Six-wheel D1000s: Conversions by Primrose
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THIRD axle conversions are already being offered by the Primrose Third Axle Co. Ltd. for the Ford D1000 16-ton gross fourwheelers announced last week. When converted into rigid six-wheelers in this way the Ford D1000s have plated gross weights of 20 tons or 22 tons according to the wheelbase.
Either single-drive or double-drive bogies are available, the added weight being approximately 24 cwt. and 28 cwt. respectively (there are small variations dependent on the wheelbase). The list price of a single-drive conversion is £745, and of a double-drive model, £1,420—when 10.00-20 tyres are specified.
Chassis frames are extended by 12 in. deep and in. thick pressed steel channel sleeving the original side-members from a point ahead of the shackle brackets of the front springs. Full-depth cross-members are used so that maximum torsional stiffness is obtained in addition to the
extra bending strength afforded by the sleeving.
Four-spring balance-beam bogie suspension is used. With single-drive bogies the balance beam is offset so that more weight is carried by the driving axle than the trailing axle, the ratio being 7 to 5. Where extra traction is needed the Primrose Hi-Lift load-transfer device can be specified. Double-drive bogies have a 1 to 1 balance-beam ratio, which allows 9 in. more body length than those recommended in the Primrose leaflet for single-drive conversions.
The added third axles have 10-stud hubs and cam-expanded brakes. Single-drive models have 7 in. wide brakes. Double-drive models have 6 in. wide brakes.
Dual chamber diaphragms are fitted to the Primrose third axle, One chamber is linked with the brake chambers of the Ford rear axle and the other chamber is linked with the primary chambers of the front-axle's dual brake units. Thus, which
ever side of the Ford split footbrake system should fail, the brakes of the trailing axle will always operate. If the whole footbrake system should fail there is still the power-assisted handbrake and the secondary chambers of the front brakes.
A Primrose conversion lengthens the wheelbase of any Ford D1000 model by 2 ft. 2 in. For 20 tons gross, six-wheeler wheelbases of 12 ft. 2 in. arid 14 ft. 5 in. are recommended. These afford tipper body lengths of 16 ft. and 18 ft. 6 in. respectively. A 22-ton gross tipper is included in the range of Primrose D1000s. It has a wheelbase of 15 ft. 11 in., which brings the outer-axle spacing an inch beyond the legal minimum required to qualify for 22 tons gross. A body length of 21 ft. 8 in. is advised.
For haulage work at 22 tons gross, wheelbases of 17 ft. 10 in. (giving a body length of 24 ft. 9 in.) and 19 ft. 4 in. (allowing a 27 ft. 2 in. body) are offered.