New Underfloor engined Coach Chassis for the Home Market
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FOLLOW1NG the introduction last autumn of the Atkinson export passenger chassis, a new model has -been developed for the home market. This has been designed to meet. the demand for an underfloor-engined coach maximum-load chassis.
• The frame consists of 8-in, by 3-in. channel-section side-members which are slightly cranked laterally, to accommodate the power unit but are formed without wheel-arches. For cross-bracing, 4-in.-diameter tubular members are 'employed. The overall length of the chassis is 29 ft. 6 ins., providing for a 30-ft. by 8-ft. body, and the wheelbase measures 16 ft. 6 ins. The frame is 3 ft. 8 ins, wide as its narrowest point, and 4 ft. I in. wide from the engine to the rear end.
Engine Mounted Centrally The power unit employed is the Gardner 6HLW, a Six-cylindered direct-injection oil engine of 41-in, bore and 6-in, stroke, developing 112 b,h,p. at .the governed speed of 1;700 r.p.m.; a torque of 358 lb.-ft. is given at 1,300 r.p.m. Mounted as a unit with clutch and gearbox, the engine is disposed cen.trally in the chassis with rubber insulation at each location point.
Ample cooling is provided by a largediameter fan mounted integrally with the radiator, in conjunction with a centrifugal water pump, the system working under thermostatic control. The radiator unit is of the detachable Withnell tube type mounted 'ahead of the front axle and the fan is driven from the power unit by a Layrubjointed shaft.
The single dryplate clutch is of 16-in. diameter, and has a stop and two-stage adjustment to provide for wear on the facings. Clutch-slip torque is stated to be 510 lb.-ft., a figure which should be more than equal to all driving demands. Controlled by the Atkinson single change-speed lever, the gearbox has five forward speeds, including indirect top, and a reverse. The ratios provided are .762 (indirect top), 1, 1.63, 2.79 and 4.97 to 1, and 5.56 to 1 for reverse, A single tubular propeller shaft carries the drive to the rear axle, which is of the heavy-duty hypoid type, and, in order to meet demands for differing conditions, alternative ratios of 5.25 to 1 or 4.78 to 1 can be supplied. Straightthrough controls are employed in all instances.
Particularly long semi-elliptic springs are employed front and rear, high deflection characteristics being calculated to give the utmost comfort for coaching journeys. Munroe shock absorbers are fitted at the front. A steeringcolumn of more substantial appearance than that on the export version has been incorporated with steering gear of the Marles cam and double-roller type.
Clayton Dewandre triple-servo braking is standard; with separate vacuum cylinders mounted on each front-axle swivel, with a main vacuum-servo controlling the rear wheels through a crosshaft. The hand brake, which is placed to the right of the driver, pulls On and is effective on the rear wheels only. Dimensions of the brake drums are 161 ins. by 4 ins, at the front. and 151 ins. by 7 ins, at the rear.
Singlefront and twin rear pressedsteel disc wheels are held by 10 1-in.diameter studs. Standard lyre size is 10,00 by 20 ins., although 9.00 by 20 ins. can be used as an alternative, The track 'is 6 ft. l ins. at the fear and 6 ft. 91 ins, at the front. Width over tyres is 7 ft. 114 ins., or fractionally more over the hub-plates.
Fuel Tank Location i • Instruments arc grouped ,n a' panel in front of the driver, the control board being to his right. As with the export model, a 38-gallon fuel tank is used with feed by a camshaft-driven Amal pump, but in this case it is located on the near side of the chassis, just forward of the rear wheels.
When ballasted to thc" fully laden weight, the frame height is 2 ft. Ili ins., or, unladen, 3 ft. 5 ins. ' Minimum ground clearance when fully *loaded is 1101 ins. Overhang is 5 ft. 2 ins. 'at the front, and 7 ft. 10 ins, at the rear. The chassis has a turning circle of 60 ft.
The new design is being listed as Model P.M.746H and the manufacturer is Atkinson Lorries (1933), Ltd., Winery Lane, Walton-le-Dale, Preston, Lancs.
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