US3608760A - Lift truck with horizontally slewable load carrier - Google Patents

Abstract

A lift truck is provided with a lift mast having a horizontal slewable load carrier. In one aspect of the lift truck the body thereof is provided with an operator''s cab having a load-bearing roof onto which the load carrier can lower its load after being horizontally slewed to a laterally facing position. In another aspect of the lift truck, the fixed and movable upright guides of the lift mast are aligned longitudinally of the lift truck with the load carrier being mounted to the movable guide for vertical movement and for horizontal slewing.

Description

United States Patent Inventors Maurice J. McIntyre Coquitlam, New Westminister, British Columbia, Canada; John R. Newton, Salem, Oreg. App]. No. 840,758 Filed July 10, 1969 Patented Sept. 28, 1971 Assignee Skagit Corporation Sedro Woolley, Wash.

Continuation-impart of application Ser. No. 740,707, June 27, 1968, now abandoned.

LIFT TRUCK WITH HORIZONTALLY SLEWABLE LOAD CARRIER 4 Claims, 6 Drawing Figs. US. 214/654, 214/731, 214/730, 214/75 R Int. Cl. B66! 9/18 Field of Search 214/654, 1 731 [56] References Cited UNITED STATES PATENTS 2,684,165 7/1954 Hill 214/654 2,748,966 6/1956 GOhl'ke 214/731 3,225,949 12/1965 Erickson.. 214/731x 3,335,879 8/1967 Shaffer 2l4/654X FOREIGN PATENTS 588,910 12/1959 Canada 214/654 Primary Examiner-Gerald M. Forlenza Assistant Examiner-George F. Abraham Attorneys-Robert C. Smith and Plante, Hartz, Smith &

Thompson ABSTRACT: A lift truck is provided with a lift mast having a horizontal slewable load carrier. in one aspect of the lift truck the body thereof is provided with an operator's cab having a load-bearing roof onto which the load carrier can lower its load after being horizontally slewed to a laterally facing position. in another aspect of the lift truck, the fixed and movable upright guides of the lift mast are aligned longitudinally of the lift truck with the load carrier being mounted to the movable guide for vertical movement and for horizontal slewing.

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sum 5 [IF 5 INVENTORS MAURICE J. MclNTYRE JOHN R. NEWTON ATTORNEYS FIG== 6 LIFT TRUCK WITI-I HORIZONTALLY SLEWABLE LOAD CARRIER This application is a continuation-in-part of a copending U.S. Pat. application entitled Lift Truck with Horizontally Slewable Load Carrier," Ser. No. 740,707 filed June 27, 1968, now abandoned.

This invention relates to lift trucks. More particularly, this invention relates to lift trucks adapted to handle large, elongated loads such as stacked lumber in restricted areas.

Life trucks designed to handle large, elongated loads have been proposed wherein a load carrier, such as a fork lift carrier, can be disposed in a forward facing position relative to the truck to pick up a load and then slewed to a laterally facing position to place the elongated load parallel to the truck for transport. These lift truck designs are intended to facilitate transport of elongated material along narrow aisles and yet permit front end loading and unloading. However, the load capacity of such lift trucks is often limited, to a maximum weight or width or both, by lift truck structure that cannot withstand the forces imposed by large loads, or that unbalances the truck when the load is slewed to a laterally facing position, or that blocks the operator's lateral line of sight when the load is slewed to a laterally facing position.

A primary object of this invention is to provide a lift truck wherein a load carrier is adapted to be horizontally slewed from a forward facing position to a laterally facing position and to overlay the load bearing roof of an operators cab when in the laterally facing position. Another object is to provide such a lift truck wherein the lift mast fixed and movable guides are mounted by the truck body parallel with the longitudinal axis of the body with the load carrier horizontally slewable relative to the lift mast guides.

These and other objects and advantages of the invention will become apparent from the following description and the accompanying drawings of which:

FIG. I is a side elevation view of a preferred embodiment of the invention;

FIG. 2 is a front elevation view of the FIG. 1 embodiment;

FIG. 3 is a plan view in partial cross section taken along the line 3-3 of FIG. 2;

FIG. 4 is a perspective view of the FIG. 1 embodiment with certain components blown apart in assembly diagram form;

FIG. 5 is a front elevation view of another embodiment of the invention; and

FIG. 6 is a vertical cross section taken along the lines 6-6 of FIG. 5.

In brief, the lift truck of the present invention comprises a body carried by forward and rearward wheel assemblies and mounting a lift mast. The lift mast includes a first guide fixed against vertical reciprocity movement, a second movable guide mounted by the first guide for vertical reciprocatory movement, a load carrier mounted by the movable guide for vertical reciprocity movement and adapted to be horizontally slewed, means for vertically raising and lowering the movable guide and the load carrier, and means for horizontally slewing the load carrier.

In one aspect of the invention, the body is provided with an operator's cab having a reinforced load bearable roof, and the lift mast is so constructed that when the load carrier is raised to an elevation exceeding that of the body cab, the load carrier and its load can be slewed to overlay the cab. Placing the load over the cab permits more even distribution of the load on the vehicle thereby enabling the transport of heavier and wider loads with a greater degree of stability. In this aspect of the invention, the operator's forward line of sight is through the front and framework of the body, and his lateral line of sight to both sides is completely unobstructed by the load.

In another aspect of the invention, the fixed and movable guides of the lift mast are mounted parallel with the lift truck longitudinal axis and the load carrier is pivotally mounted to the movable guide such that it is substantially perpendicular to the stationary guide when in its forward facing position and is substantially parallel to the fixed guide when in its laterally facing position. The fixed guide is preferably pivotally mounted for slight pivotal movement on a horizontal axis and means to pivot the fixed guide about such axis are provide to afford tilting adjustment of the load carrier when the latter is in a forward facing position. In this aspect of the invention, the structure of the fixed and movable guides is not mounted for horizontal slewing movement and therefore a massive vertical pivot mechanism is not required to accomplish the required horizontal slewing of the load carrier. This aspect not only reduces the structural requirement of the lift mast but also permits reduction of the size of the lift mast elements so that a greater portion of the body width can be effectively utilized to accommodate a loaded laterally facing lift carrier with the load center being maintained adequately close to the longitudinal axis of the vehicle.

Referring to the FIGS., a preferred embodiment of the lift truck of this invention is a rear-engine vehicle comprising a body 10, forward and rearward wheel assemblies 12 and 14 on which the body is carried, and a lift mast assembly 16. The body is a low silhouette structure with a height sufficient to accommodate the necessary head room in an operators cab 18. The roof 20 of the cab is a reinforced structure designed to bear the weight of a load carried by the lift mast assembly. The roof structure comprise a pair of vertical frames, each having a cutout section along their upper sides as shown in FIG. 4, and a plurality of overhead crossbars connected to and extending between the upper sides of vertical frames. As thus structured, the cab roof constitutes a load supporting deck onto which the load carrier can lower its load for transport without continued force exerted on the lift mast.

The lift mast comprises a first guide 22 that is fixed against vertical reciprocity movement, a second movable guide 24 mounted by the fixed guide for vertical reciprocity movement, a load carrier 26 mounted to the movable guide for vertical reciprocatory movement and adapted to be horizontal slewed, means 28 for effecting vertical reciprocatory movement of the movable guide and the load carrier, and means 30 for effecting horizontal slewing of the load carrier. The fixed guide is mounted to one end of a horizontal crossbeam 32, which is itself pivotally mounted to the axle housing 34 of the front wheel assembly such that the fixed guide can be pivoted forwardly and rearwardly about a horizontal axis. Means 36 are provided to effect this slight pivotal movement of the fixed guide. The fixed guide is aligned parallel with the longitudinal axis of the lift truck and positioned adjacent to the inward of one of the front wheel sets of the front wheel assembly.

The fixed guide comprises forward and rearward upright legs, 36 and 38, brace members 48 connecting the two legs, and a crosshead 50 connecting the top ends of the two legs. The forward leg (seen in cross section in FIG. 3) is structurally composed to provide a rearwardly opening guide channel. The rearward leg (seen in cross section in FIG. 3) is structurally composed to provide a main guide channel opening laterally inward toward the opposite side of the vehicle and a secondary forward-opening guide channel on the backwall of the main channel. The intermediate crossbraces are rigidly connected to the outboard sides of the forward and rearward legs. The base member is rigidly connected to the crossbeam 32.

The movable guide comprises forward and rearward upright legs, 44 and 46, intermediate brace members 48 connecting the two legs, and a cross head 50 connecting the top ends of the two legs. The forward leg 44 (see in cross section in FIG. 3) is structurally composed to provide a forward-opening guide channel fitted into the rearward opening guide channel of the forward fixed guide leg 36, and a rearward opening guide channel. The rearward leg 46 (see in cross section in FIG. 3) is structurally composed to provide a laterally outward opening guide channel fitted into the laterally inward opening guide channel of the rearward guide leg 38, and a laterally inward opening guide channel. Sets of forward and rearward movable-guide leg roller bearings 52, 54 and 55 are provided to vertically guide the movable guide legs as the latter vertically traverse the fixed guide legs. Roller bearings 52 and 54 are joumaled to the fixed guide legs and designed to track in the adjacent guide channels of movable guide legs. Roller bearings 55 are journaled to the respective movable guide leg and designed to track in the adjacent guide channel of the fixed guide leg. The forward roller bearings 52 are journaled for rotation on axis aligned parallel with the longitudinal axis of the vehicle. The rearward roller bearings 54 are journaled for rotation on axis aligned laterally perpendicular to the longitudinal axis of the vehicle, and the rearward roller bearings 55 are journaled for rotation on axis aligned parallel with the longitudinal axis of the vehicle.

The load carrier 26 is mounted to the movable guide by a carriage 56 that is adapted to track along the movable guide. The carriage comprises a framework 58 and a load carrier pivot mount 60. The box framework 58 is provided with roller bearings 62 joumaled to the forward end section of the framework and designed to track in the adjacent rearward opening guide channel of the movable guide forward leg, and with roller bearings 64 joumaled to the rearward end section of the framework and designed to track in the adjacent inwardly opening guide channel of the movable guide rearward leg. The forward roller bearings are joumaled for rotation on axis aligned parallel with the vehicle, and the rearward roller bearings are joumaled for rotation on axis aligned laterally perpendicular to the longitudinal axis of the vehicle. The load carrier pivot mount is rigidly connected to the forward end section of the framework and extends forwardly therefrom, and is provided with pivot joumaled mounting openings 66 top and bottom at the forward end thereof and with an opening 68 through the center thereof.

As can be seen from FIG. 3, the forward and rearward legs of the fixed and movable guides are laterally offset with the rearward legs being slightly outboard of the forward legs. Consequently, the forward and rearward end sections of the framework are also laterally offset from one another and are connected by askew top and bottom sections of the framework.

The load carrier 26 comprises a carrier frame 70 and a pair of lift forks 72. The carrier frame comprises a peripheral box beam framework with intermediate vertical box beam braces. The frame is pivotally mounted to the forward end section of the load carrier pivot mount 60 by means such as a journal shaft 74. The lift forks are generally L-shaped members, the upper ends of which are pivotally suspended by cross rods 76 mounted by the carrier frame. The lift forks extend below the carrier frame a sufficient distance to contact the driving surface when the carriage and the carrier frame mounted thereto have been lowered to their lowest levels.

The lift forks 72 may be positioned along their respective cross rods 76 to vary the spacing between them. In FIG. a preferred means for spacing each lift fork comprises an arcuate fork shifter member 77 pivotally hinged to the base of carrier frame 70 at 79 for movement parallel to the plane of the carriage frame. The upper end of member 77 is provided with an arcuate bolt 81 designed to be engaged by a follower rod 83. The upper end of the respective lift fork is mounted by a retainer sleeve 85 which is slidably mounted on the respective cross rod 76 and which mounts follower rod 83. One end of a hydraulic cylinder assembly 87 is pivotally mounted to the side of carrier frame 76 and the other end is pivotally mounted to the fork shifter member 77. By this arrangement, the extension and retraction of the cylinder assembly 87 will efiect lateral shifting movement of the respective lift fork, through pivotal movement of the member.

The means 28 for effecting vertical reciprocatory movement of the movable guide and load carrier comprises a telescoping hydraulic ram 78. The base of the ram cylinder is mounted to the base member of the fixed guide. The upper end of the ramrod mounts a sheave encased in a load-bearing bracket 80, the bracket being connected to the crosshead of the movable guide. A chain 82 is reeved over the sheave and is attached at one end to the upper end of the ram cylinder and at the other end to the carriage. Thus, when the ramrod is extended the bracket 80 will lift the movable guide in a 1:1 ration and the chain will lift the carriage in a 2:1 ratio.

The means 30 for horizontally slewing the carrier comprises a cylinder and rod assembly, one end of which is pivotally mounted to the carriage and the other end of which is pivotally mounted to the carrier frame. The cylinder conveniently extends through the opening 68 of the pivot mount. The cylinder and rod assembly has a sufficient stroke to slew the carrier through an angle of 90 from a forward facing position to a laterally facing position.

The means 36 for effecting pivotal movement of the lift mast about the pivot points on the front axle housing comprises a hydraulic cylinder and rod assembly, one end of which is pivotally mounted to the body and the opposite end of which is pivotally mounted to one of the intermediate brace members 40. The cylinder rod assembly has a sufficient stroke to provide the lift mast with the required degree of forward and rearward tilt, which will usually be under 10.

In the operation of the lift truck of the invention, a load such as lirnber or the like can be engaged when in the FIG. 1- 2 position by driving the lift forks underneath the load. The ram is then actuated to raise the movable guide and the carriage to elevate the carrier sufficiently high to clear the cab. The cylinder rod assembly 30 then retracts to slew the loaded carrier to its laterally facing position shown in dotted lines in FIGS. 1-2. The ram may then be retracted to lower the caboverlaying lift fork into the cutout roof section such that the load will be lowered on to and supported by the cab roof structure.

When the load is engaged by the forward facing load carrier, the bending forces imposed on the carriage are largely transferred to the lift mast guides by the rearward roller bearing sets 54 and 64. When the load carrier is slewed to its laterally facing position, bending movement forces, imposed on the carriage are largely transferred to the lift mast guides by the forward roller bearing sets 52 and 62. During the horizontal slewing of the load carrier, both the above-mentioned forward and rearward roller bearing sets experience bending movement forces.

In the event that it is desired to stabilize the load by clamping down on it when it is positioned as shown in dotted line in FIG. 2, a hydraulic clamp arm assembly 82 may be mounted along one side of the body and generally in line with and rear ward of the lift mast fixed guide as shown in FIGS. 1, 2 and 4. This assembly comprises an upright arm casing in which a generally L-shaped clamp arm is telescopically positioned, the clamping section of the arm being extended laterally toward the opposite side of the body. A preferred load clamp assembly is shown in FIGS. 5 and 6 carried by the carrier frame 70. By mounting the clamp assembly to the carrier frame, the load may be stabilized during lifting and slewing in addition to stabilizing the load after it has been slewed to a transport position. The FIGS. 1, 2 and 4 embodiment of clamp assembly 82 cannot function to stabilize the load until the load is slewed to the dotted line position shown in FIG. 2.

The preferred clamp assembly 91 comprises a clamp lever arm 93 pivotally hinged to the carrier frame 70 at 95 for movement parallel to the plane of the carrier frame. A clamp mounting arm 97 is fixedly secured to the outer end of the lever arm 93 and extends outwardly therefrom and terminates in a depending bracket 99. The clamp comprises an elongated mounting bracket 101 pivotally hinged to bracket 99 and extending generally perpendicular to the plane of the carrier frame, and an elongated, thick walled tube 103 secured to the base of bracket 101 by bolts or other suitable means. A hydraulic cylinder assembly 105 is pivotally connected at one end to the carrier frame 70 and pivotally connected at the other end to lever arm 93. By this arrangement, the extension and retraction of the cylinder assembly 105 will effect vertical movement of the clamp to accommodate loads of varying height. Tube 103 is fabricated from material having sufficient flexibility to mold itself to the surface confirmation of the load and also having sufficient stiffness to transmit adequate load bearing forces to hold the load.

In the FIGS. 5 and 6 embodiment, the carrier frame 70 is provided with upstanding extension side members 107 and 109 to provide additional support for tall loads. As shown, lever arm 93 and cylinder assembly 105 are pivotally secured to one of these extensions.

To minimize overloading the load carrier pivot mount, a triangular bumper plate 33 is vertically positioned at the left end of the crossbeam 32. The vertical forward edge of the bumper plate contacts the back of the load carrier frame when the latter is being loaded. Appropriate contact members may be located on the back of the frame for contact by the plate 33.

It is believed that the invention will have been clearly understood from the foregoing detailed description of my now preferred illustrated embodiment. Changes in the details of construction may be resorted to without departing from the spirit of the invention and it is accordingly my intention that no limitations be implied and that the hereto annexed claims be given the broadest interpretation to which the employed language fairly admits.

We claim:

1. A lift truck which comprises a body;

forward and rearward wheel assemblies on which said body is carried;

and a lift mast comprising first guide means mounted on said body in a plane generally parallel with the vertical plane containing the longitudinal axis of said lift truck and fixed against vertical reciprocatory movement and against horizontal slewing movement, movable second guide means retained and vertically guided by said first guide means for vertical reciprocatory movement, load carrier means mounted to said movable guide means for vertical reciprocatory movement and adapted to be horizontally slewed, means for effecting vertical reciprocatory movement of said movable guide means and of said load carrier means, and means for horizontally slewing said load carrier means relative to said first and second guide means; and a load clamp assembly mounted on said load carrier means for movement therewith which comprises a clamp member extending outwardly from said load carrier means and clamp-mounting means adjustably mounting said clamp member on said load-carrier means for vertical adjustment relative to said load-carrier means.

2. The lift truck of claim 1 wherein said load clamp-mounting means includes a clamp lever arm pivotally hinged near one side of said load-carrier means and extending generally parallel to the front to rear axis of said carrier,

a clamp-mounting arm secured to the outer end of said clamp lever arm and extending substantially perpendicular to said lever arm,

and hydraulic motor means mounted on said load-carrier means and operatively connected to effect vertical movement of said clamp member.

3. In the lift truck of claim 1 wherein said clamp member comprises an elongated tube pivotally mounted to said clamp mounting arm and fabricated from material having sufficient flexibility to mold itself to the surface conformation of the load and also having sufficient stifiness to transmit adequate load-bearing forces to hold the load.

4. The lift truck of claim 2 wherein said load-carrier means includes a pair of lift forks and a pair of generally horizontal cross rods, each lift fork being suspended by one crossrod and being slidably adjustable therein; and including a pair of lift fork-adjusting means, each such means comprising a fork shift member, pivotally hinged at one end to a stationery part of said load-carrier means and coupled at the opposite end to one of said lift forks, and activating means mounted at one end on a stationery part of said load-carrier means and coupled at the opposite end to said fork shifter member to effect lateral shifting movement of said lift fork on said crossrod through pivotal movement of said fork shifter member.

Claims (4)

1. A lift truck which comprises a body; forward and rearward wheel assemblies on which said body is carried; and a lift mast comprising first guide means mounted on said body in a plane generally parallel with the vertical plane containing the longitudinal axis of said lift truck and fixed against vertical reciprocatory movement and against horizontal slewing movement, movable second guide mEans retained and vertically guided by said first guide means for vertical reciprocatory movement, load carrier means mounted to said movable guide means for vertical reciprocatory movement and adapted to be horizontally slewed, means for effecting vertical reciprocatory movement of said movable guide means and of said load carrier means, and means for horizontally slewing said load carrier means relative to said first and second guide means; and a load clamp assembly mounted on said load carrier means for movement therewith which comprises a clamp member extending outwardly from said load carrier means and clampmounting means adjustably mounting said clamp member on said load-carrier means for vertical adjustment relative to said load-carrier means.

2. The lift truck of claim 1 wherein said load clamp-mounting means includes a clamp lever arm pivotally hinged near one side of said load-carrier means and extending generally parallel to the front to rear axis of said carrier, a clamp-mounting arm secured to the outer end of said clamp lever arm and extending substantially perpendicular to said lever arm, and hydraulic motor means mounted on said load-carrier means and operatively connected to effect vertical movement of said clamp member.

3. In the lift truck of claim 1 wherein said clamp member comprises an elongated tube pivotally mounted to said clamp mounting arm and fabricated from material having sufficient flexibility to mold itself to the surface conformation of the load and also having sufficient stiffness to transmit adequate load-bearing forces to hold the load.

4. The lift truck of claim 2 wherein said load-carrier means includes a pair of lift forks and a pair of generally horizontal cross rods, each lift fork being suspended by one crossrod and being slidably adjustable thereon; and including a pair of lift fork-adjusting means, each such means comprising a fork shift member pivotally hinged at one end to a stationery part of said load-carrier means and coupled at the opposite end to one of said lift forks, and activating means mounted at one end on a stationery part of said load-carrier means and coupled at the opposite end to said fork shifter member to effect lateral shifting movement of said lift fork on said crossrod through pivotal movement of said fork shifter member.

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