Timber-carrying
Page 136

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by Special Trailer
ACOMPANY which has for, some time past specialized in the construction of special types of trailer is Cranes (Dereham), Ltd., South Green Works, Dereham, Norfolk, and one of its latest products is the pneumatictyred timber-carrying trailer which is illustrated on this page. The use of pneumatic tyres on a unit of this class offers distinct advantages, for when negotiating soft ground the area of contact is so considerable that sinkage is unlikely, whilst, when the trailer is being run on a metalled road a high speed is permissible.
The trailer is provided with bolsters at the front and the rear. To the front bolster is attached the steel pole, made from two channel members, forming a box-section which gives great strength. The rear bolster is made adjustable on this so as to Cary the length. A standard type of forecarriago is employed with" the front bolster and the drawbar is made with a pivoting eye, so as to avoid undue stress when travelling over rough ground.
Each bolster has a chequer-plate top to facilitate the use of a pinch bar and to give a grip for the load. Removable stanchions are provided, as well as brackets for taking ramps to relieve the tyres of the weight of tree trunks when
loading is in operation. These are designed so as to obviate dangerf.in removing the bolster pins when unloading is being carried out. They can be mechanically removed by the pins supporting them 'being withdrawn by the tractor. Special precautions have been taken to exclude mud from clogging between the twin pneumatic-tyred wheels.
The internal-band brakes on all -four wheels can be operated by hand lever from the forecarriage, from the tractor, and from the rear carriage by means of a hand-wheel and screw, steel 'cables being used to transmit the action.
The springs are underslung to give a Jew-loading height and are sufficiently strong to withstand an overload. Stops on the springs eliminate shearing stresses on the bolts. This. is an important feature, as timber trailers suffer severe shOcks .when travelling over exceedingly rough ground.
The wheets-h.ave taper roller bearings and are equipped with 40-in. by 8-in. pneumatic tyres. The trailer is constructed of steel throughout. A useful bar is fitted' at the rear for carrying chains, whilst hooks are provided at convenient points for securing the load by means of chains or ropes.
Trailers Of this description are largely used in conjunction with Latil tractors, and it may be said that the combination is ideally suitable for forestry work, even on very soft ground surfaces.