WO1998045134A1

WO1998045134A1 - Crawler drive

Info

Publication number: WO1998045134A1
Application number: PCT/AU1998/000231
Authority: WO
Inventors: William Arthur Haire; Keith Alistair Haire
Original assignee: William Arthur Haire; Keith Alistair Haire
Priority date: 1997-04-04
Filing date: 1998-04-06
Publication date: 1998-10-15
Also published as: AUPO602497A0

Abstract

A crawler drive for use in conjunction with a vehicle (10) to enable it to work at relatively low speeds but with high engine revolutions, the crawler drive including a gear box (28) for attachment to the transmission (26) output of the vehicle (10), a clutch assembly (38) for attachment to the gear box (28) so as to be able to drive at least one drive shaft (18) of the vehicle (10) to enable the vehicle (10) to move, the gear box (28) being able to be powered independently of the transmission (26) of the vehicle (10).

Description

CRAWLER DRIVE

Field of the invention

This invention relates to crawler drives and refers particularly, though not exclusively, to crawler drives for use with self-propelled vehicles such as, for example, wheel loaders, which are normally not capable of slow operational speeds.

Background of the invention

Many self-propelled vehicles are intended to be used at relatively low speeds to perform certain tasks. For example, snow ploughs and snow blowers move at relatively slow speed so that the road can be cleared of snow. Road profilers work at slow speed so that the profiler mechanism will be able to operate to provide the necessary road profiling. Furthermore, the devices such as graders are used at relatively slow speed to enable the blade to be able to perform the necessary work task.

Many machines such as front-end loaders, wheel loaders, and so forth are not normally capable of working at those slow speeds due to the inherent nature of their design and/or operation. This therefore requires, in many instances, two pieces of large equipment to be able to perform the necessary tasks. With such equipment costing several hundreds of thousands of dollars, the cost to the purchaser and user is quite significant.

It is therefore the object of the present invention to provide a crawler drive for use with vehicles which will enable them to move at relatively low speeds to be able to perform the task, and to allow the vehicle engine to provide sufficient revolutions to enable hydraulic systems to operate at full effectiveness.

Brief description of the invention

With the above and other objects in mind the present invention provides a crawler drive for use in conjunction with a vehicle to enable it to work at relatively low speeds but with high engine revolutions, the crawler drive including a gear box for attachment to the transmission output of a vehicle, a clutch assembly for attachment to the gear box so as to be able to drive at least one drive shaft of the vehicle to enable the vehicle to move, the gear box being able to be powered independently of the transmission of the vehicle.

Preferably, there is provided an auxiliary source of power, independent of the gear box or transmission, for the operation of a mechanism to be used with the vehicle. Advantageously, the gear box is attached to the transmission. Alternatively, the gear box may be remote from the transmission.

Brief description of the drawings

The invention will now be described by way of non-limitative example only and with reference to the accompanying illustrative drawings in which:

Figure 1 is a schematic side view of a crawler drive as fitted to a conventional wheel loader; and

Figure 2 is a view corresponding to Figure 1 without an alternative embodiment of a crawler drive. Description of the preferred embodiment

To refer to Figure 1, there is shown a wheeled loader generally designated as 10 which has rear wheels 12 driven by a rear drive shaft 14, and front wheels 16 driven by a front drive shaft 18. Hydraulically operated arms 20 and a work piece 22 (also hydraulically operated) are provided. An engine 24 operating through a transmission 26 provides for appropriate power and drive to the loader 10.

With the present invention the front drive shaft 18 is interrupted and a gear box 28 is placed in-line. This means that the early portion 30 of the drive shaft 18 is connected to the gear box 28, as is the later portion 32. The gear box 28 is adapted to be driven by a motor 34 which is preferably a hydraulic motor driven by a hydraulic pump 36 which is adapted to be driven by engine 24 and transmission 26. The hydraulic connection is not shown although standard hydraulic connections can be used. A clutch 38 is provided so that the gear box 28 can be engaged and disengaged with the drive shaft 18.

It is preferred that the crawler drive gear box 28 is a planetary gear set with the ring gear being connected to the output shaft by splines. It is driven through the sun gear with the carrier gear being held.

To operate the wheel loader using the crawler drive, the standard transmission 26 is placed in neutral and the clutch 38 engaged. With the engine 24 operating at high revolutions, hydraulic fluid under high pressure is supplied by pump 36 to motor 34. This then drives gear box 28 to thus drive front and rear portions 30,32 of drive shaft 18, which are interconnected through gear box 28. Drive shaft 14 is also driven due to its interconnection through transmission 26. In this way, the front wheels 16 as well as the rear wheels 12 are able to be driven.

In this way the loader 10 can move at relatively low speeds - much lower than those which would normally be possible. In this way the work piece 22 may be replaced by an appropriate other workpiece which requires low operational speeds. Good examples are road profilers, which are a toothed drum, which could be driven by the hydraulic drive such as the hydraulic pump 40 which would be able to power the road profiler. Alternatively, it could be a snow blower or any other suitable device to operate loader 10 normally, the clutch 38 is disengaged so that transmission 26 can then drive both drive shafts 14, 18 to drive wheels 12, 16.

In Figure 2 there is shown a variation with the prefix number 2 being placed before like components. Again, there is a wheeled loader 210 with rear wheels 212 being driven by a rear drive shaft 214. Front wheels 216 are driven by a front drive shaft 218. Arms 220 are hydraulically operated to control the operation of a workpiece 222, which is also hydraulically operated. An engine 224 is used to provide appropriate power to the wheels 212, 216 via a transmission 226. The pumps 236 and 240 operate as in the past, as does the crawler drive gear box 228. In this instance, however, the gearbox 228 is directly mounted to the output portion of the transmission 226 so that it directly derives the front drive shaft 218. The hydraulic motor 234 is therefore mounted on the front of the gear box 228 rather than the top, for clearance purposes. In all other respects, the operation is the same as for the embodiment of Figure 1. In both instances, the motor 34, 234 may be an axial piston motor or any other suitable form of hydraulic motor. The gear box 28, 228 has been described earlier. Such gear boxes may be gear boxes as known under the registered trade mark "REYNOLD". Whilst the invention has been described with reference wheel loaders, it may be used with other mechanisms which are self propelled and which require the ability to provide low- speed drive in addition to the normal drive used. The advantage of the system described is that it allows great control over the low speed by virtue of the hydraulic nature of the drive. Gradual implementation can be used and progressive increase to speed. By having the engine 24, 224 at high revolutions, full hydraulic pressure is available to not only the motor 34, 234 but also all of the hydraulically operated systems and mechanisms which may be used with or as part of loader 10. Whilst there has been described in the foregoing description preferred embodiments of a crawler drive, it will be understood by those skilled and the technology concerned and many variations or modifications in details of design or construction may be made without departing from the essence of the present invention. It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

It will also be understood that where the term "comprises" or its grammatical variants, is employed herein, it is equivalent to the term "includes" and is not to be taken as excluding the presence of other elements or features.

Claims

The claims defining the invention are as follows:

1. A crawler drive for use in conjunction with a vehicle to enable it to work at relatively low speeds but with high engine revolutions, the crawler drive including a gear box for attachment to the transmission output of the vehicle, a clutch assembly for attachment to the gear box so as to be able to drive at least one drive shaft of the vehicle to enable the vehicle to move, the gear box being able to be powered independently of the transmission of the vehicle.

2. A crawler drive as claimed in claim 1, wherein there is an auxiliary source of power, independent of the gear box or transmission, for the operation of a mechanism to be used with the vehicle.

3. A crawler drive as claimed in claim 1 or claim 2, wherein the gear box is attached to the transmission.

4. A crawler drive as claimed in claim 1 or claim 2, wherein the gear box is remote from the transmission.

5. A crawler drive as claimed in anyone of claims 1 to 4, wherein there is provided a motor to drive the gear box.

6. A crawler drive as claimed in claim 5, wherein the motor is an hydraulic motor.

7. A crawler drive as claimed in claim 6, wherein the motor is adapted to be driven by an engine of the vehicle acting through the transmission.

8. A crawler drive as claimed in any one of claims 1 to 7, wherein the clutch assembly selectively engages and disengages the gear box with and from the at least one drive shaft.

9. A crawler drive substantially as hereinbefore described with reference to the accompanying drawings.