US2514052A

US2514052A - Industrial truck

Info

Publication number: US2514052A
Application number: US752593A
Authority: US
Inventors: Gunning Alfred Wayne
Original assignee: Clark Equipment Co
Current assignee: Doosan Bobcat North America Inc
Priority date: 1947-06-05
Filing date: 1947-06-05
Publication date: 1950-07-04
Anticipated expiration: 1967-07-04

Description

July 4, 1950 A. w. GUNNING I INDUSTRIAL TRUCK 3 She'ets-Sheet 1 Filed June 5, 1947 fizz/8226a".-

y 1950 A. w. GUNNING ,5 ,052

INDUSTRIAL mucx Filed June 5, .1947 3 Sheets-Shasta 2 y 1950 A. w. GUNNING 2,514,052

INDUSTRIAL 'mucx Filed June 5, 1947 3 Sheets-Sheet 3 as an IIIIIIIII In V612 ivr flyred Wgy/w Gunru'gy,

Patented July 4, 1950 INDUSTRIAL TRUCK Alfred Wayne Gunning, Battle Creek, Mich., as-

signor to Clark E chanan, Mich.,

quipment Company, Bua corporation of Michigan Application June 5, 1947, Serial No. 752,593

4 Claims.

This invention relatesto industrial trucks and more particularly is directed to an improved load raising and supporting mechanism for industrial trucks of the well known fork type.

In the majority of industrial trucks of the fork type now in use, there has been encountered much difliculty in operations where the truck must pass through a low doorway in going from one section of a warehouse to another, or in carrying goods into a box car or the like where there is low overhead clearance, inasmuch as in most trucks of this type, the elevating mechanism, which carries 'the load supporting carriage, of necessity begins to extend upwardly as soon as the load is lifted, and even in a carrying position projects to a point where it cannot clear certain types of car doors and certain types of door openings within warehouses or mercantile buildings.

It is a primary object of the present invention to provide an industrial truck wherein the load supporting carriage can be raised'to the full extent of the stationary uprights before the inner or telescoping uprights begin to raise. With this construction, it is possible to pick up and carry loads through doorways having no more overhead clearance than the vertical extent of the uprights or mast when in lowered position, and to maneuver and dispose material within the door of a box car or in buildings with low overhead height without the'necessity of increasing the vertical height of the upright structure.

More specifically, the present invention involves an improved upright and lifting arrangement whereby the forks of the machine can be raised up to a height suilicient for tiering two stacks of material without the necessity of increasing the overhead height of the machine, and which will still allow for very high lifting when there is no overhead obstruction.

For example, in one model of truck equipped with the present design, it is possible, with an upright structure having an over-all height of 83" collapsed position, to lift the fingers from ground level to 63" above the ground prior to any increase in the overall height of the upright structure. With this same structure, a maximum lift height of 130" can be obtained when the mast structure is fully extended.

The present invention contemplates accompli shing these objects by the provision of a three to one lifting ratio between the horizontal cylinder and the load supporting carriage. The design is such that the inner slides do not move vertically until the load supporting carriage has reached a position substantially at the top of the stationary uprights. From then on, the carriage does not move relative to the inner up- I rights but moves conjointly therewith as the inner uprights are telescoped upwardly relative the stationary uprights.

The present construction has several additional advantages in that the horizontal cylinder is reduced in length, thereby allowing the operator more vision forwardly between the uprights above the cylinder when he moves into position to pick up a load or the like.

Another advantage secured by the present invention is the provision of means for insuring that the load supporting carriage when moved from its extreme upper height downwardly, will not move relative to the inner slides, but will first move the inner slides downwardly therewith until the inner slides are fully telescoped into the stationary uprights. At this point, th mechanism is so designed that the carriage can then move downwardly relative to the inner slides to its lowermost position at the bottom of the stationary uprights. This is accomplished by means of a novel latching mechanism consisting of a 2 way latch operating between the upper end of the stationary uprights and the upper end of the telescoping uprights. The latch is controlled by the movement of the telescoping uprights and the load supporting carriage.

Other objects and advantages of the present invention will appear more fully from the following detailed description which, taken in conjunction with the accompanying drawings, will disclose to those skilled in the art, the particular construction and operation of a preferred form of the present invention.

In the drawings:

Figure 1 is a top plan view of an industrial truck embodying the present invention.

Figure 2 is a side elevational view of the truck shown in Figure 1 with the upright structure shown in its raised position by dotted lines.

Figure 3 is a perspective view of the upright structure in its lowered position.

Figure 4 is a corresponding view of the upright structure in fully raised position.

Figure 5 is a detailed perspective view showing the latching mechanism between the load supporting carriage and the inner slides; and

Figure 6 is a diagrammatic view of the chain or cable arrangement for effecting the lifting action. V

' Referring now in detail to the drawings, an industrial truck of any well-known type is generally indicated at 5 and includes the body 6, the driv- 3 ing wheels I, the steering wheels I and the rear counterweight l.

A driver seat is indicated generally at ll. adiacent the steering column i2, and the various controls for forward and reverse drive of the vehicle are indicated at [3.

The control mechanism for the lifting and tilting action of the uprights is actuated by control levers i4, mounted above the engine compartment adjacent the driver seat.

The upright construction generally comprises a pair of pivotally mounted stationary uprights II, which preferably adjacent their lower ends are pivotaily supported for forward and rearward tilting. These uprights preferably comprise channel members maintained in laterally spaced relationship at their lower ends by a suitable cradle member which supports the base end of the horizontal lift cylinder it, and at the upper end by the cross member II which may be welded or bolted to the outer sides of the channels l5 and extends rearwardly therebetween.

Disposed within the main uprights I! are a pair of secondary uprights or inner slides it which also preferably comprise channel members mounted in facing relation and guided on suitable wear strips I! for sliding movement vertically within the channels ii. The channels it, at their upper ends, are secured together by means of a cross member 20, which cross member is provided with a depending flanged portion 22, shown more in detail in Figure 3, carrying brackets 23, upon which are mounted rotatable sprockets.

Adjacent their lower ends, the outer stationary uprights I! are provided with brackets 24 which are connected to the extending ends of piston rods 25 to provide for forward and reverse tilting action of the entire mast structure about the pivotal mounting of the uprights ii.

The cylinder ii is provided with a piston disposed therein and having the extending piston rod 28, which, at its upper end, terminates in a crosshead 21, carrying sprockets at each side thereof, indicated generally at 28. Mounted on the uprights l5 between the bracket 24 and the upper cross member I1, is a transverse bracket II, which bracket carries suitable sprocket members 32, disposed in substantially the same plane as the sprockets 28 of the crosshead 21. The inner slides it, at thei lower end, are also provided with a transverse spacing member 33, carrying sprockets 34 adjacent each side thereof, and also arranged in substantially the same planes as the

sprockets

28 and 32.

In the construction thus far. described. suitable chain means are anchored on the crosshead 21, as indicated at the anchoring points 35, in Figure 5, and thence extend downwardly and are trained about the stationary sprockets 32, carried by the bracket 30, fixed to the rear of the stationary uprights. This portion of the chain means is indicated by reference numerals 36. The chains are then trained about the sprockets and vertically upwardly over the sprockets 28 carried by the crosshead 21. This portion of the chain means is indicated by the reference numerals 31. After leaving the sprocket 28, the chain means extends downwardly within the inner uprights l8 to the sprockets 34, carried at the lower end of the uprights it and secured in position by the transverse bracket 33. This run of the chain means is indicated by the reference numerals 38.

After being trained around the sprockets 34,

. 4 i the chain means extends vertically from the lower end of the inner uprights II to the upper end thereof, and is trained over the sprockets carried by the bracket 23 on the cross plate 22. This run of the chain is indicated by reference numerals 33, and it will be noted that in the position shown in Figure 3, there is provided a right angle link 4| in this run ofthe chain inasmuch as the sprockets carried by 'thebrackets 23 are disposed at right angles relative to the planes of the

sprockets

23, 32 and 34. The chain again extends downwardly between the two runs 38, and, at its lower end, is anchored to the load supporting carriage, indicated generally by the reference numeral 42. This load supporting carriage, as will be more apparent mm 1, 2 and 5, comprises a body member extending forwardly of the uprights l3 and having vertically spaced

face plates

43 and 44 upon which are mounted L shaped lift fingers, indicated generally at 4!. The body member 42 also has a-rearwardly extending bracket portion on each side thereof, which extends inwardly between the uprights and is adapted to carry suitable roller members engaging the flanged faces of the inner channels it, whereby the carriage is guided for vertical movement relative to the inner slides and may roll upwardly and downwardly therein.

These bracket portions are indicated at 40 in Figure 5 and extend substantially across the face of the inner uprights it on opposite sides of the crosshead 21 and its associated sprockets 23.

The operation of this lifting mechanism will be more apparent from an examination of the diagrammatic showing in Figure 6 of the drawings, in which the structural portions of the mechanism have been eliminated to show the movement of the chaidmechanism during the raising and lowering operations. The sprocket wheels have been given the same identifying numerals in this figure, and the upper sprockets carried by the bracket 23 at the upper ends of the inner slides II, have been identified at 23'.

The position of the mechanism in the diagrammatic showing at A shows the forks 45 in lowermost position and with the other parts of the mechanism approximately in the position shown in Figure 3.

As the hydraulic pressure within the lift cylinder It acts to extend the piston 2i vertically, the sprockets 28 move upwardly being carried on the end of the piston, andsince this upward movement produces a three to on ratio of movement of the lift forks, the position of the sprockets 28 changes, while the position of the sprockets 23' and 34 remains the same until such time as the forks are moved to the upper ends of the inner slides, which positionis shown at B in Figure 6.

It will be noted that during this movement, the piston has traveled the distance indicated by the movements of the sprockets 28 and that this has resulted in a complete raising of the forks 45 to the upper end of the inner slides carrying the sprockets 23'. The anchor sprockets 32 have, of course, remained stationary, being fixed against movement, and the inner slides having remained stationary, the sprockets 34 and 23' also have not moved.

As the piston is'further extended, the inner slides and the forks move vertically upwardly as a unit relative to the stationary mast l5, until they finally arrive at their uppermost position, indicated at C in Figure 6. It will be noted that while th fixed sprockets 32 are still in the same position, the piston actuated sprockets 28 have moved upwardly approximately again as far as they moved in going from position A to position B. However, this movement has resulted in almost a complete raising of the sprockets 34 and 23' to a position where the inner uprights it are fully extended except for that portion thereof necessary to be maintained in the upper ends of the uprights ill for stabilizing purposes.

Figure 2 of the drawings indicates diagrammatically the fork position at the three shown at A, B, and C in Figure 6.

It will be apparent that by anchoring one end of the chain of the movable sprockets 28 and training it over the stationary sprockets 32, a three to one lifting ratio is provided so that the forks are raised three inches for every inch of extension of the piston. As a result, since the piston and cylinder in collapsed position are approximately only of the height of the stationary uprights I5, the movement of the piston into a position at the upper end of the uprights I5 results in raising the load supporting carriage up into a position substantially in the upper ends of the stationary uprights. Further movement of the carriage 42 relative to the inner slides is, of course, not possible in this fully raised position, and consequently from this time on, the carriage 42 moves conlointly with the inner slides vertically out of the stationary supporting uprights l5.

Another movement of the piston head of approximately of the length of the inner slides raises the inner slides to their fully extended position, again because of the three to one lifting ratio.

In a mechanism of this type, it is highly desirable that the inner slides be prevented from moving vertically until such time as the load supporting carriage has reached the upper end of the inner slides. It is further highly important that when being lowered from the fully raised position, such as indicated at C in Figures 2 and 6, that the inner slides move downwardly conjointly with the load supporting carriage, in order to prevent the carriage moving relative to these slides. until after the slides have again been nested completely within the stationary slides l5. For this reason, a latching mechanism has been developed which is shown most clearly in Figure 5, for con-- trolling the relation of movement of the inner slides relative to the load supporting carriage and to the stationary uprights under the .various conditions outlined above.

This latch mechanism briefly comprises the brackets 50 mounted on the rear flange of the slides ll adjacent their'upper ends and carrying a T-shaped latch member 52, which is pivotally mounted thereon and which preferably has a depending latch carrying arm and normally extending actuating arms. The latch portion of the members 52, comprises a depending arm 53, carrying oppositely projecting

latch detents

54 and 55, respectively. The latch detent 55 is adapted to have latching engagement with a latch dog 56, mounted on each of the brackets 46 of the body portion of the load supporting carriage 42. The opposite detent 54 of the arms 53 is adapted to have latching engagement with suitable latch dogs 51, carried on the inner surface of the cross member ll, permanently secured to the upper end of the stationary uprights l5.

Suitable spring mounted control buttons or plungers 58 are provided in the flanged portion of the member I1 and are adapted to be engaged by the cam portions 59 of the latch members 52 points latches are thus engaged with the dogs 51, the

inner uprights cannot move vertically and the load supporting carriage, of course, then traverses the vertical extent of the uprights ll, moving into the position shown in Figure 5.

As it moves into this position, the upper ends of the brackets 46 have suitable surfaces adapted v to engage cam surfaces 8|, formed on the latches 52, which rock these latches out of engagement with the dogs 51, thereby allowing. the inner uprights II to be released from locked engagement with the outer uprights and allowing the inner slides to then move upwardly coniointly with the load supporting carriage 42.

When the mechanism has reached'its uppermost position, however, and it is desired to lower the forks 45, initial lowering movement brings the dogs tents 55, thereby locking the load supporting carriage 42 securely to the uprights it, so that the carriage and the uprights must move downwardly in conjoint relation. They thus move downwardly to a point slightly below the position shown in Figure 5, at which time, the latches have the cam surfaces 59 thereof, engage the buttons 5|, thereby rocking the latches out of engagement with the dogs 58 and releasing the load supporting carriage for further load lowering movement.

In normal operation of the mechanism thus far described, it has been found that the load supporting carriage will travel to the upper end of the inneruprights l8 before these uprights besin to move, primarily because of the fact that a the uprights are held against movement by the relationship of the sprockets at opposite ends thereof, over which the lift chains are trained. It has also been found that in moving from uppermost position 0, downwardly, the load supporting carriage has a. tendency to stay at the upper ends ofthe uprights I I, so that it moves downwardly conjointly with the uprights until the uprights bottom in their collapsed position at which time the forks continue their downward movement.

However, it is desirable that the latch mechanism be provided to insure this proper sequence of movement, and the simplified type of construction herein disclosed provides for positive locking of the uprights in the manner described.

It is therefore believed apparent that the present invention provides a novel type of lifting arrangement, whereby the load supporting carriage can be lifted substantially to the upper end of the stationary uprights before the overall height of the lift mechanism is increased and thus facilitate the picking up and transporting of loads through low. doorways or into box cars or the like, without increasing the mast height. This also allows for tiering up to two loads, one on top of the other, without the necessity for increasing the overall height of the machine. The latch mechanism, of course, provides a safety factor to insure the proper sequential movement of the lift mechanism.

I am aware that various changes may be made in certain details of the present construction without in any way departing fr m the underly- 56 into engagement with the latch de- 7 ing principles of the present invention, and I therefore do not intend to be limited except as defined by the scope and spirit of the appended claims.

I claim:

1. In an industrial truck having a vertical mast at one end thereof, telescoping members guided for vertical movement in said mast, a load supporting carriage guided for vertical movement in said telescoping members, raising means carried by said mast for initially raising said carriage to the upper end of said telescoping members and for then raising said members and carriage conjointly relative to said mast, and latch members at the upper end of said telescoping members normally holding said members against raising movement relative to said mast, including means on said carriage operable when in raised position relative to said telescoping members for disengaging said latch members from said mast and for locking said carriage and telescoping members ior'conjoint movement.

2. In an elevating mast for an industrial truck having a fixed mast, a telescoping inner mast guided therein, and a load-supporting carriage guided in said inner mast, an extendible cross head insaid masts, a flexible member received between said most and cross head and operable upon extension of said cross head for first raising said carriage to the upper end of said inner movement.

8 3. In an elevating mast for an industrial truck having a fixed mast, a telescoping inner mast guided therein, and a load-supporting carriage guided in said inner mast, an extendible cross head in said masts, a flexible member received between said masts and cross head and operable upon extension of said cross head for first raising said carriage to the upper end of said inner mast, and thereafter conjointly raising said inner mast and carriage within said fixed mast, and latch means operative to lock said carriage and inner mast against relative movement whenever said carriage is at the upper end of said inner mast and said inner mast is not bottomed in said fixed mast.

4. In an elevating mast for an industrial truck having a fixed mast, a telescoping inner mast guided therein, and a load-supporting carriage guided in said inner mast, an extendible cross head in said masts, a flexible member received between said masts and cross head and operable upon extension of said cross head for first raising said carriage to the upper end or said inner mast, and thereafter coniointly raising said inner mast and carriage within said fixed mast, and T-shaped latch means pivoted at the upper end of said inner mast selectively operable to lock said inner mast against relative telescoping movement or to lock said carriage and said inner mast against relative movement.

ALFRED WAYNE GUNNING.

' REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number -Name Date 1,900,195 Butterworth Mar. '7, 1933 2,261,930 Abbe Nov. 11, 1941