GB2125744A

GB2125744A - A road and rail tractor

Info

Publication number: GB2125744A
Application number: GB08320056A
Authority: GB
Inventors: Thomas Coleman; Manus Coffey; Norman Slack
Original assignee: SLOCUM Ltd
Current assignee: SLOCUM Ltd
Priority date: 1982-08-12
Filing date: 1983-07-26
Publication date: 1984-03-14
Also published as: GB8320056D0; IE821947L; BE897506A; IE53584B1

Abstract

The tractor comprises a chassis (2) a pair of front and rear rail engaging wheels (4) and a pair of front and rear ground engaging wheels (8). The wheels (8) are retractable by hydraulic rams and on lowering raise the wheels (4) and (5) off the rails. The front wheels (8) are steerable. An engine (10) drives the wheels (4) and the road rear wheels through a gearbox, a differential unit and chains and sprockets. A turntable plate (52) when lowered raises the tractor completely so that it may be turned, e.g. through 90 DEG to allow the tractor to be driven from the rails using the road wheels. <IMAGE>

Description

SPECIFICATION Road and rail tractor The present invention relates to a road and rail tractor primarily for spotting railway vehicles in railway goods yards, which is operable on or off rails.

Such tractors are known and are described in U.S. Patent Specifications Nos. 3356042, 3399633 and 3709153. However, these tractors suffer from certain disadvantages in that difficulty sometimes is experienced when transferring the vehicle to and from the rails.

There is therefore a need for a tractor which overcomes these problems.

The present invention is directed towards providing such a tractor.

According to the invention, there is provided a road and rail tractor comprising rail engaging wheels and at least three ground engaging wheels, either the ground engaging wheels and/or the rail engaging wheels being retractable. Preferably, the ground engaging wheels are retractable.

Advantageously, two pairs of ground engaging wheels are provided, one pair adjacent the front of the tractor and the other pair adjacent the rear, at least one of said pairs of wheels being steerable.

In one embodiment of the invention the front pair of ground engaging wheels are steerable and are mounted on a steering frame being retractable by a hydraulic ram.

In another embodiment of the invention the rear pair of ground engaging wheels are each mounted on an independent trailing arm and means to raise the trailing arms are provided to retract the wheels.

In a further embodiment of the invention motor means to power the ground engaging wheels and the rail engaging wheels are provided. The ground engaging wheels being driven through clutch means.

The invention will be more clearly understood from the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings in which: Figure 1 is a side elevational view of a tractor according to the invention, Figure 2 is a front elevational view of the tractor of Fig. 1, Figure 3 is the plan view of the tractor of Fig. 1, and Figure 4 is a side view of a detail of the tractor of Fig. 1.

Referring to the drawings there is provided a road and rail tractor according to the invention indicated generally by the reference numeral 1. The tractor 1 comprises a chassis 2 on which is mounted a drivers cab 3. Front and rear pairs of rail engaging wheels 4 and 5 respectively are rotatable on stub axles 6, which are in turn rotatable in bearings 7 mounted on the chassis 2. Front and rear pairs of ground engaging wheels 8 and 9 respectively with pneumatic tyres 39 are also provided adjacent the front and rear of the tractor 1. Both the rear and front rail engaging wheels 4 and 5 and the rear ground engaging wheels 9 are driven by an engine 10 mounted on the chassis. This is described in more detail below.

A framework 50 also mounted on the chassis 2 supports a lift footing indicated generally by the reference numeral 51 for lifting the tractor clear of the ground and the tracks.

The lift footing 51 is mounted substantially at the centre of gravity of the tractor and comprises a turn foot 52 on a spindle 53 for rotating the tractor. The spindle 53 and turn foot 52 are extendable by a hydraulic ram 54 mounted on the framework 50.

The invention is directed towards the ground engaging wheels support mechanisms and accordingiy, only these and the drive transmission will be described in detail in the Specification. The other components of the tractor are illustrated diagramatically and will be readily clear to those skilled in the art.

The front pair of ground engaging wheels 8 are steerable and are mounted on a steering frame 11. Hydraulic rams 1 2 rise and lower the steering frame 11. The rams 1 2 are mounted on a support frame 1 3 which is in turn mounted on the chassis 2. A steering mechanism (not shown) operated by a steering wheel (also not shown) mounted in the cab 3 steers the wheels 8. Such steering mechanisms will be well known to those skilled in the art.

The rear pair of ground engaging wheels 9 are mounted on two independent trailing arms 14. Each arm 14 is pivotally mounted on an intermediate drive shaft 1 6 by a bearing 15.

The intermediate drive shaft 1 6 is rotatable in bearings 36 mounted on the chassis 2. The shaft 1 6 is described in detail below. A stub axle 1 7 mounted on each trailing arm 14 rotatably supports a ground engaging wheel 9. The wheels 9 are rectractable by hydraulic rams 1 9 which raise and lower the trailing arms 1 2. Each hydraulic ram 1 9 is pivotally mounted on a support 20 by a bracket 21.

The supports 20 are rigidly mounted on each side of the chassis 2. A bracket 22 on each trailing arm 1 4 pivotally engages a piston rod 23 of each ram 19.

The engine 10 drives the rear ground engaging wheels 9 and the front and rear rail engaging wheels 4 and 5 through a gear box 24 and differential drive unit 25. Sprockets 26 mounted at the ends of half-shafts 1 8 from the differential unit 25 drive the intermediate drive shafts 1 6 through a chain 27 and sprockets 28 fast on the drive shaft 16.

Sprockets 29 fast on the intermediate drive shaft 1 6 drive the front and rear rail engaging wheels through chains 30 and sprockets 31 fast on the stub shafts 6. Sprockets 32 fast on the rear ground engaging wheels 9 are driven through a chain 33 by a sprocket 34.

Each sprocket 34 is mounted on clutch means, in this case a dog clutch 35 mounted on the shaft 1 6 to permit drive to be disconnected from the ground engaging wheels when they are not in use in the retracted positions.

Control apparatus (not shown) to operate the rams 1 2 and 1 9 and also the dog clutch 35 is provided in the cab 3. Conventional motor control levers and foot-pedals (not shown) are also provided in the cab 3.

In use, the road and rail tractor 1 is operated on rails with the front and rear ground engaging wheels in the retracted position as illustrated in Fig. 2. When it is desired to drive the tractor 1 off the rails 40 the turn foot 52 is lowered by the hydraulic ram 54.

This raises the tractor off the rails, and the tractor may then be pivoted through 90 transverse of the rails. The ground engaging wheels 8 and 9 are lowered by the hydraulic rams 1 2 and 1 9 to the position illustrated in Fig. 1. and the turn foot 52 is retracted, thereby lowering the tractor onto the ground engaging wheels 8 and 9. The drive is then transferred from the rail engaging wheels 4 and 5 to the ground engaging wheels 8 and 9 by means of the dog clutch 35. The tractor may then be driven off the rails and over ground or rough terrain as desired.

It will be appreciated that although the invention has been described with particular arrangements of front and rear ground engaging wheels, other suitable arrangements of wheels may be provided. It will be appreciated that either the front or rear ground engaging wheels could be steerable. Indeed, in certain cases it will be appreciated that only three ground engaging wheels would be required. Where three ground engaging wheels are provided, it is envisaged that the single wheel would be mounted to the front or rear and would be steerable while the other two wheels would be mounted at the alternate end. It will also be appreciated that if desired all the ground engaging wheels could be driven. Additionally, if desired, many more than four ground engaging wheels could be provided.

Furthermore, it will be appreciated that means for raising and lowering the ground engaging wheels other than hydraulic rams could be provided. For example, pneumatic rams or indeed, servo-motors. Additionally, it will be appreciated that it is not necessary for the rear ground engaging wheels to be mounted on a trailing arm. They could be mounted on any other suitable arrangement, for example a bogey.

It is envisaged that instead of driving the ground engaging wheels through a dog clutch, other suitable means could be used for isolating drive from the ground engaging wheels.

It will also be appreciated that it is not necessary for all four rail engaging wheels to be driven. In certain cases, only the two rear or front wheels may be driven if desired.

Furthermore, it will be appreciated that while in the embodiment of the invention just described, the ground engaging wheels have been described as being retractable, this is not necessary. If desired, the rail engaging wheels could have been made retractable, and/or the ground engaging wheels could be retractable. Additionally, it will be appreciated that while a certain drive arrangement has been described to drive the rail and ground engaging wheels, any other suitable drive arrangement could be used.

It is envisaged that in certain cases a drive mechanism could be provided to rotate the tractor on the turn footing 51. Such arrangements will be well known to those skilled in the art. Indeed, it will be appreciated that although the tractor has been described as comprising a turn footing for rotating the tractor, this could be dispensed with if desired, in which case, the tractor would be driven directly off the rails by means of the ground engaging wheels.

Claims

1. A road and rail tractor comprising rail engaging wheels and at least three ground engaging wheels, either the ground engaging wheels and/or the rail engaging wheels being retractable.

2. A road and rail tractor as claimed in Claim 1 in which the ground engaging wheels are retractable, and lowerable to engage the ground to a position to raise the rail engaging wheels.

3. A road and rail tractor as claimed in Claims I or 2 in which two pairs of ground engaging wheels are provided, one pair adjacent the front of the tractor and the other pair adjacent the rear, at least one of said pairs of wheels being steerable.

4. A road and rail tractor as claimed in Claim 3 in which the front pair of ground engaging wheels are steerable and are mounted on a steering frame being retractable by a hyraulic ram.

5. A road and rail tractor as claimed in any preceding claim in which the rear pair of ground engaging wheels are each mounted on an independent trailing arm and means to raise the trailing arm are provided to retract the wheels.

6. A road and rail tractor as claimed in Claim 5 in which the means to raise each trailing arm is a hydraulic ram.

7. A road and rail tractor as claimed in any preceding claim in which motor means to power the ground engaging wheels and the rail engaging wheels are provided. The ground engaging wheels being driven through clutch means.

8. A road and rail tractor as claimed in Claim 7 in which the motor means drives the rear ground and rail engaging wheels through a common differential drive unit, the drive being delivered from the differential drive unit by drive means at each side of the differential unit.

9. A road and rail tractor as claimed in Claim 8 in which the front rail engaging wheels are driven.

10. A road and rail tractor as claimed in Claims 8 or 9 in which each drive means is provided by an intermediate drive shaft on each side of the differential unit, driven by chain and sprocket drives from the differential drive unit, the drive being delivered from the intermediate drive shaft to the wheels by further chain and sprocket drives, the clutch means being mounted on the intermediate drive shaft just before the sprocket drive to each ground engaging wheel.

11. A road and rail vehicle substantially as described herein with reference to and as illustrated in the accompanying drawings.