With vehicles having transversely mounted engines the conventional lay out physically restricts the arrangement. Conventionally the engine compartment has to accommodate the engine, a clutch and a gearbox within the width of the engine compartment. This imposes constraints on the engine size. Proposals have been made for changing the power transmission arrangement to afford greater flexibility but such arrangements have been complicated.

An object of the invention is to provide an improved power transmission arrangement for vehicles.

According to the invention a power transmission arrangement for a vehicle having an engine to be mounted transversely with respect to the longitudinal direction of the vehicle comprises a gearbox by which drive is transmitted from the engine, and an output shaft from the gearbox coupled to vehicle wheel drive shafts, whereby drive from the engine is transmitted to the driven wheels, the engine output shaft carrying clutch means from which drive-is transmitted to the gearbox, and the gearbox transmitting drive to a longitudinally extending shaft coupled to the wheel drive shafts, the longitudinal axis of the gearbox being arranged to lie at an angle to said longitudinal direction of the vehicle.

By this arrangement the gearbox can lie within the width of the transversely extending envelope defined by the engine and its associated clutch, thereby reducing limitations of engine size with conventional arrangements.

Drive from the clutch to the gearbox may be by a bevel gear pair, and drive from the gearbox

output shaft to said longitudinally extending shaft may be by skew gear means whereby the gearbox extends at an angle to said longitudinal direction and transfer drive transversely from the clutch towards the vehicle longitudinal axis, generally centrally of the vehicle.

The longitudinal shaft may transmit drive to the front wheels, the rear wheels, or both, of the vehicle in a two wheel or four wheel drive arrangement.

In driving the front wheels the longitudinal shaft may transmit drive to a differential and then to drive shafts for each of the front wheels. When driving the rear wheels the longitudinal shaft extends rearwards to a rear differential to which drive shafts are connected to drive each of the rear wheels. In a four wheel drive arrangement the longitudinal. shaft drives the front and rear wheels simultaneously and there may be a differential to apportion torque between the front and rear wheels.

Drive to the front wheels may be through a universal joint or joints in the driving connection between the differential and each of the front wheels.

Further features of the invention will appear from the following description of an embodiment of the invention given by way of example only and with reference to the drawing which is a schematic plan view of a vehicle transmission.

Referring to the drawing a vehicle, which may be a passenger car, a rally or racing car, or other four wheel vehicle, has two pairs of wheels (only one of which is shown) which, in the illustrated arrangement, are each driven.

The vehicle has a transversely mounted engine 10 which extends with its main axis located transversely to the longitudinal direction 11 of the vehicle. The engine 10 is mounted in the usual manner within the front engine compartment (not shown) of the vehicle. The engine 10 is usually an internal combustion engine and has an output shaft 12 transmitting drive to a clutch 13 located at one end of the engine. Output from the clutch 13 is to a pair of bevel gears 14 of which one gear 15 is driven from the clutch 13 and the other gear 16 is the input

gear for a gearbox 17. The bevel gears 15 and 16 are arranged so that the gear 16 has a axis of rotation inclined at an angle a to the longitudinal direction of the vehicle.

The gear box 17 may be of conventional form having a series of gear wheels 19 selectively meshing with a series of gear wheels 20 mounted on a shaft 22, the shaft 22 also lying at the angle a to the longitudinal direction.

The shaft 22 also carries an output gear wheel 23 which is a skew gear meshing with a gear wheel 24 carried on a longitudinally extending shaft 25 extending along the longitudinal axis 11. The skew gear arrangement of gears 23 and 24 permits the shaft 25 to lie at an angle to the gearbox shafts 18 and 22 and the inclined arrangement of the gearbox 17 transfers drive from the clutch 13 towards the central shaft 25.

In the illustrated arrangement the. shaft 25 transfers drive forwardly to the front driving wheels 30 and to the rear driving wheels (not shown) so that the front and rear wheels are driven by the engine.

In the case of the front driving wheels 30 drive is transmitted from the forward end of the shaft 25 through bevel gears 31 to a differential 32 from which drive is transmitted to drive shaft arrangements 33 to each of the wheels 30. As illustrated the drive arrangements from the differential 32 to each of the wheels 30 includes clutch means 34 driving a shaft 37 through a universal joint 35 and the shaft 37 drives a further shaft 38 through a universal joint 36. The provision of the universal joints 35 and 36 permits the drive to the wheels 30 to be directed to the required position taking account of other structural parts of the vehicle (not shown). The clutches 34 are part of the arrangement by which torque to the driving wheels 30 may be controlled especially in the case of racing vehicles.

The shaft 25 also extends rearwardly of the vehicle to drive the rear wheels. Drive to the rear wheels is through a centre differential 40 which is arranged to control the torque transmitted to the rear wheels. Thus the torque available from the engine may be proportioned between the front and rear wheels according to driving conditions and requirements. Drive from the

centre differential 40 is then transmitted to the rear wheels through a differential and to shafts to each of the rear wheels in conventional manner.

It will be appreciated that the clutch 13, gearbox 17 and associated differentials 32 and 40 together with the universal joints 35 and 35 may be located within a common housing to make for a compact and rigid structure.

The positioning of the gearbox 17 behind the engine greatly improves the ability to efficiently use the dimensions of the vehicle to accommodate the engine, to provide for improved weight distribution, and to improve packaging and access to the components whilst permitting the vehicle to comply with vehicle impact requirements..