GB2081196A

GB2081196A - Forklift Truck Having Improved Drive

Info

Publication number: GB2081196A
Application number: GB8123172A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-08-01
Filing date: 1981-07-28
Publication date: 1982-02-17
Also published as: IT8123262A0; IT1138904B; DE3129676A1; IL60722A0; GB2081196B; IL60722A

Abstract

A forklift truck includes a chassis (2) carrying a vertically-movable forklift (14) at its front end and is driven by a separate hydraulic or electric drive motor (20,24) for each of its two front drive wheels (4,6), the separate drive motors (20,24) each being mounted to the chassis (2) to extend externally and laterally of the chassis. Each drive motor (20,24) is coupled to its respective drive wheel (4,6) by a chain-and-sprocket transmission (22,26) extending internally within the chassis (2) and axially thereof. <IMAGE>

Description

SPECIFICATION Forklift Truck Having Improved Drive The present invention relates to forklift trucks, and particularly to an improved drive construction for forklift trucks.

One common type of forklift truck includes an internal combustion engine drive, such as a diesel engine, directly coupled to the front drive wheels of the truck via a mechanical transmission. Other types include electric motor drives and hydraulic motor drives. More recently, a forklift truck has been developed providing a separate hydraulic motor for each of the front drive wheels of the truck, the two hydraulic motors being fixed within the chassis at its front end in alignment with and directly coupled to, the front drive wheels: An object of the present invention is to provide a forklift truck most similar to the latter type but having a number of advantages over the latter type, as will be described more particularly below.

According to a broad aspect of the present invention, there is provided a forklift truck including a chassis carrying a vertically-movable forklift at its front end and driven by a separate drive motor for each of its two front drive wheels, characterized in that said separate drive motors are each mounted to said chassis to extend externally and laterally thereof, and are coupled to their respective drive wheels by a transmission extending internally within the chassis and axially thereof.

In the preferred embodiment of the invention described below, the front end of the chassis is reduced in width to accommodate the two drive motors such that the outer faces of the drive motors are substantially flush with the central section of the chassis. In addition, in this described embodiment, the outer faces of the drive motors are also substantially flush with the outer faces of the front drive wheels.

In the described preferred embodiment, the two separate motors are hydraulic motors and are both supplied with pressurized hydraulic fluid by a single hydraulic pump mounted to the chassis. It is contemplated, however, that the two separate motors could be electric motors driven by a common battery supply mounted to the chassis.

Also in the described preferred embodiment, the transmission coupling each motor to its respective drive wheel is a chain and sprocket transmission including a eprocket connected to the respective motor by a first shaft extending through the chassis, a second sprocket connected to its respective drive wheel by a second shaft extending through the chassis, and a chain disposed along the inner face of the chassis and coupling the two sprocket wheels together.

Forklift trucks constructed in accordance with the foregoing features provide a number of important advantages. One advantage is that the drive motors are better protected from the severe strains on the drive by the frequent starting, stopping and reversing of the forklift truck since these strains are imposed mostly on the transmission, which can be more conveniently and less expensively repaired than the drive motors themselves. A further advantage is that by virtue of mounting the separate drive motors externally and laterally of the chassis, this enables the length of the chassis, and therefore, the length of the overall forklift truck, to be substantially reduced. At the same time, this novel arrangement provides more room for the parts of the truck drive, which substantially increases the accessibility of the parts for repair and maintenance purposes.It also permits the use of rigid tubes, instead of flexible tubes, for making the hydraulic connections, which further reduces the maintenance problems.

Further features and advantages of the invention will be apparent from the description below.

The invention as herein described, by way of example only, with reference to the accompanying drawings, wherein: Fig. 1 is a top plan view schematically illustrating one form of forklift truck constructed in accordance with the invention; Fig. 2 is an enlarged fragmentary view of a portion of Fig. 1 particularly illustrating the chainand-sprocket transmission between each of the two motors and its respective drive wheel (the chain being omitted in the transmission coupled to the right motor), and Fig. 3 is a side elevational view illustrating the mounting of one of the motors to facilitate adjustment with respect to its chain-and-sprocket transmission.

The forklift truck illustrated in Fig. 1 comprises a chassis, generally designated 2, mounted on a pair of front drive wheels 4, 6, and a pair of rear wheels 8, 10. To the front end of the chassis 2 is secured a mast 1 2 which supports a vertically movable forklift 14. The selector controls 1 6 are in the driver's compartment at the front end of the truck. A counterweight (not shown) is secured to the rear end of chassis 2.

Insofar as described above, the forklift truck illustrated in Fig. 1 may be of any conventional construction, and therefore further details of its structure, particularly of the mast 12, forklift 14, and selector controls 1 6, are not included herein.

In accordance with the present invention, the front section 2a and rear section 2c of the chassis 2 are reduced in width compared to the central section 2b. This reduction in the width of the chassis front section 2a is used for accommodating a drive motor for each of the two front wheels 4, 6. These drive motors extend externally and laterally of the chassis and are coupled to their respective drive wheels 4, 6, by transmissions extending internally within the chassis.

Thus, as shown in Fig. 1, drive motor 20 is mounted externally and laterally of front section 2a of the chassis and is coupled to its respective drive wheel 4 by a transmission, generally designated 22, extending internally within the chassis and axially thereof. Similarly, drive motor 24 is mounted externally and laterally of section 2a of the chassis and is coupled to its respective drive wheel 6 by a transmission 26 extending internally and axially within the chassis.

Motors 20, 24 are hydraulic motors and are supplied with pressurized hydraulic fluid by means of a common hydraulic pump 30 mounted centrally of the chassis front section 2a substantially in alignment with the two motors.

Pump 30 is in turn driven by an internal combustion engine 32, for example a diesel engine, mounted centrally of the rear portion of the chassis. Engine 32 is straddled on one side by a fuel tank 34, and on the opposite side by a hvdraulic-fluid tank 36.

Fig. 2 better illustrates the transmission connecting each of the drive motors 20, 24, to its respective drive wheel 4, 6. Both of these transmissions 22,26, are of the chain-andsprocket type, the chain in the right transmission 26 of Fig. 2 being omitted to better illustrate the sprocket wheels. Thus, each of the two transmissions 22, 26 includes a smaller sprocket wheel 40 disposed internally within the chassis section 2a and coupled to its respective drive motor 20, 24 externally of the chassis by a shaft 42 passing through the chassis wall. The transmission further includes a larger sprocket wheel 44 also extending within the chassis section 2a and connected to its respective drive wheel 4,6 externally of the chassis by means of another shaft 46 extending through the chassis wall.The two sprocket wheels 40 and 44 of each transmission are coupled together by a chain 48 extending internally and axially adjacent to the inner face of the front chassis section 2a.

As shown particularly in Fig. 3, each of the two drive motors 20, 24 is externally mounted to chassis section 2a by a plurality of bolts 50 passing through slots 52 in a mounting plate 54 carried by the motor. The motor shaft 42 (Fig. 2) is passed through the wall of chassis section 2a, and its respective sprocket wheel 42 is mounted internally within the chassis. The slots 52 receiving the mounting bolts 50 are elongated in the axial direction to permit adjustment of the motor, including its sprocket, so as to enabie the chain 48 to be properly applied around the drive motor sprocket 40 and the drive wheel sprocket 48.

The connections from the common pump 30 to the two drive motors 20, 24 may be done by rigid tubes 56 (Fig. 1), since the described arrangement provides ample room enabling the use of rigid tubes.

It will thus be seen that the externally-mounted drive motors 20, 24 are readily accessible for repair and maintenance purposes. Preferably, the outer faces of the drive motors 20, 24 are substantially flush with the middle section 2b of the chassis, and also with the outer faces of the two front drive wheels 4, 6. The outer face of the middle chassis section 2c may also be substantially flush with the outer faces of the rear wheels 8, 10 on the rear chassis section 2c.

This arrangement provides very convenient accessibility not only to the drive motors 20, 24j but also to the other elements of the drive system, particularly the pump 30, engine 32, and the connections between them and the drive motors 20, 24, which greatly facilitates the repair, maintenance and replacement of these parts. The described arrangement also enables a substantial reduction in the truck length to be made, for example, from about 2.5 meters to about 2.0 2.2 meters.

A further important advantage in the described arrangement is that the transmissions 22, 26, coupling the two drive motors 20, 24 to their respective drive wheels 4, 6, take-up most of the strain resulting from the frequent starting, stopping, and reversing of the forklift truck. Thus, the strain is directed to the transmission mechanism 22, 26, which can be serviced and repaired more conveniently and less expensively than the drive motors 20, 24.

While the invention has been described with respect to one preferred embodiment, it will be appreciated that many variations, modifications, and applications of the invention may be made.

Claims

1. A forklift truck including a chassis carrying a vertically-movable forklift at its front end and driven by a separate drive motor for each of its two front drive wheels, wherein said separate drive motors are each mounted to said chassis to extend externally and laterally thereof, and are coupled to their respective drive wheels by a transmission extending internally within the chassis and axially thereof.

2. A forklift truck according to Claim 1, wherein the front end of said chassis is reduced in width to accommodate the two drive motors such that the outer faces of the drive motors are substantially flush with the central section of the chassis.

3. A forklift truck according to Claim 1 or 2, wherein the outer faces of the drive motors are substantially flush with the outer faces of the front drive wheels.

4. A forklift truck according to any one of Claims 1-3, wherein said drive motors are A hydraulic motors and are both supplied with pressurized hydraulic fluid by a single hydraulic pump mounted within said chassis.

5. A forklift trUck according to Claim 4, wherein said common hydraulic pump is driven by an internal combustion engine also mounted within said chassis.

6. A forklift truck according to Claim 5, wherein said internal combustion engine is mounted centrally of said chassis and is straddled on one side by a fuel tank mounted on the chassis, and on the opposite side by a hydraulic oil tank also mounted on the chassis.

7. A forklift truck according to Claim 5 or 6, wherein said common hydraulic pump is mounted on the chassis forwardly of the internal combustion engine and in substantial alignment with the two hydraulic motors mounted externally of the chassis.

8. A forklift truck according to any one of Claims 1-7, wherein said transmission coupling each motor to its respective drive wheel is a chain-and-sprocket transmission including a sprocket connected to the respective motor by a first shaft extending through the chassis, a second sprocket connected to its respective drive wheel by a second shaft extending through the chassis, and a chain disposed along the inner face of the chassis and coupling the two sprocket wheels together.

9. A forklift truck according to Claim 8, wherein said motors and their respective sprockets are mounted externally of the chassis by mounting bolts received in elongated slots in the chassis to permit adjustment of the motors and their sprockets with respect to the chain coupling the latter sprockets to the sprockets of the drive wheels.

10. A forklift truck substantially as described with reference to and as illustrated in the accompanying drawings.