A demountable that's different
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by Ron Cater • A new self-centiing demountable body has been announced this week by Ronway Engineering, an offshoot of Ronway Transport.
There are several novel features embodied in the design which is thought to be the first of its type that is completely self-aligning and which can be mounted or removed without the need to ensure that the carrying vehicle is perfectly straight beneath the body.
A sub-frame is mounted on the vehicle chassis and this is ramped at both ends, rising and falling a total of 2in. At the front end of this frame there are two locating and securing lugs. Towards the rear of the frame, and situated in the top flange, there are two recesses machined into the surface and designed to accept the treads of the body rollers. One-inch high guide-flanges are built up on the insides of the tracks and at the rear end these are tapered both downwards and inwards to form leads for the rollers.
A pair of electro-hydraulic jacks are situated between the main frames at the rear: they provide for a total lift of 6in. The body is fabricated from two rolledchannel main members with pressed steel cross-bearers and side raves. A I.25in. nominal thickness hardwood floor is fitted. At 'the front of the body a pair of rollers 8in. in diameter and with 3in. tread are mounted in outside frames and carried on separate spindles. These rollers are set, so as to run on the top flange of the chassis sub-frame and on the outside of the guide flanges. When landed the body is supported by four swinging and extending legs. Two height settings are provided for and the legs telescope. and hinge up to park beneath the body while, on the road.
The main feature of the design is a fifth-wheel-like plate mounted between the rear ends of the chassis sub-frame members and a vertically swinging A-frame which carries a king pin. It is this equipment which allows the chassis to be placed under the body without the need for ultra-accurate positioning for the chassis plate has a tapered lead which provides for a lateral location of the body over a distance of 7in. either side of the centre-line. In practice the laden body—being heavier than the chassis —causes the rear wheels to slide sideways sufficiently for the alignment to be achieved.
The two recesses in the chassis sub-frame members mentioned earlier are designed to assist the driver to locate the body in a position allowing the hydraulic lifting gear to be brought into action for the purpose of raising the body sufficiently for the support legs to be lowered or raised. When the rollers have been landed on the chassis the vehicle is reversed to a point when the locating laws centralize the chassis. This takes place quite automatically and without stress on either the body or the vehicle because at that stage the load is being carried mainly by the front axle and the rear support legs of the body. When it is fully home on the chassis, the body is raised off its support legs by the hydraulic jacks and, once the legs are stowed, the jacks are lowered. As the body runners come into contact with the top flanges of the chassis sub-frame, two spring loaded locks snap into position and the body is securely located.
The jacking system is powered both up and down, the operating lever being connected to the securing locks via a Bowden cable so that there is no chance of the body being raised without the locks being retracted.
The total operating time cycle to demount and remount the body is 4min.
A total weight of 2,340 lb is achieved on the prototype which has been in continuous service on day-to-day operations for six months. The cost of the unit with a 20ft long platform body is £860. Manufacturers are Ronway Engineering, Manor Works, Western Road, Southall, Middlesex.