After a series of cars blew up, Thompson & Thomson and Tintin came to the conclusion that the petrol was doctored. Thompson and Thomson also came up with the theory that the petrol is being doctored by car repair companies as they are the one who benefited maximum from a blown up engine. So they decided to investigate the biggest car repair and breakdown company “Autocart” (in English version) because they advertise the most. The two detectives got a golden opportunity when they found out that “Autocart” had advertised for drivers for their breakdown trucks. Thompson and Thomson joined the company and were handed over a Chevrolet 1936 based recovery truck to drive.
Chevrolet introduced the inline six cylinder engines on their light trucks in 1929. By 1936, these were 3,392 cc (207 cu-inch) naturally aspirated petrol engines which breathed through overhead valves. These engines produced 72 BHP at 3,200 rpm and 210 N-m (155 lb-ft) of torque at 900 to 1,500 rpm. Engine cooling and cam shafts were improved for 1936 leading to an improvement in performance.These engines were popularly called “Stove Bolt” engines as the engine’s quarter inch slot-head bolts resembled the slot-head bolts used to hold together wood burning stoves from the 1930s.
These trucks were available in a number of versions and chassis sizes varying from 2,844 mm (112″) up to 3,988 mm (157″). The load carrying capacities varied between half and one and a half tons. These trucks were suspended by semi-elliptic springs at the front and rear. The engines drove the rear wheel. Front axle was reversed Elliot I-beam sections while the rear was semi-floating type.
Engine torque was transmitted to the rear wheels through a three speed gear box with selective synchro-mesh and a single dry plate clutch. Stopping power to these trucks was provided by a set of four internally expanding drum brakes which were operated hydraulically.
As was the norm in the 30s, the trucks had a 6 volt electrical system. However, for use as bus, they needed to be converted to 12 volt system. They were fitted with headlamps with non glare lenses. Tail and stop lights were provided as standard. Dipper for headlamps was foot operated. Instrumentation included speedometer, fuel gauge, oil pressure gauge, water temperature indicator and ammeter. By this time electrically driven automatic windshield wipers were also provided by Chevrolet as standard. Wheels were wire wheels with internal drop center rim for the light trucks and pressed steel for the heavier trucks.
Chevrolet offered the trucks in three standard colours, Swift red with silver stripes, Export blue with silver stripes and Brewster green with Gigoglo green stripes. In addition, 13 optional body colours and nine stripe colours were offered which could be combined in various options to customise the trucks to the owners taste. A number of options were offered for the interiors also.