US3542227A - Lift truck with ground-engaging means for supporting base of mast - Google Patents

Description

llnited States Patent FOREIGN PATENTS [72] Inventor Stanley E. Farmer .m a h w r H ny ammaa w mm uweo AGGN 3203 6666 9999 1111 l/// 181] 11 2716 8684 1 5322 5090 290 l n 0 n n o n W 80M. r 67r- O 990 m 116 7 8 ZHMd m .m 8 VS suoa G- JNC 0. de N 66 mm d wemwfi a AFPA l:l.l:l. 253 2247 [.Itll.

Primary Examiner-Gerald M. Forlenza Assistant Examiner Portland, Oregon Raymond B. Johnson a corporation of Oregon 1 Attorney-Kolisch & Hartwell [54] LIFT TRUCK WITH GROUND-ENGAGING MEANS FOR SUPPORTING BASE 0F MAST 3 Claims, 6 Drawing Figs.

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ABSTRACT: A lift truck including a wheel-supported frame and a mast mounted adjacent the forward end of the frame, and beyond the wheels supporting the frames forward end, for tilting between inclined and upright positions relative to the frame. Wheels are mounted adjacent the base and on opposite sides of the mast. These wheels occupy a position above e mast inclined, and engage the ground and ith the mast upright.

[56] References Cited UNITED STATES PATENTS 2,092,663 8/1937 Bach the ground with th 214/670 support the mast w Patented Nov. 24, 1970 3,542,227

Sixmley E. FarmEPr INVENTOR LIFT TRUCK WITH GROUND-ENGAGING MEANS FOR SUPPORTING BASE OF MAST This invention pertains to a lift truck, and more particularly,

to such a truck including a mast with ground-engaging means provided for supporting the base of the mast with the latter in an upright position.

This invention is bottomed on the concept that good utilization of warehouse storage space may be achieved if packages are stacked in four adjacent rows, and aisle space is provided for shifting packages in such rows on each side of these four adjacent rows. In such a system, a lift truck having forks which may be extended from its mast may be employed to pick up and deposit packages, on inside rows, by reaching over outside rows. Further explaining, to pickup a package in the row nearest an aisle, the truck operates in the usual fashion. To pick up a package in a row inwardly from an aisle row, the forks in the truck are extended over the aisle row. The aisle space provided, therefore, permits the handling of packages in two rows instead of one.

Lift trucks to be employed in this manner must be constructed to have suitable stability under conditionswhen the forks are extended from the mast and support a load. With the ordinary truck, when a heavy load is held far out in front of the truck, the mass of the truck is not sufficient to keep the wheels supporting the rear end of the trucks frame from lifting off the ground. This invention contemplates a truck which solves this V problem, without interfering with ordinary truck handling capability.

Therefore, a general object of the present invention is to provide a novel lift truck which features means stabilizing it when heavy loads are carried.

More specifically, an object of the invention is to provide such a truck which includes novel ground-engaging means in,- creasing the trucks stability with the mast upright and in the position itoccupies in the picking up or the depositing of a load.

According to a preferred embodiment of the invention, the truck includes a frame with opposite ends supported by wheels, and a mast, assembly mounted adjacent the forward end of the frame and positioned forwardly'of the wheels supporting the frames forward end. The mast assembly is mounted on the frame through means permitting tilting of the assembly between inclined and upright positions. Lift forks for supporting a load are mounted through reach mechanism on a carriage which can move up and down'on the mastassembly. Mounted adjacent the base and on lateral sides of the mast assembly are wheels which augment the support for the mast with the mast upright. With the mast in an inclined position (as when the truck moves with a load) the latter-mentioned wheels are above the ground and in no way interfere with truck mobility.

These and other objects and advantages attained by the invention will become more fully apparent as the description which follows is read in conjunction with the accompanying drawings wherein: I

FIG. I is a fragmentary side elevation illustrating a lift truck constructed according to the invention, with various parts in the truck shown in dash-dot outline with these parts in an extended position;

FIG. 2 is a fragmentary plan .view, further illustrating the truck of FIG. 1;

FIGS. 3, 4 and 5 are simplified side elevations, on a smaller scale than FIGS. 1 and 2, illustrating the proposed lift truck with parts therein shown in different positions during a loadhandling operation; and

FIG. 6 is a simplified fragmentary plan view illustrating how the truck proposed herein may be employed in a warehouse to handle packages stored therein.

Turning now to the drawings, and referring first to FIG. 6, indicated generally at 10 isa lift truck as contemplated herein comprising a vehicle frame 12 supported for travel over'the ground by means ofthe usual front and rear wheel assemblies, or means, shown at l4, 16, respectively. Wheels 16 are dirigible, and steering is performed by turning such wheels utilizing steering wheel 18 which is located in front of an operator's seat 20. The usual drive motor (concealed) is drivingly connected to front wheels 14 to power them.

Considering FIGS. 1- and 2, the lift truck further comprises a vertically extensible mast assembly indicated generally at 22 and disposed forwardly of frontwheels 14. The mast assembly is shown in an upright position in FIG. I. Assembly 22 com prises a pair of laterally spaced outer channel members 24 and a pair of inner channel members 26 telescopically received within the outer channel members for extension upwardly from the outer channel members. The upper ends of channel members 24 are joined by a crossmember 28, and member 28 together with outer channel members 24 constitute an outer mast section in assembly 22. Similarly, the upper ends of the inner channel members are joined by a crossmember 30, and this crossmember together with the inner channel members constitute an inner mast section. As can be seen clearly in FIG. 2, crossmember 28 bows rearwardly to provide clearance for crossmember 30 with vertical movement of the inner mast section.

The mast assembly is mounted on the forward end of frame 12 through a pair of laterallyspaced bracket structures 32 which are joined to the rear sides of outer channel members 24. Bracket structures 32 are pivoted to frame 12 through means such as the pivot connection shown at 33. The pivot mounting accommodates tilting of the mast assembly (between upright and rearwardly inclined positions) about a substantially horizontal axis 34 (see FIG. 1) that extends transversely of the longitudinal axis of the truck. The mast assembly is tilted by means of a pair of laterally spaced fluidoperated rams, such as the one shown at 36 in FIG. 1. The butt end of the rams cylinder'is pivoted through a pivot connection 38 to the frame of the vehicle, and the outer end of the rod in each ram is connected to a bracket structure through a pivot connection 40. FIG 5 shows the mast assembly in its rearwardly inclined position.

Mounted for vertical movement on inner channel members 26 in the inner mast section is a carriage 42. The carriage comprises three upright, elongated, substantially parallel channelpieces 44, 46, 48. Channel pieces 44, 48 are laterally spaced apart from one another with their recessed sides facing downwardly in FIG. 2. Channel piece 46 is positioned between andjoined to pieces 44, 48. The recessed side of piece 46 faces upwardly in FIG. 2. Also forming part of the carriage are rollers, such as rollers 50, suitably journaled on the outer flanges in channel pieces 44, 48. Such rollers are freely received within the elongated channels that extend along the recessed sides of channel members 26, and guide the carriage for vertical movement on the inner mast section.

The inner mast section in assembly 22 is raised and lowered by an upright hydraulic hoist ram indicated in dashed outline at 52 in FIG. 2. The butt end of the cylinder in ram 52 is suitably supported adjacent the base of the mast assembly, and the upper end of the rod in the ram is anchored to a bracket 54 which is secured to crossmember 30 in the inner mast section. With e'xtensionand contraction of ram 52 the inner mast section moves as a unit with the rod in the ram.

Carriage 42 is raised and lowered by means of a conventional chain and pulley mechanism which has been omitted from the drawings in order to obtain better clarity therein.

Further describing truck 10, mounted on the carriage through an extensible reach mechanism indicated generally at 56, is a pair of laterally spaced lift forks 58. In FIG. 1, in solid outline, the reach mechanism is shown in a contracted state, with the lift forks positioned closely adjacent the mast assembly and extending forwardly from frame 12 in the truck. In

channel pieces 44, 48, and are disposed with their recessed sides facing the .recessed sides of such channel pieces, respectively.

The reach mechanism further comprises a pair of scissors assemblies 66, 68 which are similar to one another and which interconnect channel piece 44 with channel member 62, and channel piece 48 with channel member 64, respectively. It should be obvious that the particular form of reach mechanism used is subject to some variation. Details of a reach mechanism similar to the one described herein, while not important to an understanding of the invention, may be found in a prior-filed copending application of Warren et al., U.S. Pat. Ser. No. 713,815, filed Mar. 18, 1968, entitled LIFT TRUCK.

The scissors assemblies in reach mechanism 56 are extended and contracted by means of a crank 70 and a hydraulic ram 72. The butt end of the cylinder in ram '72 is suitably pivotally mounted on channel piece 46 in the carriage, and the outer end of the rod in the ram is pivoted at 74 to crank 70. Contraction of ram 72 causes contraction of the scissors assemblies, and extension of the ram causes extension of the assemblies.

Lift forks 58 are joined by a hook 76 extending along their back sides in FIG. I, and this hook fits over a bar 78 joined to a plate 80. Each fork is supported additionally by a hook, such as hook 79 in FIG. 1, disposed beneath hook 76 and engaged with a bar 81 joined to plate 80. Plate 80 is part of a side-shift mechanism 82 which is actuatable to produce side shifting of the forks relative to frame section 60 in the reach mechanism.

' Describing further details of this side-shift mechanism as illustrated in FIG. I, joined to the back of plate 80 is a hook 84 mounted for side to side sliding movement on upper plate 65 fastened to frame section 60. A ram 88 is provided for shifting plate 80 laterally as accommodated by sliding movement of hook 84. One end of the ram is suitably mounted on plate 80, and its opposite end is suitably connected to frame section 60. Details of a side-shift mechanism similar to the one just described may be found in a prior-filed copending application of Robert J. Kroupa, U.S. Pat. Ser. No. 662,149, filed Aug. 21, 1967, entitled SIDE-SHIFT APPARATUS FOR A LIFT TRUCK, which was issued as Pat, No. 3,460,700.

According to the present invention, means is provided for supporting the base of mast assembly 22 with the same occupying its upright position. In the preferred embodiment illustrated, such means comprises a pair of wheels, or ground-engagable means, 90. As can be seen clearly in FIG. 2, wheels 90 are disposed laterally outwardly of outer channel members 24 in the mast assembly, and are journaled on axles 92 joined adjacent the bases of such members. It will be noted in FIG. 1 that with the mast assembly in an upright position, wheels 90 are in lowered positions where they engage the ground and provide support for the mast. Further, it will be noted that wheels 90 are located well forwardly of front wheels 14 in the truck, near the forward extremity of the mast assembly.

Explaining now how the truck described herein operates, and referring to FIGS. 3-6, in FIG. 6 there is illustrated at 94 portions of a warehouse floor. In the warehouse, palletized loads. such as packages 96, may be stored in four adjacent rows. such as the rows shown at 98, I00, I02, 104. Aisle space 106 is provided on one side of the rows, and aisle space 108 is provided on the opposite side of the rows.

With the lift truck of the invention, a package 96 may be readily picked up from an inner row, such as inner row 100, where such is not obstructed by packages in an outer row, such as row 98, without losing stability in the truck, and even though the load may have considerable mass. Further explaining, and assuming that a package 96 in row 100 is present which is above the elevation and not obstructed by any packages in front of it in row 98, to pick up such a package the truck first is maneuvered with its mast rearwardly inclined to a position directly in front of row 98 and facing the package which is desired to be picked up. Through operation of rams 36, the mast assembly may then be tilted to an upright position. With the assembly upright the mast assembly may be extended to elevate the carriage and forks, whereby the forks are at a suitable elevation to move over the top of any packages in row 98.

Reach mechanism 56 may then be extended to shift the forks to a position beneath the package 96 which is in row 100. Raising of the forks slightly will then operate to pick up the package. FIG. 3 illustrates in side elevation the truck, package and forks as they might appear after picking up such a package. It will be noted with reference to this FIG. that wheels at the base of the mast assembly are lowered, and in a position engaging the ground at a point located forwardly of front wheels 14. As a consequence, even though the package 96 which has been picked up may have considerable mass and is held in a position relatively far in front of the truck, a stable condition is maintained, with the mass of the truck counterbalancing the mass of the load about wheels 90.

Reach mechanism 54 may then be contracted to shift the forks and load rearwardly whereby the load becomes positioned close to the mast assembly as shown in FIG. 4 Either at this time, or perhaps after the truck has been backed off slightly from the row of packages, the mast assembly may be inclined rearwardly from its upright position to tilt the forks slightly whereby the load becomes more firmly lodged on the forks as is conventional with lift truck operation. Also, the forks and package may be lowered to positions closely adjacent the ground through contraction of the mast assembly. With tilting of the mast assembly from its upright to its rearwardly inclined position, wheels 90 move upwardly from the ground to leave the vehicle and load supported entirely by the truck wheels 14, 16. This condition of the parts, with the mast tilted, and the forks and package lowered, is illustrated in FIG. 5, and with such a condition, the load is in position for transport. The vehicle may then be maneuvered in the usual manner.

Thus, the proposed lift truck has a number of important advantages distinguishing it from prior known trucks. Of principal importance is the provision of ground-engaging means mounted adjacent the base of the mast assembly. With such means provided which engages the ground with the mast in an upright position, a load may be supported at a considerable distance from the front of the truck, as in the type of load-handling operation described above, without the truck losing its forward stability. The ground-engaging means engages the ground at a point spaced forwardly of the front wheels supporting the truck frame, and this increases the moment arm through which the mass of the truck acts to counterbalance a load.

Where, as in the preferred embodiment described herein, the ground-engaging means comprises laterally spaced wheels disposed outwardly of the mast assembly, the truck can be moved over the ground with such wheels providing rolling contact between the base of the mast and the ground. The wide lateral spacing present in the wheels ensures good support for opposite sides of the mast.

While a preferred embodiment of the invention has been described herein, it is appreciated that variations and modifications are possible without departing from the spirit ofthe invention.

Iclaim:

1. A lift truck comprising:

a vehicle frame having front and rear ends with dirigible wheel means supporting the rear end of the frame and power-driven wheel means supporting the front end of the frame;

a mast assembly and means mounting said assembly on said frame with such disposed forwardly of the power-driven wheel means supporting the frame at said front end, the means mounting said mast assembly accommodating movement of the assembly relative to the vehicle frame between inclined and upright positions;

load-support means and reach mechanism mounting the load-support means on said mast assembly with the loadsupport means disposed forwardly of the mast assembly, position, and a lowered position where it engages the said reach mechanism being actuatable to thrust the loadnd t r vid support for the mast assembly with the support means outwardly in a forward direction from the l t i i said upright position.

m t a em ly means mounted on Said Teach mechanism 2. The lift truck of claim 1, wherein said grund-engagable j f g Sald pp means transversely relative support means comprises a pair of laterally spaced wheels.

to reach mechamsmiand 3. The lift truck of claim 2, wherein said mast assembly ground'engagable Support means mounted n the mast comprises an outer mast section including a pair of laterally sembly disposed forwardly of the power-driven wheel means supporting the front end of the vehicle frame, said support means having a raised position where it is above 10 the ground with said mast assembly in its said inclined spaced mast members, and said wheels are disposed laterally outwardly of said members.

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