Wilson-Pilcher

The engine was suspended in the conventional location at the front of the car at a slight angle to allow straight drive to the rear axle, and with the cylinders lying between the frames of the chassis. The mountings above the engine allowed it to rock sideways to some extent, this being limited by a pair of helical springs at the front and by diagonal radius rods connecting the rear of the gearbox to the ends of the rear axle. In this way the mechanical vibration of the engine and transmission was largely isolated from the chassis and occupants. Images below are for the 1904 six-cylinder version of the car.

• Wilson-Pilcher Layout with Bodywork Removed
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  Chassis Layout viewed from above
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  Chassis Layout viewed from side

Both the four cylinder and six cylinder engines had identical cylinders of 3.75 inches bore and stroke. Each cylinder was bolted onto the aluminium crankcase, with the cylinders offset to allow each to have its own crank pin. Intermediate crankshaft bearings were provided between each pair of cylinders. The inlet valves were automatic on the top of the cylinders, and the exhaust valves were beneath the cylinders, operated by a camshaft beneath the crankshaft. The engine ratings of 12-16 hp for the four cylinder, and 18-24 for the six cylinder are described as "the lower powers mentioned in both cases are those which can be obtained on the road-wheels under average running conditions - hill-climbing - whilst the higher powers mentioned are those developed by the respective engines on the brake, when running at a speed of 1,000 revs. per min."

The single gear-driven camshaft is arranged so that each lobe operates the exhaust valves on a pair of cylinders. Roller cam followers are used. In the middle of the camshaft is a speed governor. The governor causes lengthwise movement of the camshaft, and the cam-lobes are slightly widened to allow for this. The speed-regulation caused by the governor is set by a lever on the steering column and the same mechanism advances the spark with increased engine speed. The operation of the governor is overridden by the foot throttle (either slower or faster - the pedal is of a type allowing it to be raised or depressed), but for normal running the governor offers an early form of cruise control.

• Wilson-Pilcher Engines
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  1904 Wilson-Pilcher Flat-6
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  1904 Flat-6 in situ
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  1904 Flat-4 engine with lower crankcase cover removed

The gearbox was housed in an aluminium casing and bolted directly onto the engine. It contained a main cone clutch and two epicyclic gears, allowing four forward speeds. All gears are helical which substantially reduces gear noise, and the drive is direct through in top gear. The main foot-operated clutch could be latched in the disengaged position by depressing and moving the foot pedal to one side, allowing the engine to be started and idled without driving the wheels. Once the clutch pedal was released gear changes were made using a hand lever without the need to use the main clutch. This image also shows the gearbox attached to the four-cylinder engine and clearly shows the offset between the cylinders, and the flywheel at the front of the engine which doubled as a fan. The epicyclic gear next to the clutch has a reduction ratio of 2.7:1, the other has a reduction ratio of 1.7:1. The latter is used to give 3rd gear, the former to give 2nd gear, and both together give 1st gear, all operated by a single hand lever. The fact that reverse is not provided by the gearbox, but instead by the rear axle (see below), and operated by a reversing lever separate from the gearchange lever, means the cars had as many reverse gears as they did forward gears. The use of helical planetary gears later became the main gear mechanism for automatic transmissions, the key difference from the Wilson-Pilcher design being that gear changes were made automatically and not by moving a gear change lever.

• Wilson-Pilcher Gearbox
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  Four cylinder engine and gearbox with top covers removed
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  Sectional view of the clutch and epicyclic gearbox

The rear axle, like the gearbox and engine, was housed in an aluminium case. In addition to the normal function of providing a differential, it also provided the reverse gear, and contained the rear brake (foot operated). Reversing is achieved by changing which of the large bevel gears (these days known as crown wheels) engages with the drive on the end of the propshaft. Like the gearbox, all gears within the axle are helical cut.

• Wilson-Pilcher Rear Axle
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  Rear axle with top cover removed