Cranes Modify Bogie Suspension
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riA NEW type of trailing-arm bogie suspension has been developed by Cranes (Dereham), Ltd., for their I6-ton semi-trailers. The new system supersedes the present type, essential differences in the new design being that the bearings are carried in the radius arms, instead of there being journals on the arms, with the bearings in brackets. The radius arms themselves are more robust and the box section has been made wider to give added resistance to side thrust.
Ferrobestos bushes and thrust washers are used instead of self-aligning bearings and hardened bushes and pins. Not only does this arrangement eliminate the need for lubrication, but it is claimed also to damp down wheel movement, thereby dispensing with the need for suspension dampers. There is a through cross-shaft the full width of the chassis frame, and this is supported by three brackets, whilst the rear radius arms are continued forward of the pivots and clamped to the springs with specially shaped extension pieces which rest on the springs to give a progressive action, taking effect on both bogie axles.
Two types of brake are offered with this new bogie. Both are l51-in. by 6-in. assemblies, the choice lying between Girling wedge-action equipment and Rubery Owen S-cam units, the two different types being interchangeable. Air-pressure actuation is employed with either type of brake. Tyres ranging from 8.25-20-in. to 11.00-20-in, can be installed without any modification and without changing the standard 5-ft. 8-in, track.