle I02 and pivotal axles I08 and I I2 so that the entire lifting frame rises with a steady arcuate movement. The lifting frame is raised by a number of individual pumping strokes of the pumping plunger rod I28, and at the end of each of the pumping strokes, the ram automatically holds the lifting frame in the partially raised position. When it is desirable to release the load, releasing rod I30 is pulled to the right (Figure 3) against the force of a spring (not shown) and this permits the oil to escape from the chamber at the left of the ram, but the escape is restricted, and the movement of the load downwardly is thereby checked. Referring to Figure 6, at the side of each of the thrust bars H6 and I I8 is a ten-' sion spring I32 which springs tend to move the yoke I20 and the lifting bars to the right to insure a smooth operation of the mechanism and to prevent lost motion.

Referring to Figure 3, the pumping plunger rod I28 is operated by the swinging of the steering handle 40. As indicated above, the steering handle has its lower end slidably received in the steering handle sleeve 46, and the steering-handle sleeve has two ears which are pierced by the pivot pin 44 which is carried by the two arms of the forked bracket 42. At each side the bottom of the steering-handle sleeve 46 is provided with a slot 48, and extending into these slots are the two ends of the pin 50 which is rigidly carried by the lower end of steering handle40. The steering handle 40 is held in the sleeve by pin 50, and due to the fact that the slots 48 are elongated, there may be limited longitudinal sliding movement of the handle with respect to the sleeve, but the steering handle is otherwise rigidly held within the sleeve. The steering handle is balanced by a compression spring 84 which extends between a bracket 92 on sleeve 46 and pivot 88 on bracket 42. Extending through the spring to hold the spring in alignment is a rod 90 pivoted at its lower end on pivot 88.

Mounted upon the center of pivot pin 44 between the ears of steering-handle sleeve 46 is a segment hook 52 which is provided with a disc segment 54, having an arcuate surface 55, and a hook portion 56. On the base of the hook portion is a bumper 58 which limits the counterclockwise movement of the segment hook. Hook 56 is engaged with the eye 60 of a lifting link 62, the lower portion of which is formed by U-bolt 64, rigidly secured by .nuts 65. The lower end of U-bolt 64 is looped into one eye of a double-eye link 68, the other eye of which is pierced by a pivot pin I0, carried by a double-armed pumping lever 69 which is mounted upon the center of the lifting axle I02. The lower arm of pumping lever 60 is connected through a pair of links II to the pumping plunger rod I28 of the hydraulic ram, there being a pivot pin I3 connecting the pumpinglever to links II and a pivot pin I2I connecting links II to rod I28. The various elements of the linkage assembly tend to return to the position shown by virtue of a tension spring I which is connected to the top of the cross-head I8 and at the other end to pumping lever 68.

The lower end of steering handle 40 is reinforced by a plug and is provided with a latch por- I .II to move pumping plunger rod I28 to the left,

and this causes plunger I22 to move a short distance from cylinder I26. This acts in the man-- ner indicated above to start the elevation of the lifting frame. The steering handle 40 is then swung upwardly and during this movement spring I 29 draws the elements back to their respective positions as shown in Figure 3, except that plunger I22 remains extended and the lifting frame is partially elevated. The steering handle is then swung downwardly again and the operation is continued until the load is lifted.

It will be noted that lifting axle I02 carries at its center the pumping lever 68, and on the two sides of the pumping lever (see Figure 7) are the supporting sleeves I03, with the lifting arms I04 and I06 on the ends of the axle. As is shown best in Figure 3, during the pumping operation, pumping lever 69 exerts a force on the axle I02 which force is to the right and upwardly, whereas the lifting arms I04 and I06 exert forces on the axle which forces are to the left and downwardly. Thus, the lifting axle is subjected to directly opposed forcesv with the forces on the ends of the axle tending to balance the force on the center of the axle. Axle I02 is sufficiently sturdy to remain rigid when subjected to these forces, and thus the forces tend to counterbalance each other through the axle, and to the extent that they do counterbalance each other, the forces are not transmitted to the frame.

With the steering handle raised as in Figure 3, if it is desirable to disengage the steering handle from the linkage mechanism, the steering handle is lifted upwardly through steering-handle sleeve 46, and the handle is then swung down with the extreme end of the latching portion I2 riding upon the surface 55 of disc segment 54. Thus, the steering handle is held in this extended position and may be used as a'handle to pull, push and otherwise manipulate the truck. If the steering handle is pulled outwardly when it is not in the raised position, spring I29 immediately returns the elements, including the segment-hook to the position shown, and the handle is held extended. As shown best in Figure '7, upon opposite sides of the steering-handle sleeve 46 are stops 86 which cooperate with suitable stops 98 on bracket 42 to limit the swinging movement of handle 40.

When the handle is held extended by segment 54, the operator may at any time raise the handle to the vertical position, at which time (see Figure 3) the handle automatically drops, with the latch I2 falling behind the rear of the segment. Thus, the handle is held from falling and may be used to elevate the lifting frame when desirable. As shown in the central portion of Figure 1, a load bumper plate 260 extends upwardly from the lifting frame at the forward end of the platform (see also Figure '1) Hinged upon the upper edge of this bumper plate 230 is a shield 262, the upper edge of which rests against the rear wall of the battery housing 200. The bumper plate limits the backward movement of the truck under the load, and shield 262 prevents materials from falling into the space between the forward end of the lifting frame and the battery housing. The truck is thus backed under the load as far as it will go, and the load is then elevated by a pumping movement of the steering handle 40. As the lifting frame moves upwardly, bumper plate 280 is carried toward the battery housing and the upper edge of shield 262 rides upwardly along the housing wall so that there is no interference with the lifting movement of the frame. I As indicated above, the hydraulic ram I24 (Figure 3) acts as an automatic latching mechanism to hold the load at the end of each stroke, and it continues to' act in this capacity while the truck is being wheeled about to thereby move the load to its new location. Referring also to Figure 7, when the load is elevated, it may be is moving downwardlmheel portion I62 swings counterclockwise toward the position shown in Figure 3, and set screw I50 is so adjusted that its lower end is engaged by the heel portion when the lifting frame has returned fromthe elevated position. Due to this engagement, heel portion I62 pushes treadle-locking. arm I42 upwardly out of engagement with latch pin I46, and treadle i6 is released, and the spring acting on load releasing rod I30 returns the elements to the position of Figure 3. Thus, when the treadle is pushed down, the lifting frame automatically returns tothe position of" Figure 3, and the descent of the lifting frameautomatically releases the treadle and closes the valve of releasing rod I30 so that the'mechanism is conditioned of set screw I50 and load releasing rod I32 are released by stepping on a foot treadle I5 which A is rockably mounted by means of a pivot I8 on cross-head I6. Treadle I5 is connected through an adiustable release rod I32 to the upper end of a release lever I34 which is pivoted at its lower end (see Figure 4) on a pivot I36, carried by the frame construction 2I. Release lever I34 is provided with an outwardly extending flange I31 which has an arcuate portion I38 connected to the load releasing rod I Accordingly, load releasing rod I30 is provided with a T-extension I40, the cross-member of which engages the right-hand surfaces of the arcuate portion I33, and the longitudinal portion of which extends through a hole in the arcuate portion I36 and is adjustably attached to the load releasing rod. As pointed out above, the load releasing rod is held inwardly by a spring, and when the rod is pulled to the right, a valve is opened which releases the load. The spring acting on the load releasing rod normally holds foot treadle 15 in its raised position shown in Figure 4, and when the foot treadle I5 is depressed, as shown in Figure 5, the load releasing rod is pulled outwardly sufficiently to release the load.

As has been indicated, it is desirable that the load releasing operation be carried on automati cally to its conclusion when once it is started, and in the present embodiment this is accomplished by providing a releasable latch for holding treadle 15 in its depressed position (Figure 5). Accordingly, a treadle-locking arm I42 (see also Figure 7) is mounted to rock freely upon the extended end of lifting axle I02, and the end of the treadle-locking arm is provided with a latch portion I44 which is adaptedto engage the latch pin I46 rigidly carried by treadle I5.

When the treadle is in its raised position, the treadle-locking arm is held upwardly as shown in Figures 7 and 4, but when the treadle is depressed (as shown in Figure 5) the treadlelocking arm falls, and its latching portion I44 engages the latch pin I46 and holds the treadle depressed. Thus, the operator may remove his foot and the load continues to descend.

The treadle-locking arm I42 is provided with a side bracket I48 which carries an adjustable set screw I50, and lifting arm I04 is provided Whenthe lifting frame 75 forth, it is to be understood that all matter herewith a heel portion I52.

for further use in lifting a load. The adjustments held by suitable lock nuts.

It is important thatsafety means be provided to prevent the elevation of the lifting frame beyond a desirable limit. This is particularly important in the present embodiment where the lifting is accomplished by operating a hydraulic ram as this type of mechanism, gives to the operator tremendous power in moving the lifting frame. Thus if mechanical stops were provided to limit the elevation of the lifting frame, the mechanism might be damaged or broken without the operator realizing that he has reached the limit of movement of the lifting frame In the present embodiment, this difliculty is avoided by providing means to open momentarily the release valve whenever the lifting frame reaches the maximum elevation which is desirable. Referrlng to Figures 4 and 7, accordingly, lifting arm I04 is provided with an integral lug I54 which is adapted to engage the sleeve I56 -(see also Figure 6) of release lever I34 when the lifting arm swingsbeyond a certain limit. In so far as the elevating of the lifting frame is accomplished by swinging the lifting arms I04 and I06, lug I54 engages sleeve I56 of the release lever at any time that the lifting frame is moved beyond a certain predetermined desirable limit. This engagement swings the release lever I34 and pulls releasing rod I30 (see Figure 4) to the right sufliciently to open'the releasing valve, and the hydraulic ram therefore ceases to hold the lifting frame until the releasing valve is permitted to reclose. Thus, when the lifting frame is raised during a particular pumping stroke to the point where the releasing valve is opened, the liftingframe is not held in this position but immediately begins to drop; This dropping or return movement of the lifting frame is sufficient to move lug I54 to the left and permit releasing lever I34 and releasing rod I30 to return to their normal positions so that the releasing valve is reclosed. Thus, even if the load is fully elevated, the pumping operation may be continued indefinitely without danger of injury to the mechanism, as the lifting frame will always return at the end of a stroke the same distance it was raised during that stroke. During this time, the movement of releasing lever I34 causes treadle I6 to swing downwardly, but this moveinbefore set forth, or shown in the accompanying drawings, is to be interpreted as illustrative and not in a limiting sense. r

I claim:

1. In lift truck construction, the combination 7 of: a chassis-having a steering handle and wheels lift a load; operating means to raise said lifting a frame comprising means detachably connected to said steering handle so that the load may be lifted by swinging the steering handle; driving means to move the lift truck so that when a load has been lifted it may be moved to a new location; and control means to control the operation of said driving means including a pair of push buttons mounted on the end of the steering handle so that the operator can start the truck by manipulating the push buttons and can simultaneously steer the truck.

2. In lift truck construction, the combination of: a chassis comprising a supporting frame having mounted thereon a set of wheels and a steering handle; a lifting frame mounted upon said chassis and adapted to be moved to and from a raised position where it engages and lifts a load; means to elevate said lifting frame comprising, a multiple-stroke operating mechanism, and means to detachably connect said operating mechanism to said steering handle so that said steering handle may be swung to operate the operating mechanism and lift the lifting frame; a motor adapted to drive said truck to thereby ,move the truck and the supported load; and control means including a pair of push buttons mounted upon the end .of the steering handle adjacent the hand-grips which push buttons may be manipulated by the operator to cause the motor to move the truck forward or to the rear.

3. In lift truck construction, the combination of: a chassis comprising, a supporting frame, a rear wheel unit mounted to support the rear of said supporting frame, a front wheel unit mounted to, support the front end of said supporting frame, and a steering handle swingably mounted upon said front wheel unit so that the steering handle may be grasped at its free end and may be swung horizontally to steer the truck; a motor unit to drive said truck comprising, an electric motor mechanically connected to deliver' power to said rear wheel unit to thereby move the truck; a battery assembly constituting a source of power to operate said electric motor,

and means to selectively connect said battery assembly to said motor including a pair of operating switches one of which is operated to move the truck forward and the other of which is operated to move the truck to the rear, said switches being positioned away from the truck frame for remote control of the motor; and a load lifting means to elevate a loadwhich is to be moved.

4. In lift truck construction, the combination a of: ,a chassis comprisin a supporting frame, a rear wheel unit mounted to support the rear of said supporting frame, a front wheel unit mounted to support the front end of said supporting frame, and a steering handle swingably mounted upon said front wheel unit so that the steering handle may be grasped at its free end and may motor mechanically connected to deliver power to said rear wheel unit to thereby move the truck; a battery assembly constituting a source of power '70 be swung horizontally to steer the truck; a motor f, unit to drive said truck comprising, an electric to operate said electric motor, and means to selectively connect said battery assembly to said motor including a pair of operating switches one of which is operated to move the truck forward and the other of which is operated to move the truck to the rear, said switches being positioned upon the end of said steering handle so that they may be selectively operated by the hand of the operator; and a load lifting means to elevate a load which is to be moved including means detachably connected to said steering handle so that the load may be lifted by swinging the steering handle and the steering handle may then be disconnected from said load lifting means.

5. In lift truckconstruction, the combination of: a chassis comprising, a supporting frame, a rear wheel unit mounted to support the rear of said supporting frame, a front wheel unit mounted to support the front end of said supporting frame, and a steering handle swingably mounted upon said front wheel unit so that the steering handle may be grasped at its free end and may be swung horizontally to steer the truck; a motor unit to drive said truck comprising, an electric motor mechanically connected to deliver power to said rear wheel unit to thereby move the truck; a battery assembly constituting a source of power to operate said electric motor; a load lifting means to elevate a load which is to be moved; and a control relay assembly which is connected to said battery assembly and to said motor through a plurality of leads, a pair of double switches mounted upon the end of said steering handle so that they may be selectively operated during the steering operation with the operation of one of the switches initiating the movement of the truck forward and the operation of the other switch initiating the movement of the truck to the rear, said switches being connected to said relay assembly through a plurality of leads and each switch being effective when operated to render the other switch ineffective.

6. In lift truck construction, the combination of a chassis having a steering handle and wheels thereon to permit moving of the lift truck, said steering handle having hand-grip means on its free end which may be grasped by the operator; a lifting unit to operatively engage and lift a load so that the load is supported by the lift truck; motive means to move the truck; and control means to control the moving of the truck by said motive means including, a relay assembly, three lines extending from said relay assembly through said steering handle to the free end thereof, and a switch assembly connected to said lines and mounted upon said steering handle adjacent said hand-grip means, said lines comprising a power supply line and two control lines one of which is the forward control line and is connected to said power line to move the truck forward and the other of which is the rear control line and is connected to said power line to move the truck to the rear, said switch assembly comprising a first normally closed switch and a second normally closed switch each of which has one side connected to said power line and a forward normally open switch. which has one side connected to the forward control line and a rear normally open switch which has one side connected to the rear control line, lead means connecting the other side of said forward normally open switch to the other side of said first normally closed switch and connecting the other side of said rear normally open switch to the other side of said second normally closed switch, and operating means to operate selectively said second normally closed switch and said forward normally open switch or said first normally closed switch and said rear normally open switch.

7. In lift truck construction, the combination of: a chassis comprising a supporting frame, a rear wheel unit mounted to support the rear of I said supporting frame, a front wheel unit mounted to support the front of said supporting frame, and a steering handle swingably mounted upon said front wheel unit so that the steering handle may be grasped at its free end and may be swung horizontally to steer the truck; a motor-unit to drive said truck comprising an electric motor -mechanically connected to deliver power to one ing handle away from the truck frame for remote control of the motor; and load-lifting means to elevate a load which is to be moved.

8. A construction as claimed in claim '7, wherein said rear wheel unit is in the form of a pair of wheels mounted upon a single axle and wherein the electric motor is positioned horizontally in said supporting frame forward of said axle.

9. A construction as claimed in claim 7, wherein said supporting frame has mounted at its forward end a battery box housing said battery assembly and wherein a guard plate is hinged at its lower edge to the forward end of said lifting frame and has its upper edge resting against the side wall of said battery box to thereby permit relative movement of said lifting frame without danger of interference by materials extending against said battery box. 7

WILLIAM STUEBING, JR.