With continued demand for 'call offices' (telephone kiosks) siting the kiosks was more widespred than ever before. A purpose built K6 kiosk trailer was designed to reduce the running costs of cranes.

Introduction:

Various adaptions of K6 trailer have been used from 1953. Fundamentally, the earlier type of kiosk trailer consisted of a pair of pneumatic-tyred road wheels which supported a framework including a pair of rotatable interconnected radius arms. An encircirling clamp was mounted on the extremities of the radius arms for gripping a telephone kiosk above the position of its mass centre. The radius arms were fixed to a large diameter pulley sheave and were moved through an arc of approximately 120 degrees by means of a wire rope passing around the sheave from a hand-operated worm winch. Double-purchase tackle was used to minimise the operating effort required. This method enabled a kiosk to be picked up in its vertical position, as assembled, and placed in an approximately horizontal position on the trailer simply by turning the operating handle. All points of contact between the trailer and kiosk were faced with rubber to prevent damage to the kiosk paintwork. A castor wheel was provided at the forward end and two steady posts at the rear.

Gripping the Kiosk:

During the course of the 12 months in the field, it became apparent that the rubber facing applied to the back bolster and clamping plate were not adequately robust and did not completely prevent movement of the kiosk in the clamping arrangement during the early stages of the lifting action. The transference of the wear to balast strips did little more than mitigate the problem. The clamping arrangement has therefore been modified and simplified to assist manufacture. The elimination of all resilient parts in the clamping members and the use of oak bearing blocks satisfactorily overcame the slipping problem.

After the trailer is placed around a kiosk prior to loading, the radius arms are turned into the appropriate loading position. This is indicated when a white line on the nearside radius arm makes a continuous straight line with the white line on the casing enclosing the worm and gear. This position is of necessity a guide and is accurate only if the trailer and kiosk are standing level ground and the trailer chassis is horizontal.