GB2029783A

GB2029783A - Differential Gears

Info

Publication number: GB2029783A
Application number: GB7922269A
Authority: GB
Original assignee: LEATHERLAND S
Current assignee: LEATHERLAND S
Priority date: 1978-06-26
Filing date: 1979-06-26
Publication date: 1980-03-26

Abstract

In a differential gear for a driven axle for a vehicle, particularly a model racing car, the rotational drives to and from the differential are applied about a common axis. The input drive is by way of a detachable gear wheel 28, and one of two output shafts 24, 25 has secured thereon a cylindrical member 32 which surrounds the differential gear and is adapted to serve as a wheel hub on which a tyre can be mounted between flanges 34. <IMAGE>

Description

SPECIFICATION Improvements relating to Differential Gears The present invention relates to differential gears, particularly for use in model racing cars.

Model racing cars use two types of driven axle, the first being a solid axle and the second being an axle incorporating a differential gear. Axles with differential gears are essential for racing on a winding track since the use of a solid axle reduces the grip of the driven wheels on the track and increases any tendency to slide or spin off the track. Axles with differentials, however, suffer from the disadvantage that they make it very difficult to remove and repiace road wheels and axles during a race. The body of the car has to be partially dismantled to allow the road wheels, axle and differential gear to be lifted out of the car. In contrast with this the removal of a road wheel from a solid axle allows the axle to be withdrawn easily from the car in the direction of its axis.

A further disadvantage of an axle including a differential gear is that the differential gear is located centrally of the axle requiring a more involved and expensive drive system for the axle to enable the car wheelbase and other affected dimensions to be maintained within the required limit. The drive to a solid axle is applied at one end thereof, thus alleviating the problem.

The present invention seeks to provide an improved differential gear which enables the aforementioned disadvantage to be minimised.

Accordingly the present invention provides a differential gear for a driven axle for a vehicle, wherein the rotational drives to and from the differential are applied about a common axis.

The application of drive to the differential gear about the same axis about which the differential applies drive to the driven axle and the road wheels of the vehicles enables the differential gear to be located anywhere along the axle and even in one of the driven wheels itself. Locating the differential gear in one of the wheels allows the drive to be applied to the differential gear as close to the wheel as possible, as in a solid axle, and enables the road wheels, differential gear and axle to be removed in the same manner as the road wheels and solid axle are removed. i.e. by removing the other road wheel and withdrawing the first roadwheel, differential gear and axle along the axis of the axle.

The present invention is further described hereinafter, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a section through a first embodiment of a differential gear according to the present invention; Fig. 2 is a section through a second embodiment of a differential gear according to the present invention; and Fig. 3 is an exploded section through a third embodiment of a differential gear according to the present invention.

The differential gear 10 illustrated in Fig. 1 comprises a substantially cylindrical housing 12 in which two planetary bevel wheels 14, 1 6 are rotatably mounted at opposite ends of a shaft 1 8 whose axis lies at right angles to and intersects the rotational axis of the housing 12. Two further bevel wheels 20, 22 are secured on independent, driven shaft 24, 26 forming a driven axle and whose rotational axes lie on the rotational axis of the housing 12, the bevel wheels 20, 22 meshing with the bevel wheels 14, 1 6. As will be appreciated the manner of operation of the differential gear is well known and need not be described here.

Drive is applied to the housing 1 2 via a drive gearwheel 28 through which the driven shaft 24 freely passes, the gearwheel 28 being secured to the housing 12 by means of, for example screws 30, or rivets (not shown) or by keying. As illustrated the gearwheel 28 is intended to be driven via a drive shaft parallelled with the driven shaft 24 but may alternatively be a bevel gear driven via a prop shaft at an angle to the driven shaft 24.

Since the differential gear is primarily intended for model racing cars the driven shaft 24 is rigidly connected to a road wheel (not shown in the drawing) at its other end. The driven shaft 26 is also secured (for example splined or keyed) to a cylindrical member 32 which surrounds the housing 12 and which mounts a tyre (not shown) between retaining flanges 34. A clearance is maintained between the housing 12 and cylindrical member 32 to allow for free relative rotation of the two.

The housing 12 is conveniently a two or more part housing to facilitate assembly of the bevel wheels 14, 16 and 20, 22 and shaft 18 within the housing.

In the modified differential gear illustrated in Fig. 2 the end of the cylindrical member 32 adjacent the gearwheel 28 is rotatably supported on the housing 12 by a bearing 36. As illustrated the outer race 38 of the bearing is secured to the member 32 while the housing 12 forms the inner race but this situation could be reversed, or the member 32 and housing 12 may form respectively the outer and inner races or be secured thereto.

In the embodiment shown in Fig. 3 the housing 12 is in two parts 1 2a and 1 2b to facilitate assembly, and the gearwheel 28 is secured to the portion 12a. The cylindrical member 32 is secured to a sleeve 40 by means of screws (not shown) with the sleeve 40 being keyed to the shaft 26. The inner end surface 42 of the member 32 bears on a bearing surface 44 of the portion 12a.

The shaft 24 is conveniently splined or keyed into the bevel wheel 20 or is formed in two parts which are splined or keyed together preferably adjacent the gearwheel 28 to enable easy separation of the differential gear and at least the major portion of the shaft 24.

Friction between relatively rotating parts of the differential gear may be reduced by the use of bearings. For example, between driven shafts 24, 26 and the housing 12 and between the bevel wheels 14, 16 and shaft 18.

While the present invention is intended for use in model racing cars it may of course be used in any situation where a differential gear is required, and in any size or class of vehicle.

The various parts of the gear according to the present invention may be made of any suitabie material, for example plastics material.

Claims

1. A differential gear for a driven axle for a vehicle wherein the rotational drives to and from the differential are applied about a common axis.

2. A differential gear as claimed in claim 1 wherein the differential gear is mounted within a cylindrical member adapted to serve as a wheel hub.

3. A differential gear as claimed in claim 1 or 2 wherein the housing of the differential gear is a two-part housing.

4. A differential gear as claimed in any of claims 1 to 3 wherein the driven axle is detachably splined to the differential for ease of separation.

5. A differential gear substantially as hereinbefore described with reference to Figs. 1, 2 or 3 of the accompanying drawings.

6. A model car having a differential gear as claimed in any of claims 1 to 5.