This invention relates to a drive system for auxiliary equipment, particularly on vehicles.
Typically, auxiliary equipment such as water pumps, compressors, electric generators, air conditioners and so on are required to be mounted in transportation vehicles such as three or four wheel vehicles. The auxiliary equipment, which is provided for applications external to the vehicle, is then operated at a required site such as a building site where, for example, an air compressor may be required or an electric generator may be required to power a lighting system or to provide power for operation of electrical tools. Often a separate engine, to the prime mover engine for the vehicle, must be mounted on the vehicle to supply sufficient power to drive the auxiliary equipment when located at the required site.
Such a system has many disadvantages. Provision of an additional engine requires additional cost. Further, mounting of an additional engine on a vehicle requires additional space, additional vehicle strength and additional weight. Problems of vibration and cleanliness also arise.
A response to these problems has been to use a Power Take Off (PTO) system which is available for some vehicles. In a PTO system, the engine of the vehicle itself is used to drive the auxiliary equipment mounted on the vehicle. An example of a PTO system is a tipper truck where a hydraulic pump is driven by the PTO. A disadvantage that arises in PTO systems is that such systems are directly coupled to the vehicle engine, albeit through some transmission that operates more or less continuously perhaps as disclosed in US Patent No. 4674612. This leads to a drag on the engine when the PTO is not in operation. In such case, the auxiliary equipment runs continuously causing unwanted power wastage, and wear and tear of components within the engine and auxiliary equipment.
It is an object of the present invention to provide an auxiliary equipment drive system which is less subject to the above noted disadvantages, particularly noting the disadvantages of prior PTO drive systems.
With this object in view, the present invention provides an auxiliary equipment drive system comprising:

a prime mover engine; and
an auxiliary equipment item couplable to the prime mover engine through a drive means co-operating with said auxiliary equipment item such that the prime mover engine is capable of driving said auxiliary equipment item when coupled thereto through said drive means
wherein said drive means is selectively operable such that said prime mover engine only drives said auxiliary equipment item when said drive means is in prime mover engine driven state.
The prime mover engine is advantageously the engine used to power a vehicle, that is, to enable operation - in terms of driving - of the vehicle. Therefore, the prime mover engine is typically an internal combustion engine whether operated with liquid fuel, gaseous fuel or with either. In a situation where more than one prime mover engine is required, this also falls within the scope of the present invention.
An "engine driven state" is defined herein as a state in which operation of auxiliary equipment is required and the prime mover engine, as a convenient source of motive power, is required to power the auxiliary equipment. The drive system of the invention does not preclude a situation in which the auxiliary equipment may, alternatively, be driven by an external power source independent of the prime mover engine. For example, situations may be envisaged where engine powering of the auxiliary equipment is desirable, perhaps in remote locations where power sources are not readily available. In other situations, power may be more readily available and the auxiliary equipment may potentially function better when operated through that readily available power source. From the foregoing discussion, it may be understood that operation of the auxiliary equipment item is not typically required during, or incidental to, the normal driving of the vehicle along a road to the site at which the auxiliary equipment item will be used.
Putting the auxiliary equipment into an "engine driven state" may be achieved in a number of ways. Only when operation of the auxiliary equipment item is required, is the drive means connected, or coupled, to the prime mover engine through a transmission including a clutch. A clutch is an advantageous means for achieving such a connection. The clutch may be an electromagnetic clutch which is

engaged to bring the drive means into connection with the prime mover engine when the clutch is powered to cause such connection. To this end, the electromagnetic clutch is advantageously powered with a suitable power source such as a direct current (DC) power supply when operation of the auxiliary equipment item is required; that is, with the auxiliary equipment item being in an engine driven state. A suitable DC source is a battery. An alternating current (AC) supply preferably obtained from the magneto of the vehicle powered by the prime mover engine may also be used as a source of power. In such case, an AC/DC converter is required to be used to convert the AC supply from the magneto to a DC supply. However, an externa! source of DC power may also be employed. Powering of the clutch may be actuated, only when required by an operator, by a switch in a control panel for the vehicle whether in the driver compartment and/or elsewhere in the vehicle. It will therefore be understood that operation of the prime mover engine is an insufficient condition for operation of the auxiliary equipment item.
The drive means may include a suitable power transmission between the auxiliary equipment item and the prime mover engine. For example, both the prime mover engine and auxiliary equipment item may each have a drive or crankshaft. These may be coupled, when operation of the auxiliary equipment item is required, through a drive belt or chain which causes the drive or crankshaft of the auxiliary equipment item to rotate when the clutch is engaged. The transmission system of the prime mover may have as many gears as deemed necessary and including a neutral gear.
The drive or crankshaft of the prime mover engine may be extended to accommodate the clutch, advantageously the electromagnetic clutch as above described. Alternatively, an extension may be coupled to a crankshaft, perhaps after manufacture of the vehicle and enabling a retrofitting operation, to accommodate the clutch.
The auxiliary equipment item may be operated at the same time as the vehicle is operating, the prime mover engine enabling both operation of the auxiliary equipment item and the vehicle itself. During the use of the auxiliary equipment item,

the vehicle will typically be stationary. At the same time, the prime mover engine transmission is preferably in the neutral gear position.
The auxiliary equipment item may be mounted on a loading tray of a vehicle. Advantageously, the auxiliary equipment item is mounted above the prime mover engine crankshaft. The auxiliary equipment item may be mounted above an outer end of the prime mover engine crankshaft. Alternatively, the auxiliary equipment item may be mounted at some distance, in a horizontal plane from the crankshaft of the prime mover engine, conveniently the outer end of the crankshaft, by providing a suitable power transmission arrangement which, though as above described, may include additional linkages or parts in the drive means to ensure effective selective operation of the auxiliary equipment item.
In another embodiment of the invention, there is provided a vehicle comprising the above described auxiliary equipment drive system. The vehicle may be a three or four wheeled vehicle The invention may also be employed to a two wheeler.
In a still further embodiment of the invention, there is provided an auxiliary equipment item, such as a compressor or generator, driven by the above described drive system.
The auxiliary equipment drive system of the present invention may be more fully understood from the following description of a preferred embodiment thereof made with reference to the accompanying drawings in which:
Fig. 1 is a schematic diagram of an auxiliary equipment drive system of one preferred embodiment of the present invention;
Fig, 2 is a detailed view of the prime mover engine of the drive system of Fig. 1 and showing an arrangement for coupling the prime mover engine with an auxiliary equipment item;
Fig, 3a & 3b illustrate the side view and top view respectively of the mounting of an auxiliary equipment item in a vehicle in accordance with one embodiment of the present invention; and

Fig. 4a & 4b illustrate the side view and top view respectively of the mounting of an auxiliary equipment item in a vehicle in accordance with another embodiment of the present invention.
With reference to Figs. 1 to 3b, there is shown an auxiliary equipment drive system 100 for a three wheeler vehicle (not shown). Drive system 100 comprises a prime mover engine 8 being an internal combustion engine; and an auxiliary equipment item, such as a compressor 16 which might be used to deliver compressed air for use at a building site. Compressor 16 is mounted on a loading tray 22 connected to structural frame members 42 of a vehicle 40 .above the prime mover engine 8. Compressor 16 is coupled to the prime mover engine 8 through a drive means 30, which will be described in more detail below, co-operating with the compressor 16 such that the prime mover engine 8 is capable of driving the compressor 16 when coupled thereto through the drive means 30. However, the drive means 30, rather than being driven whenever prime mover engine 8 is in operation in neutral gear position, is selectively operable such that prime mover engine 8 only drives compressor 16 when the drive means 30 is in a prime mover engine driven state. During such operation of the compressor 16, the vehicle will be stationary.
The drive means 30 comprises a number of parts or linkages. First, prime mover engine 8 drives a crankshaft 9. An electromagnetic clutch 10 is mounted on the crankshaft 9 of the prime mover engine 8. The electromagnetic clutch 10 is mounted at an outer end of crankshaft 9 on an output shaft 11 such that clutch 10 freely rotates on output shaft 11. Crankshaft 9 may be provided with an extension to accommodate the electromagnetic clutch 10.
A clutch plate 18 is rigidly mounted on the base plate or bolt 7 of the crankshaft 9 to rotate along with crankshaft 9. A sprocket 12 is rigidly mounted to the output shaft 11. Sprocket 12 drives another sprocket 13 which is rigidly mounted on a driveshaft 14 of compressor 16. When electromagnetic clutch 10 is engaged, rotation of output shaft 11 and sprocket 12 will cause rotation of a chain drive 15 driving the sprocket 13 and, consequently, the compressor 16. In such an arrangement, there is benefit in having the compressor 16 mounted vertically above

an outer end 9a of prime mover engine crankshaft 9 so that chain drive 15 and sprockets 12 and 13 are in an operable alignment allowing operation of the drive means 30 made up of these parts or linkages.
However, the drive means 30 - in the form of the sprocket/chain arrangement - will only operate when operation of the compressor 16 is required by an operator who operates a switch in a driver compartment 46 of vehicle 40 to do this. In this v^ay, wear on the compressor 16 - which would be expected using a power take off (PTO) arrangement which would run the compressor 16 whenever the prime mover engine 8 is operating - may be avoided. Put another way, operation of prime mover engine 8 alone is an insufficient condition for operation of the compressor 16 (or other auxiliary equipment item). The switch requiring operation of compressor 16 must also be activated, that is, switched "ON". The manner in which such selective operation of compressor 16 may be achieved will now be described.
Electromagnetic clutch 10 may only be engaged, to enable operation of compressor 16, in the above described manner, when supplied with DC power converted from an AC power supply from a magneto (not shown) of prime mover engine 8. In this situation, the auxiliary equipment item, that is compressor 16, is in an prime mover engine driven state in which operation of compressor 16 is required and the prime mover engine 8 is required to power or drive compressor 16.
During the situation when DC power is not supplied to electromagnetic clutch 10, a small clearance (0.3 to 0.5 mm) is maintained between clutch plate 18 and electromagnetic clutch 10. In this non-engine driven state, power is not transmitted
to compressor 16 through electromagnetic clutch 10. During this time, prime mover engine 8 may be operating, perhaps to enable vehicle 40 to be driven to a required site, but compressor 16 is not driven. This avoids drag on the prime mover when the compressor is not coupled.
Where operation of compressor 16 is required, the transmission of the prime mover engine 8 is maintained in a neutral gear position and DC power is supplied from the engine magneto to electromagnetic clutch 10. The clutch 10 is thus

magnetised and engages with clutch plate 18 such that motive power from the prime mover engine 8 is supplied to the driveshaft 14 of compressor 16 through the sprocket/chain arrangement described above. Compressor 16 is then operated as required.
Another embodiment of the auxiliary equipment drive system wilt now be described with reference to Fig. 4a & 4b. Here, an auxiliary equipment item 16 again a compressor is mounted on loading tray 22 above prime mover engine 8 though at a distance in a horizontal plane from prime mover engine 8. In this case, an additional linkage is empioyed as will now be described. In this case, sprocket 12 is engaged, through chain drive 25, with another sprocket 20, which is intermediate the prime mover engine 8 and compressor 16. Intermediate sprocket 20 is mounted on a frame member (not shown) of vehicle 40. Intermediate sprocket 20 is engaged through a further chain drive 21 with sprocket 13, which as above described is rigidly mounted on the driveshaft (not shown but analogous to driveshaft 14 described above) of compressor 16.
Again, when operation of compressor 16 is required, the electromagnetic clutch 10 is energised by the DC power supply, it becomes magnetised and engages with clutch plate 18. Power is then transmitted to rotate sprockets 12, 20 and 13 engaged with chain drives 21 and 25 to drive compressor 16 driveshaft and enable operation of compressor 16 for so long as is required by the operator.
Modifications and variations to the auxiliary equipment drive system of the present invention may be understood by the skilled reader of this disclosure. Such modifications and variations are deemed within the scope of the present invention.

CLAIM:
1. An auxiliary equipment drive system comprising:
a prime mover engine; and
an auxiliary equipment item couplable to the prime mover engine (8) through a drive means co-operating with said auxiliary equipment item such that the prime mover engine is capable of driving said auxiliary equipment item when coupled thereto through said drive means wherein said drive means is selectively operable such that said prime mover engine only drives said auxiliary equipment item when said drive means is in prime mover engine driven state.
2. A drive system as claimed in claim 1 wherein, when an external power source is available, said auxiliary equipment item is operated through that power source independently of operation of said prime mover engine.
3. A drive system as claimed in claim 1 or 2 wherein, only when operation of the auxiliary equipment item is required, is the drive means connected, or coupled, to the prime mover engine.
4. A drive system of claim 3 wherein said drive means is connected, or coupled, to the prime mover engine by a transmission including a clutch.
5. A drive system of claim 4 wherein said clutch is an electromagnetic clutch powered by a direct current (DC) power supply.
6. A drive system of claim 5 wherein said electromagnetic clutch is powered by direct current (DC) obtained by converting an alternating current (AC) supply from a magneto of said vehicle powered by the prime mover engine .
7. A drive system of claim 4 wherein an external source of power is employed to power an electromagnetic clutch.

8. A drive system of any one of claims 5 to 7 wherein said electromagnetic clutch is mounted on a crankshaft of said prime mover engine.
9. A drive system as claimed in any one of the preceding claims wherein said drive means includes a power transmission between the auxiliary equipment item and the prime mover engine.
10. A drive system of claim 9 wherein both the prime mover engine and auxiliary equipment item each have a drive or crankshaft coupled, when operation of the auxiliary equipment item is required, through a drive belt or chain which causes the drive or crankshaft of the auxiliary equipment item to rotate when a clutch is engaged.
11. A drive system of claim 9 wherein, during operation of said auxiliary equipment item, said transmission of said prime mover engine is in neutral gear.
12. A drive system of claim 8, 10 or 11 wherein the drive or crankshaft of the prime mover engine is extended to accommodate said clutch.
13. A drive system of any one of claims 10 to 12 wherein an extension is coupled to said drive or crankshaft to accommodate the clutch.
14. A drive system of any one of claims 1 to 13 comprising a switch operable to operate said drive means only when operation of said auxiliary equipment item is required, operation of said prime mover engine being an insufficient condition for operation of said auxiliary equipment item.
15. A drive system of any one of the preceding claims wherein said auxiliary equipment item is mounted on a loading tray of a vehicle.
16. A drive system of any one of the preceding claims wherein said auxiliary equipment item is mounted above said prime mover engine crankshaft.

17. A drive system of claim 16 wherein said auxiliary equipment item is mounted above an outer end of said prime mover engine crankshaft.
18. A drive system of any one of the preceding claims wherein said auxiliary equipment item is mounted at a distance, in a horizontal plane from said prime mover engine crankshaft.
19. A drive system of claim 18 wherein said auxiliary equipment item is mounted
at a distance, in a horizontal plane from an outer end of said prime mover
engine crankshaft.
20. An auxiliary equipment item driven by the drive system of any one of the preceding claims.
21. A vehicle comprising the drive system of any one of the preceding claims.
22. A vehicle as claimed in claim 21 being a three wheeler vehicle,