VEHICLE Design of Vehicle in Which the Load is
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A ramp and quick-acting coupling are provided, and a handle on the towing pillar is used for raising the front end of the drawbar so as to transfer part of the load to the motive unit. Normally, about 2i tons is thus superimposed. The towing pillar is a few inches in front of the driving axle, so that about a seventh of the superimposed load rests upon the front (steering) wheels.
The angle of the ramp ensures that some load is superimposed, even if the driver forgets to turn the Ii an die.
The result is, in effect, a multiwheeled outfit having two points of articulation in the horizontal plane —one at the towing pillar, the other at the turntable. As the front wheels of the carrier unit are but (3 ft. 3 ins, behind the driving wheels, the advantages of load Superimposition are reaped to the full. The outfit is extraordinarily secure. Jr steering, the four tractor wheels act like the leading bogie of a locomotive, and, because of the load upon them, they are followed safely by the carrier-unit wheels.
A recent improvement in the drawbar further enhances the performance. The new drawbar passes through a trunnion block located near the rear edge of the turntable, permitting it to pivot in the vertical plane, or to be drawn forward through the block. The front of the turntable hangs from the drawbar by means of a link or shackle, so that forward motion of the drawbar causes the front end to move downward through an arc.
Plainly, the greater the drawbar pull, the greater will be the downward pressure of the drawbar upon the motive unit. When a gradient is being climbed, therefore, the amount of load superimposed
automatically increases. When drawing out of a sand pit, with the four rear carrier wheels sunk, perhaps, axle deep, the driving wheels get well under way before the carrier unit commences to move, and the smooth take-up of the pull, with the increasing downward pressure on the driving wheels, greatly. facilitates extrication.
When passing over a hump-back bridge, with carrier unit ascending and motive unit descending, the drawbar, by moving forward and downward, accommodates itself to the lower level of the towing pillar —without reducing the amount of load superimposed.
All these unique' Beardmore fen. tures are quickly appreciated in the course of a test such as we have undertaken. The steering is exceedingly light, yet, for reasons above explained, reliable. The whole outfit performs as a unit on the road, and there is a complete absence of the snaking tendency and the bucking common with trailers. The controls are comfortable to handle, and the clutch works sweetly ; we were able to start from rest in fourth gear. The engine and transmission are free from undue vibration. The latest cab has Celotex-lined floorboards, neat tool accommodation under the floor and a good double screen. . Braking is of foremost importance, because of the vehicle's weight and speed capabilities. The important wheels for braking are the four at the rear of the trailer. These are braked by two Westinghouse vacuum cylinders of 8 ins, bore and 8 ins, stroke, each acting, through a balance bar, upon one pair of wheels. Excellent compensation and power are obtained, and no effort is needed In operating the ratchet-type control lever mounted on the dash. There is a slight time lag, but this is not serious. The Westinghouse reservoir system permits four or five applications withthe engine stopped. It is futile to apply the drivingwheel brakes without the carrierunit brake, but, once the latter is "on," application of the transmission and wheel-drum brakes on the driving wheels hasgood effect. In practice, one gets to rely on the power brake for all ordinary retardation and uses the other brakes additionally in emergency. Manual application of the carrier-unit brake Is available for parking.
The fact that the road was wet enabled us to verify that the comparatively heavy load on the rear
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ance in this respect, the top-gear ratio of 7.14 to 1 resulting in fuel economy on level stretches and when travelling light. One important advantage to the average speed, economy, etc., is the fact that, due to the general security, momentum gained on dewending one hill carries one up the next.
We climbed the notorious Reigate Hill, in Surrey, from the corner of Birkheads Road to the bus stop on the left at the top, 1.2 mile, in 141 minutes, averaging 4.9 m.p.h. in first gear. At the summit the coolingwater temperature was 166 degrees F. (air temperature 46degrees). The claim that it is cheaper to haul than to carry is borne out again in the fuel-consumption and tyre wear. The fact that the unladen weight is so low, of course, means that the figure of pay-load ton-miles per gallon of fuel is high in proportion to that of gross-ton-miles.
We covered 241 miles from Honey into London, including climbing Reigate Hill, at a consumption rate of 4.41 m.p.g. The severe climb and our high average speed suggest that a higher figure would be obtained under ordinary working conditions. The Solex type-40MOHGTL horizontal carburetter was found to have the followingsetting : Main jet 175,dpilot jet 65, choke 36.
The low tractive effort required on the driving wheels, together with the fact that they are not overloaded (for overloading accelerates tyre wear), results in tyre economy. This is testified by many users of multi-wheelers of this particular kind. The trailer tyres, also, because they trail naturally, with no side dragging, and are of the lowpressure type which retain a rolling contact over irregular surfaces, and do not bounce, last very well. The trailer used for our test had covered about 20,000 miles and the tyre wear was almost imperceptible. In conclusion, this ispe a high-capacity vehicle having peculiar advantages, especially in the matter of economy, and being well suited to long-distance work as well as to short hauls, in whichcarrier units , are changed quickly at the termini. The address of William Beardmore and Co., Ltd., is Park Crescent, Clapham Park Road, London, S.W.4.