148
W. A. REYNOLDS
coal burners. By cannibalising trucks it was possible to have 3 engines for every 2 trucks so that each engine would be stripped down and rebuilt every 2,000 km. This may appear excessive but the engines, due to the low power on gas, required bottom gear for gradients that on petrol would need third gear. The revolutions per kilometre were therefore high. Despite filtering of the charcoal gas, dust carried through to the engine and gave heavy cylinder and bearing wear.
The lack of replacement parts and lubricating oil was a major problem since neither could be purchased in China except at very high prices and of doubtful origin. Brake and clutch linings, hydraulic brake components and fluid, and electrical components could not be satisfactorily substituted. The problem, especially that of lubricating oil, was not solved until late 1944 when an allocation of 1 ton air freight per month from Calcutta to Kunming was obtained especially for the import of spare parts.
Charcoal Gas Power for Road Transport
The gas engine was a common source of power for factory installation between 1880 and 1920 in Europe and America. The usual form was a single horizontal cylinder with sliding crosshead and connecting rod turning a large flywheel. Flame or spark ignition was used and the fuel was coal gas or producer gas. Because of the fuel characteristics a long stroke and a high compression ratio (of the order of 15:1) are required for maximum efficiency.
During World War I town gas was used as a fuel for motor vehicles in the UK, and from 1931 onwards research in the subject was carried out at Birmingham in both the Mechanical Engineering Department of the University and the Industrial Research Laboratory of the City of Birmingham Gas Department. This is described by Clarke (Ref. 2). The use of town gas depends on containers, either high pressure cylinders or 'gas bags' which are refilled from the main supply.
An alternative system is to use producer gas, generated from a carbon-base fuel in an apparatus attached to the vehicle. This method received much attention in the 1930's and different systems are described by Goldman and Clarke Jones (Ref. 3). Producer gas is made by burning carbon in the form of peat, wood, anthracite,