They are sold for fitting to heavy vehicles such as trucks or fire engines. Known apparatus of this kind is . bulky and unsuitable for fitting to light lorries, cars and utility vehicles such as vans or "Land Rovers" (Land Rover is a Registered Trade Mark) .

It is an object of the present invention to provide such apparatus which is suitable for all such applications, as well as for static applications such as for fixed installations. According to the present invention there is provided power take-off apparatus which comprises a rotary power input means, primary rotary power output means substantially coaxial with said power input means for delivering power to a drive line of a vehicle (as herein defined) , and auxiliary rotary power output means sub¬ stantially coaxial with said power input means, selector means being provided to select whether or not power is delivered to said auxiliary rotary power output means.

In the foregoing definition and elsewhere where the context permits the term "vehicle" includes not just land-vehicles but other vehicles such as watercraft and aircraft.

Preferably the power input means is arranged to couple directly to the drive shaft of a motor, engine or gearbox.

The selector means may be directly manually operated, e.g. by means of a selector lever, or may be operated e.g. electrically, for example by means of a solenoid, hydraulically or pneumatically.

It is an important part of the present invention that the auxiliary rotary power output be axially aligned with the rotary power input since considerable advantages of.compactness and weight saving, can thus be achieved. It is possible however for the take 'off apparatus of this invention to include one or more further auxiliary rotary power outputswhich may be ^* abaxial with respect to the rotary power input.

In a preferred embodiment the apparatus comprises a shaft arranged to connect at its respective ends with a power input such as the drive shaft of a gearbox or the propellor shaft of a vehicle and with a primary power output such as the continuation of the propeller shaft of a vehicle. The shaft is preferably arranged to couple together said power input and said primary power output by means of a sliding engagement member preferably located about the shaft and preferably sliding on one or more splines formed in said shaft. The engagement member is also used to engage the power input means with said auxiliary power output means e.g. in the form of a pulley mounted for rotation about the axis of rotation of the input means, by sliding to

make such engagement.

Preferably the sliding engagement member is in the form of a dog arranged to mesh with dogs provided respectively on said primary and auxiliary power output means. It is of course possible for the shaft to be coupled permanently to said primary power output means and for the sliding engagement member to mesh with dogs provided for the purpose on the power input means.

The arrangement may be such that selection of the auxiliary power output prevents power transmission to the primary power output and vice versa i.e. that the power take off can be utilized only when the vehicle is not being driven, or the arrangement may be such that power may be supplied simultaneously to both primary and auxiliary power output by appropriate selection.

It is to be understood that any suitable apparatus may be driven from the auxiliary power output means such as an alternator or generator, an air compressor or a hydraulic pump or motor. An embodiment of a power take off apparatus according to the present invention will now be described by way of example only, by reference to the accompanying drawings in which:

Fig. 1 is a cross-sectional plan of a power take/off apparatus according to the present invention;

Fig. 2 is an end elevation of the apparatus of Fig. 1; and

Fig. 3 is a detail cross-sectional side elevation showing a selector mechanism.

Referring to the drawings a power take-off apparatus 1 comprises a casing 2. A shaft 3 is arranged for rotation in the casing and at one end 4 extends out of the casing. Said one end 4 is splined and receives a connecting flange 5 secured thereto by means of, nut 6. The connecting flange 5 is for connecting the through shaft 3 to e.g. the drive shaft of a gearbox or the propellor shaft of a vehicle (not shown) .

Mounted for rotation in bearings 7 within one end of the casing 2 is a dog flange 8, concentrically arranged with respect to shaft 3 and provided with bearings 9 to support shaft 3 in rotation. Dog flange 8 extends out of the casing 2 and is provided with a threadedly recessed attachment flange 10 whereby a pulley or other power output device (not shown) may be secured thereto.

At the other end of the casing 2 there are provided bearings H supporting in rotation a dog flange 12, concentrically arranged with respect to shaft 3 and provided with bearings 13 to support shaft 3 in rotation. Dog flange 12 extends through the said other end of the casing 2 and a flange plate 14 is secured thereto. Flange plate 14 is provided with attachment means in the form of threaded recesses 15 whereby dog flange 12 may be connected to the transmission line (e.g. the continuation of a propeller shaft) of a vehicle (not shown) .

Longitudinally extending splines 16 are provided upon a central portion of shaft 3 and slidably carry a dog 17 thereupon. The dog 17 is ^" arranged to slide between a first position in which it meshes with dog flange 12 to - 5. a second position in which it meshes with dog flange 8. A selector fork 18 engages dog 17 for this purpose and is secured to a selector spindle 18 capable of axial sliding movement between positions limited by spring loaded ball 19 and detent grooves 20, 21.

10 The casing 2 contains oil and includes filler- level, breather and drain plugs to allow for this; suit¬ able oil seals 22 are provided throughout to prevent oil leakage. Mounting points 23 are provided upon casing 2 fo securing it in position in a vehicle or the like. •^5 In use the apparatus 1 is connected e.g. in a propeller shaft of a vehicle (not shown) . With the dog 17 in its rightmost position in Fig. 1 it interconnects shaft 3 with dog flange 12 and transmits drive via flange plate 14 to the continuation of the propeller

20 shaft of the vehicle. In the leftmost position drive to the dog flange 12 is removed and instead transmitted via dog flange 8 and flange 10 to a power output device such as a pulley (not shown) .

Although in the embodiment shown no abaxial

?5 power output is provided, it is envisaged that dog flange 8 could be provided with an external circumferentLal gear ring.e.g. in region 25 thereof, to drive a further output shaft via a gear drive train or other suitable means.

It is to be understood that although the .invention has been described with reference to a unit adapted to be incorporated in a pre-existing transmission line the invention is equally applicable to gear boxes themselves. In other words the present invention embraces a primary gearbox for a vehicle which gearbox includes apparatus as 'defined. The invention also includes a vehicle incorporating apparatus as hereinbefore defined.