Extending a Trailer by lift. 6 ins.
Page 68
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ONE of the latest products of the Harrow Industrial Co., Ltd., of Green Lane Works, Stanley Road, South Harrow, Middlesex, is an ingenious extensible pole-carrying trailer, which has been designed to the order of the G.P.O. authorities and is able to transport a 6-ton load. As is the case with all Harrow trailers, this new model has its joints electrically welded. Broadly, the trailer consists of the front bolster frame, the rear bolster frame, the long central pole and the fore-carriage. The central member is in two sections, the outer fixed one being connected at the front at eight points, whilst the rear pole slides inside it, right up to the front of the trailer.
This sliding member is equal in length to the overall length of the outfit and runs on eight rollers, four of which are placed at the rear.' Two of these are horizontal and the remaining two are vertically disposed. A further set of four rollers is situated 6 ft. 3 ins. ahead of this point.
The rear pole is slidably mounted on the aft bolster frame by means of two brackets, and it is secured by a drop n40
head pin having a spring. The forecarriage is attached to the bolster frame by means of the Harrow patent pinless turntable, and a drawbar triangle is fixed to the front axle thnough the medium of hinged brackets. The triangle carries on its forward end a Harrow patent double-acting spring drawbar.
In order to extend the trailer, it is necessary to release two spring-loaded bolts and then the front part of the outfit may be moved forwards. When the bolts engage with holes in the sliding pole the trailer is secure. If it be desired to extend the frame length with
out increasing the wheelbase, this can be done by removing a rear kicking pin and moving the rear bolster frame to any required position in relation to the sliding pole, at the front and rear of which stops are provided.
At the front and back stanchion posts are mounted on hinges and can be swung out of the way in order to facilitate loading and unloading, and are secured by drop-head pins. The loadcarrying bolsters are offset from the axle centres so that, when the pole is extended, there is no tendency for the burden to exert excessive strain in the centre of the trailer.
An unlimited front-wheel lock greatly assists in manteuvring the trailer in restricted spaces.
Intetnal-expanding brakes are operated by means of a hand lever at the front of the chassis, and from the hauling unit through the medium of a Bowdentype coupling. The wheels run on Timken taper-roller bearings and carry 36-in. by &in. pneumatic tyres.
Even when the trailer is extended from its minimum overall length of 21 ft.
ins, to its maximum dimension of 33 ft., it is perfectly rigid.