A New Semi-trailer
Page 57
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ANEW semi-trailer is shortly to be produced by Biflex Trailers and Tractors, Ltd., 1, Shortlands Road, Kingston-on-Thames. Its design incorporates certain novel features which, it is claimed, insure its safety at high speeds, provide for flexibility between tractor unit and trailer, and eliminate distortion of the chassis frames.
We understand that the trailing unit can be uncoupled from the motive unit in under one minute, and that its manceuvrability when detached is extremely good.
A 3-in, cast-steel ball forms the kingpin; it is supported by two steel rocking arms provided at their outer ends with steel rollers, which run on the turntable ring, mounted on the frame of the motive unit. The rollers are kept in contact with the turntable by a flat laminated spring, situated on top of the rocking arms, the action of which is to keep the wheels of the trailer and tractor on the ground when cornering or when the road surfaces on which the driving wheels and trailing wheels are running are not parallel.
The socket in which the king-pin works is mounted between two laminated springs working in a horizontal plane and set transversely in a subframe on the chassis of the towing unit. These absorb braking and tractive shocks. A locking device controlled by a rod from the near side of the vehicle releases the king-pin when it is desired to separate trailer from motive unit. The turntable is 3 ft. in diameter and is mounted on a channel-steel frame which, it is stated, can be conveniently fitted to any type of commercial vehicle. The frame of the trailer is of pressed steel having six crossmembers and the rear axle is of solid square-sectioned 50-ton-tensile steel ; semi-elliptic springs are used. The brakes are of the Lockheed hydraulic type, and the wheels are shod with 32-in. by 6-in, heavy-duty pneumatic tyres. The Biflex semi-trailer is available with a straight frame or with dropped members to give a low loading level, The undercarriage of the trailer frame carries a pair of jockey wheels having Ackerman-type steering. They are lowered, by hand, through a worm and nut to take the weight of the front portion of the trailer when detached.
To facilitate the attachment of the trailer to the towing unit, a short ramp is provi led to guide the rollers on to the turntable.
The straight-frame model is made in two lengths, 17 ft. and 23 ft., the width being 6 ft. 6 ins. On the droppedframe model there is a space of 6 ft. over the turntable, and 16 ft. from the drop to the end, the width in this case being 7 ft. 6 ins.; the distance from the floor to the ground is 1 ft. 6 ins.
We understand that the price of a straight chassis suitable for carrying 3-4 tons is £125, whilst the low-loading type built for a maximuni load of 6 tons costs £200. The price of the undercarriage and jockey wheels with steering gear is £12 12s.