Commers Converted to Six-wheelers
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cONVERSTONS of various Cornmer
chassis form over 65 per cent, of the production of Douglas Equipment, Ltd., Cheltenham, and 10 types of Cornmer 7-ton chassis can be modified to either 6 x 4 or 6 x 2 configurations by this company. These % include 11-ft. 9-in.wheelbase and 13-ft. 6-in.-wheelbase models with petrol or oil engines, and four-speed or five-speed gearboxes.
For these conversions, the standard Commer engine, clutch, gearbox, front axle and cab are retained, but the frame is modified. A two-speed auxiliary box is added to some models and Douglas rear axles incorporating Commer finaldrive gearing are used.
The conversions may be carried out to give wheelbases of 12 ft. or more, and gross-weight ratings are dependent upon the tyre equipment fitted, which varies from the standard 8.25-20-in, with twins on the rear wheels to 11.00-20-in tyres on single rear wheels.
With &25-20-in. equipment, the gross rating is 17 tons, and 9.00-20-in. tyres all round raise this by 1 ton. The rating for 11.00-20-in. (12-ply) tyres with singles at the rear is 134 tons, or 15 tons with 14-ply equipment.
The Douglas two-speed auxiliary gearbox is used in 6 x 4 chassis only, and it gives ratios of 2.204 and 1 to 1. Separate propeller shafts drive from this gearbox into each rear axle. The single-drive sixwheelers do not have this auxiliary gearbox, and the trailing axle of these consists of a 41-in.-diameter tube on which are mounted the standard Commer hubs, bearings and brake gear.
A two-spring suspension layout is employed with both types of bogie to give a high degree of articulation, and vacuum-hydraulic or air-hydraulic braking equipment can be fitted, according to the customer's wishes.