All-steering axles slash cut-in
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• Mechanically steered semi-trailer axles which increase manoeuvrability and reduce tyre scrub are featured on a new semi-trailer designed by Mr. G. Hoy, managing director of Hoynor Ltd., of Danbury, Essex. A 60ftlong version of the new Hoynor True Track trailer with three 8-ton mechanically steered axles was demonstrated last week at the FVRDE, Chertsey. The axles give full Ackerman steering, operated from the fifthwheel coupling by means of a V-plate mounted on an inverted king-phi which arcs through 180deg from a pivot point centred in the jaws of the fifth-wheel coupling. This pin is connected to a bell-crank and linked to the main steering, which in turn is linked to each axle.
The trailer is available in lengths of from 40ft to 100ft and is eminently suitable for carriage of indivisible loads. It can be supplied with one, two, three or four axles according to the operator's requirements. The 60ft model, which weighs 7 tons lcwt, is designed for use at a gross combination weight of up to 44 tons.
Demonstrating the degree of control achieved with the steering axles, two outfits —one with fixed axles, the other steered— were driven around a marked-out circle. This showed that while the cut-in with the fixed axles was considerable, the steered unit tracked more or less on the line taken by the driving wheels of the tractive unit.
Also showing how much control could be applied to the rear axles, the trailer was driven round a sharp left-hand corner on a down gradient. During this test the wheels hugged the nearside edge of the road all the time—no mean feat when one considers that the driver was some 60ft from the tail of the vehicle.
Perhaps the most spectacular of the tests was the final one. For this the trailer was driven over the pave and the driver (Mr. David Burton—a finalist in last year's LDOY competition)—came out of the test looking a great deal less composed than his vehicle.