A NEW PETROL-ELECTRIC CHASSIS.
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Designed for 2i-ton Gross Loads and 21on Net Loads, the New Stevens-Thornvcroft is Suitable for a Bus, or a 20-seater Motor Coach.
ANEW PETROL-ELECTRIC chassis for gloss loads of 50 cwt. and net loads of 2 tone, bas just been completed for Stevens Petrol Electric Vehicles, Ltd., 68, Victoria Street, Landoll, S.W.1, by J. I. Thornycroft and Co., Ltd., Basingstoke.
The chassis is a combination of the well known B.T. type Thornyeroft chassis (which in 1921 accomplished such a meritorious performance in a 1,260-mile road trial under the supervision of the Royal Automobile Club, for which performance the Dewar Trophy was awarded to the manufacturers) and the Stevens electric transmission, which displaces the gearbox and clutch.
The vehicle will be known as the B.T. Stevens petrol-electric, and it is considered to be most useful for single-deck omnibuses and 18-20-seater motor coaches. There are many subsidiary purpdses to which a chassis of this type may be put, for it can be provided with a body and equipment so that the electric current from the dynamo, which is the first unit of the Stevens system, can be employed for arc welding, electric lighting, electric heating, power transmission, and battery charging.
The vehicle has a 14-ft. wheelbase, the engine being the Thorn.ycroft standard A.B. 4, its four cylinders being cast inonobloc and having a bore of 4,ins., the piston stroke being 51 ins. The maximum horse-power developed by this engine is about 30. It has overhead inlet valves located in a detachable cylinder top cover, the exhaust valves being in the cylinder block, both valves being operated by one camshaft. The transmission consists of (1) a special electric generator driven direct by the petrol engine, and being of the four-pole mterpolar type, compound wound and provided with commutating poles; (2) an electric motor directly coupled to the cardan shaft; and (3) a reversing and speed regulating controller, robust in construction, bolted to the chassis frame and protected against the weather. The
insulation of the windings is of the best quality, and the whole of the gear throughout is of substantial construction.
From the electric/motor the power is transmitted by a propeller shaft, universally jointed at both ends to an overhead worm-geared back axle. The frame is deep in section, the springs are of ample length, and the vehicle is mounted on cast-steel wheels, 35 hie, diameter over the tyres, the latter being 900 mm. by 85 mm. on the front wheels and 900 .mm. by 90 mm. twins on the rear, the fitting size being 741 mm. The track of the front wheels is 5 ft. 2; ins, and the distance between the centres on the tyres of the rear wheels is 4 ft. 8 ins.
The electrical transmission acts automatically as a gprag and serves effectively to prevent the vehicle from running back, except at very low speed, if unexpectedly brought to a standstill on a steep gradi e nt without the brakes being applied. The first of this:new type chassis has n ow been completed, and is expected in a few days to be on the road.