US3894616A

US3894616A - Forklift

Info

Publication number: US3894616A
Application number: US381438A
Authority: US
Inventors: Kunihisa Kawanishi; Shuji Ohta; Seigo Shimizu
Original assignee: Toyoda Automatic Loom Works Ltd
Current assignee: Toyota Industries Corp
Priority date: 1972-07-25
Filing date: 1973-07-23
Publication date: 1975-07-15
Anticipated expiration: 1992-07-15
Also published as: JPS5326384B2; JPS4931053A; DE2335287A1

Abstract

The hydraulic conduits which operate an attachment on the carriage of a forklift pass vertically up in back of the carriage-lifting ram, then each pass over a pair of sheaves mounted above this ram, then pass down in front of the ram, always lying within the projection of the ram in the normal direction of travel. The sheaves are secured between a pair of brackets carried on the piston rod of the ram, on the extensible uprights within the forklift mass assembly, or on both of these elements. Tie rods adjacent the sheaves in their regions of contact with the conduits prevent these conduits from jumping off the sheaves.

Description

United States Patent Kawanishi et al.

[56] References Cited UNITED STATES PATENTS 2.635.774 4/1953 Backofen et a1 214/653 X 2,763,390 9/1956 Vandcmark 214/653 2.826.323 3/1958 Schenkclberger 214/730 FORKLIFT Inventors:

Assignee:

Filed:

Appl. No.:

Kunihisa Kawanishi, Obu; Shuji Ohta, Toyohashi; Seigo Shimizu, Kagamigahara. all of Japan Toyota Automatic Loom Works, Ltd. Kariya, Japan July 23, 1973 Foreign Application Priority Data Field of Search 187/9, 17; 214/620, DIG. ll, 214/650-65 1. 660, 670-674. 730, 731

1 1 July 15,1975

2.836.317 5/1958 Oury 214/653 2,883,003 4/1959 Arnot 187/9 2.979.162 4/196] Quayle 187/9 3.4Sl,498 12/1969 Sturtz 214/620 Primary ExaminerRichard A. Schacher Assistant E.raminer-.lames L. Rowland Attorney, Agent. or Firm-Karl F. Ross; Herbert Dubno [5 7] ABSTRACT The hydraulic conduits which operate an attachment on the carriage of a forklift pass vertically up in back of the carriage-lifting ram, then each pass over a pair of sheaves mounted above this ram. then pass down in front of the ram, always lying within the projection of the ram in the normal direction of travel. The sheaves are secured between a pair of brackets carried on the piston rod of the ram, on the extensible uprights within the forklift mass assembly, or on both of these elements. Tie rods adjacent the sheaves in their regions of contact with the conduits prevent these con duits from jumping off the sheaves.

1 Claim, 8 Drawing Figures FORKLIFT Field of the Invention The present invention relates to a forklift vehicle and, more particularly, to a fluid conduit arrangement in a forklift truck which supplies pressurized fluid to a fluid-operated attachment which is movable vertically along stationary or movable masts or uprights.

Background of the Invention On the carriage of a lift truck there is frequently mounted an attachment for rotating. clamping or laterally shifting the load. In order to actuate such an attachment, hoses or fluids conduits are provided between the attachment and directional control valves on the body ofthe forklift at a pressure source in the body. These conduits must pass over sheaves sufficiently flexibly while remaining taut to allow the carriage with the attachment to move along the mast assembly of the forklift.

In a conventional arrangement, fluid conduits are reeved over sheaves rotatably mounted on a cross arm attached to an extensible portion of a fluid motor, usually over sheaves mounted outwardly of adjacent sprockets on the same cross arm, where the operator's visibility is much reduced. In another conventional arrangement fluid conduits run along the outside of the mast where they are susceptible to damage, for instance. due to collision. Increase of the number of sheaves over which conduits are reeved. and frequent changing of feed direction as is sometimes inevitable, are apt to increase friction and interfere with operator visibility.

Mounting arrangements for fluid conduits and/or other power-transmitting lines have been developed in various prior systems. In one system, fluid conduits are reeved around several sheaves so that at least one loop is formed to keep the flexible conduits taut. This con siders protection of hoses or the like from the point of view of preventing interference in truck operation because of a tendency for the hoses to be caught in the operating mechanism. However, little attention is directed to the problem of the hoses being damaged by collision, and none at all to the problem of friction.

In another known system, a triple-stage telescopic upright structure affords excellent operator visibility through the structure by a good chain arrangement but does not solve the problem of hose arrangement.

An apparatus is known for reeving conduits in a triple-section extensible mast, especially having a device for compensating for the change in length of the fluid conduits when pressurized fluid is supplied. This improves the operators visibility and prevents damage to the conduit arrangement; however, these improve ments are of only limited effect because a chain arrangement sometimes impairs the operators visibility and the conduits are sometimes arranged on the outsides of the mast members where they are accessible for servicing but liable to be damaged.

In practice it is understood that improvements in operator visibility and protection from damage have been incompatible for fluid conduits of forklift trucks. Moreover, fluid conduits arranged in such a fashion as to change direction repeatedly in order to improve operator visibility will often result in increased friction between the conduits and their sheaves especially when the carriage moves up and down along the uprights.

Objects of the Invention It is therefore an object of the present invention to provide an improved forklift.

Another object is the provision of a forklift having a fluid-operated attachment on the vertically displaceable carriage and improved visibility.

A further object is to provide such a forklift wherein the fluid conduits for the attachment are protected from harm.

Summary of the Invention These objects are attained in the present invention wherein the fluid conduits are arranged close to a plane which is the longitudinal center-line plane of the lift truck and substantially within the longitudinal projection of the lift cylinder. which is substantially a dead zone for operator visibility.

Description of the Drawing The above and other objects, features. and advan tages of the present invention will be more readily understood from the following. reference being made to the accompanying drawing in which:

FIG. I is a perspective view of a lift truck or forklift with the arrangement of fluid conduits according to this invention;

FIG. 2 is an enlarged perspective view of the upper part of FIG. I. showing a typical arrangement of the fluid conduits reeved over a pair of sheaves at the top of an extensible piston rod of a fluid cylinder:

FIG. 3 is a front elevation of FIG. 2; FIG. 4 is a cross section along line IV IV of FIG.

FIG. 5 is a cross section along line V V of FIG. 3;

FIG. 6 is a perspective exploded view of a pair of brackets which accommodate a pair of sheaves. a pair of pins and a pair of bars.

FIG. 7 is a perspective view of a clip for keeping fluid conduits parallel side-by-side; and

FIG. 8 is an enlarged perspective view of another embodiment similar to FIG. 2.

Specific Description FIG. 1 shows a lift truck or forklift of substantially conventional construction having a body portion T, an

operators station S, a mast assembly M comprising stationary uprights I and extensible uprights 3 and a carriage C movable vertically along the mast assembly M.

As shown in FIGS. 2 to 5, the mast assembly M comprises a pair of spaced-apart C-section channels I which are vertical and connected together by a plurality of horizontal cross braces 2 to form a rigid and substantially fixed unitary structure. An inner slide or mast has a pair of spaced-apart generally I-section channels 3 which are vertical and connected together by a plurality of horizontal cross braces 4, the beams 3 being cut-off at one flange.

A fluid cylinder 5 is mounted centrally between the two channels 1 of the mast M parallel thereto and fastened to the mast at the bottom as is known.

An upwardly extensible piston rod 6 of the ram 5 carries on its upper end a cross-arm or a sprocketwheel support 7 which rotatably supports a pair of sprocket-wheels 8 to either side of its support 7. A pair of chains 9 which are fastened at their one ends to a flange 5a integral with the cylinder 5 and at their other ends of the carriage C. pass over the wheels 8.

As seen in FIGS. 3 and 4, between the cross brace 4 at the top of the

inner mast assembly

3, 4 and the sprocket-wheel support 7 there are rigidly mounted a pair of brackets II which are secured therebetween by a pair of bolts 10, washers 10a and nuts 101). Thus ex tension of the ram 5 through a predetermined distance displaces the beams 3 through this distance and the can riage C through twice this distance.

The brackets II, as shown in FIG. 6, are fastened together by tie bars 17 and 18 having nuts 17a and 18a. Between the brackets 11 a pair of sheaves or pulleys 12, I3 are rotatable on horizontal pins 14 and I5 secured in the parallel and spaced brackets II. The sheaves are positioned above the fluid motor 5 and are horizontally spaced apart in the longitudinal direction of the truck that is the normal direction of travel of the truck indicated by arrow A. A plurality of fluid conduits [6 are reeved in parallel over the sheaves l2 and 13. As best shown in FIG. 5, the conduits 16 are disposed to the front and rear of the cylinder 5, substantially within the longitudinal projection of this fluid cylinder where the operators visual angle a is blocked in any case. In this manner the operators visibility is not sacrificed. Such improved visibility for the operator contributes to efficiency and safety of operation. These conduits 16 are inextensible hydraulic hoses which are connected to attachments such as a clamp cylinder on carriage C.

The fluid conduits 16 are banded together in parallel alignment by a clip I9 (shown in FIG. 7) which is made of elastic sheet steel or synthetic resin in such a fashion as to be easily snapped in and out of the three conduits l6 and is able to pass over sheaves of relatively small diameter. The function of the clip I9 is to prevent the conduits from misaligning or moving due to vibration.

The tie bars 17 and I8 not only connect the brackets 11 together but also prevent the conduits I6 from running out of grooves of the sheaves l2 and I3.

The bolts 10 may be utilized as guide bars for the sprocket-wheel support 7 in case free lift" is required. This is achieved by reducing the height of the brackets II, or by adopting the embodiments described below.

The bracket assembly including the sheaves 12. I3 can be mounted on the sprocket-wheel support 7 without any connection with the cross-brace 4 or can be hung from the cross-brace 4 without any connection with the support 7. In either embodiment the fluid conduits are reeved over a plurality of sheaves or pulleys supported above the fluid motor.

As seen from FIG. 4 it will be easily understood that the arrangement of a pair of sheaves 12, I3 spaced apart in the longitudinal direction can reduce or minimize the respective contact-angles 0 of 60 and 6 of I20 between conduits and sheaves, compared with conventional arrangements of fluid conduits, and also enables the conduits each to run in a respective plane parallel to the vertically longitudinal center-line plane P of the truck. i.e.. with minimal change of direction. Such reduced or minimized contact-angles and minimal directional change reduce friction between fluid conduits and contacting guides therefor. such as sheaves.

Further merits of reduced contact-angles are to increase the life of the fluid conduits and to allow utilization of sheaves of smaller diameters which contributes to design freedom as well as to free-lift possibility when necessary.

It is also understood that the fluid-conduit arrangement, concentrated close to the vertically longitudinal center-line plane P, prevents the fluid conduits from being damaged by collision, making it much safer when compared with a conventional arrangement of conduits running on exposed surfaces of the mast. Such an arrangement also prevents interference with the operation of the truck by being caught in the operating mechanism.

Improved visibility in accordance with the present invention allows a lift truck to have a narrower mast structure which is suitable for operation in narrower space.

Another embodiment of the present invention is shown in FIG. 8 where five conduits including two additional conduits are used. Three conduits 16 pass over a pair of sheaves I2, I3 between the brackets ll, 11 and two conduits I6 pass over an additional pair of sheaves 12', I3. rotatably mounted on extensions l4'l5' of the pins 14, 15 respectively. The tie rods 17, I8 are provided with extensions I7, 18 to protect the additional conduits from running out of the sheaves l2, 13', with suitable flanges l7", 18" mounted thereon preventing the extra conduits 16' from slipping offv In conclusion the present invention can provide a lift truck comprising an improved arrangement of fluid conduits which affords better operator visibility, less susceptibility to damage, and less friction.

We claim:

I. A forklift comprising:

a body adapted to travel along the ground in a normal travel direction;

a mast assembly on said body including a pair of relatively fixed uprights and a pair of movable uprights vertically displaceable on said fixed uprights;

a carriage vertically displaceable on said mast assem a fluid ram operatively connected to said carriage and disposed between said uprights, said fluid ram including an extensible piston rod;

a cross-brace fixedly attached to said pair of movable uprights;

a sprocket-wheel support fixedly mounted on said piston rod;

a pair of spaced apart brackets secured to said crossbrace;

a pair of sheaves journaled on said brackets including a forwardly disposed sheave and a rearwardly disposed sheave. at least one of said sheaves lying in the vertical projection of said piston rod and directly over said piston rod while being spaced below said cross-brace;

a pair of fasteners interconnecting said cross-brace and said support:

a fluid operated attachment on said carriage; and

at least two flexible hydraulic conduits connected between said attachment and said body, said conduits being reeved over both of said sheaves and passing through said projection and between said fasteners. said sheaves being positioned to maintain the maxi mum bend of said conduits over either sheave at about

Claims

1. A forklift comprising: a body adapted to travel along the ground in a normal travel direction; a mast assembly on said body including a pair of relatively fixed uprights and a pair of movable uprights vertically displaceable on said fixed uprights; a carriage vertically displaceable on said mast assembly; a fluid ram operatively connected to said carriage and disposed between said uprights, said fluid ram including an extensible piston rod; a cross-brace fixedly attached to said pair of movable uprights; a sprocket-wheel support fixedly mounted on said piston rod; a pair of spaced apart brackets secured to said cross-brace; a pair of sheaves journaled on said brackets including a forwardly disposed sheave and a rearwardly disposed sheave, at least one of said sheaves lying in the vertical projection of said piston rod and directly over said piston rod while being spaced below said cross-brace; a pair of fasteners interconnecting said cross-brace and said support; a fluid operated attachment on said carriage; and at least two flexible hydraulic conduits connected between said attachment and said body, said conduits being reeved over both of said sheaves and passing through said projection and between said fasteners, said sheaves being positioned to maintain the maximum bend of said conduits over either sheave at about 120*.