Bonhams engine high res.

Twin 40mm horizontal Solex bolted directly on the manifolds in the Grand Prix but twin zenith triple diffuser carburetters and barrel throttle Claudel-Hobson were also tried. Fuel feed by pressure from 60-gallon tank positioned by leather lined nickel plated steel straps at rear.

Twin Scintilla magnetos mounted on the front of the timing gear case operated via Vernier couplings at crank speed. Two plugs per cylinder, one centrally placed in the cylinder head, 10 degrees inclined to the vertical and the other placed nearside on the inlet side of cylinder head.

Four forward and one reverse speed gearbox in unit with engine mounted directly on the chassis. Inverted cone fabric clutch carried on light ribbed steel flywheel. Hotchkiss-type drive; transverse driven by a worm gear reduction for servo motor braking system (removed after the GP). Open hollow propeller shaft with two Hooke – type universal joints at each end sloping upwards from gearbox to the rear axle. Straight cut crown wheel and pinion drive through a normal differential to the hollow half shafts. The crown wheel housing is offset towards the nearside. Gear ratio overall Top (14 tooth pinion, 55 tooth crown) 3.928:1; 3rd 4.6099:1; 2nd 6.383:1; 1st
10.942:1. Other ratio recorded 4.08:1.

Dry sump lubrication. Pressure/scavenge cluster gear type oil pump driven directly from the gear train at front of the engine at near crank speed. High pressure lubrication is limited to the big – ends. Oil pressure is regulated through hand controlled visual feeds. Drain pipes in the valve covers returning surplus oil to the sump. Separate five gallon fabricated sheet brass oil tank slung under driver and riding mechanic seats.

Centrifugal water pump mounted on the front of the timing gear case and driven directly. Two branch pipe leads from the cylinder head to the radiator and four branch pipe from the pump to the cylinder jackets, entering on the
exhaust valve side. Radiator is provided with by-pass pipe leading from top to bottom tank to counteract water pile-up in the top tank when pump is at full speed. Serck manufactured pressure relief valve radiator cap.

Braking System
Brakes to all four wheels actuated by hand lever (rear) and foot pedal. Brake cables operated by Hispano Suiza type servo mechanism driven from the gearbox main shaft (removed after the Grand Prix), running over pulleys, adjustable by ratchets below the riding mechanic. The Perrot- type front brakes are ribbed light section steel and are larger diameter than rear; cast iron shoes.

1922 works cockpit copyInstruments
Jaeger revolution counter driven from the forward end of the camshaft, Sunbeam oil pressure gauge, fuel tank air pressure gauge, twin magneto switches, twin glass oil restrictors. Under-reading of 300rpm on the Jagaer revolution counter was a contributing factor in over-stressing the engines during the race.