To Facilitate Trailer Manoeuvring
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Ingenious Dyson Device by Which Turntable Can be Rotated With Ease and Precision by the Operative From the Side of the Trailer
QCOPE for the exercise of considerable skill is afforded L./when a four-wheeled trailer has to be manceuvred with accuracy into a given position. In the past a number of means has been adopted for rendering operations of this description easier, but the difficulties have not been wholly
removed. , R. A. Dyson and Co., Ltd., 76-80, Grafton Street, Liverpool, 8, has recently evolved a device by which the front undercarriage of a turntable-type trailer can be swivelled through a limited angle, by means of crank, handles worked by an operator standing 'on the ground beside the vehicle. This arrangement enables him to steer the trailer easily and accurately while it is being backed or, if required, while it is travelling forwards. An accompanying picture shows the trailer, which was built by the company to carry a showman's van, and designed with an eye to the fact that it would frequently have to be manceuvred in confined spaces. A sketch explains the details of the mechanism. It will be observed that a shaft runs, for practically the full platform width, across the front of the vebiele. It is threaded for most of its length, the screwed part being within a U-section tube. Upon the shaft is a nut on which is formed a pin carrying a roller. The last-named protrudes through the slot in the tube, which acts as a transverse guide, and is free to move axially when the shaft is rotated, this being effected by a handle from either end.
Upon the undercarriage front is fixed a longitudinal guide for the nut roller. Thus, rotation of the turntable is caused by axial movement of the nut.
Clearly, it is essential that free movement be permitted under normal conditions, and to achieve this end the slotted tube is turned through 90 degrees, so that the roller-pin is brought from a vertical into a horizontal position. This is accomplished by inserting a tommy-bar into a radial hole in a ring welded to the end of the tube while releasing the ring by pulling out axially the spring-loaded bolt shown, in the drawing, in detail.
Of 7 tons capacity, the trailer is not without general interest. Its platform level is only 2 ft: 11 ins., the tyre size being 27 ins. -by 6 ins., and Dunlop equipment being used. There is a ball-bearing turntable and the brakes are Girling products.