Automatic Coupling for 24-tonners

24th September 1954, Page 97

24th September 1954

Page 97

Page 97, 24th September 1954 — Automatic Coupling for 24-tonners

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New Scammell Instantaneous Coupling Gear is Air Operated from the Cab and is Foolproof

FULLY automatic instantaneous coupling gear for articulated units of up to 24 tons gross weight is being offered by Scammell Lorries, Ltd., Watford, and be seen in action in the demonstration park at the Lmercial Motor Show today. It is basically a developt of the well-known gear which is fitted to units of up 5i tons gross, but all controls are air-operated and there need for the driver to leave the cab during either 'ling or uncoupling operations. Safety devices make it 3ssible for the tractor unit to he driven away until

er operation. is complete and ensure that the trailer 3ot become accidentally uncoupled.

he tractor portion of the gear utilizes two curved ramps which slide rollers mounted on the turntable of the er. These rollers are located on the ramps by two he rollers which bear on the inside faces of the ramps. [piing is completed by the engagement of a double lockhook on rollers on the underside of the turntable. The k is engaged by air-pressure servo. Spring-loaded buffers lion the impact when coupling. The turntable allows piing and uncoupling to take place over a 180° arc. ecause of the necessity of keeping the centre line of the itable well ahead of the centre line of the tractor driving no attempt has been made to incorporate a retractable ercarriage with the turntable. Pneumatically operated are used instead, and are mechanically locked in both " up " and "down" positions. No wheels have been d to the legs because it is considered unlikely that such irge trailer would be moved other than by a proper tor unit.

he air supply for the legs is automatically connected nigh the turntable when the trailer is coupled and cooled by a valve in the cab. Electrical connections are made automatically. To uncouple the unit a small control lever behind the driver's seat on the right-hand side is operated and passes air into the trailer legs, thus extending them. At the same time, it brings a left-hand control valve into the air-line circuit, and when this is operated the engagement hook is released and the tractor may then be driven away, It is thus impossible to release the trailer without first having lowered the legs. It also means that the driver must use both hands for uncoupling, thereby reducing the risk of this occurring accidentally.

When the legs are down, a mechanical linkage applies the trailer brakes, and these cannot be released until the legs are retracted. This ensures that when re-coupling the unit cannot be moved until the legs have been raised. Warning lights in the cab are arranged to inform the driver when the legs are down and when the hook is disconnected.

Coupling consists solely of reversing the tractor up to the unit and raising the legs, when the vehicle may be driven away. The automatic application of the trailer hand brake, in addition to being a safety measure, also relieves the driver of the necessity of leaving the cab to apply a manual brake lever. The foot brake applies the trailer brakes through a pin in the turntable mitre.

The coupling gear may be applied to existing Scammell 15-ton motive units, subject to modifications to the frame side members, The turntable is also suitable for fitting to existing trailers.