New Suspension for York Transfour Semis
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A COMPLETELY new design of sus-. riLpension has been developed by the York Trailer Co. Ltd. for its Transfour twin oscillating axle, 15ton capacity semi-trailers. Instead of the previous layout employing slipper-mounted semi
• elliptic leaf springs with location of the axles by radius rods, the axles are welded in box-section trailing arms and suspension is provided by quarter-elliptic slipper-ended springs mounted to the arms below the axle positions.
Each trailing arm is located through rubber bushings on a tube in a fabricated bracket. Oscillation of the axles is controlled progressively by the compression of the rubber in the bushes, and alignment of an axle can be adjusted by slackening the four bolts clamping the bushing and repositioning it on the tube. The support pads for the slipper ends of the springs are curved so that as load is applied the effective lengths are shortened, so giving a degree of progressive stiffening of the suspension.
Apart from the suspension, the new Transfour is to the same design as the previous model. The main frame longitudinals are parallel-flange 1-section beams of high-tensile steel and measure 10 in. deep by 5-75 in. wide. Full-width cross-members are used from behind the fifth-wheel plate. Standard braking is vacuum, with two-line air or air-assisted hydraulic options. Camoperated brakes are fitted, the four brake units being 15.5 in. by 4.25 in., giving a total lining area of 520 sq. in. Axle
centres are 4 ft. 3.5 in. apart and standard tyres are 10.00-20 (16-ply).
Also introduced by York with the new suspension are "wheel spacers ", which allow offset wheels to be used, providing interchangeability between the semitrailer wheels and tyres and those on the tractive unit. The spacer is bolted onto the hub wheel studs and the wheel is then bolted onto the spacer. By using four spacers the Transfour can be fitted with offset wheels or, alternatively, centre-nave wheels can be supplied and one spacer carried on the outfit instead of a second spare wheel. This will allow the tractive-unit spare to be used on the semi-trailer if necessary.