Air Starters for Atkinson 25-ton Tippers
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SPECIAL eight-wheeled heavy-duty Chassis are being supplied by Atkinson Vehicles, Ltd.. Preston, Lanes, to Roadstone, Ltd., Dublin, Ireland. The. 15-ft. 11-in.-wheelbase chassis have been designed to handle payloads of up to 25 tons, and meet the specific .requirements of Mr. T. Roche, managing director. Cummins NH-6-B12.2-litre six-cylindered oil engines have been specified. They have .a gross output of 210 b.h.p. at 2,100 r.p.m., with a peak torque output of 580 lb,-ft. at 1.500 r.p.m.
An unusual feature of the engine installation is the use of an Ingersoll-Rand air starter motor, air starting being employed extensively in the Roadstone fleet. Power is drawn from a large reservoir mounted transversely across the chassis frame immediately ahead of the rear bogie and having capacity for several starts. This reservoir can be charged from an external source when necessary. The engine exhaust system incorporates a vertical silencer and tail pipe mounted behind the cab.
The ZF AK6-75 six-speed constant-mesh gearbox has a topgear ratio of 0.72 to -1, bottom gear being 6.44 to 1. In conjunction with the 8.25-to-1 final drives of the Kirkstall 81-in-centre overhead-worm rear axles, this overdrive ratio
gives a maximum road speed of 47.25 m.p.h. A BendixWestinghouse dual-circuit air-pressure braking system is fitted, all eight wheels being braked.
The suspension consists of semi-elliptic springs at each axle, the two front axles having telescopic dampers, and 11.00-24-in. tyres are fitted. The chassis frame has Fin.-thiek side members with a parallel depth of 11 in. throughout and 3-in. flanges. They are boxed and flitched at highly stressed points. There are five cross-members, gusseted and bolted.
The chassis are equipped with Marks cam-and-double-roller steering with Adamant hydraulic servels. They are being sent to Ireland with standard Atkinson plastics-panelled cabs equipped with twin air horns on the roofs and air-operated windscreen wipers. Equipment includes a front lowing member. a rear spring-mounted drawbar. cab heater and demister. and -trailer-brake couplings.