Novel Features in a
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New 30-cwt., Articulated Outfit
Named the Petrol Pony, this New Articulated Outfit is Designed for 30-cwt. Pay-loads. The Three-wheeled Tractor is Built on the Tubular-frame Principle and the 7 h.p.four-cylinderedEngine is Rear Mounted APILY named the Petrol Pony, a new light articulated ouita, designed for 30-cwt. pay-loads, has recently been placed on the market. A new company is being formed to manufacture the machine, and the marketing arrangements are in the hands of Frank Waring, Ltd., 38, Great Portland 'Street, London, W.1.
As will be seen from accompanying illustrations, the tractor unit is of the three-wheeled variety, and the fourcylindered engine is rear mounted. The construction of the chassis is on the tubular-frame principle, and the main member comprises a tube of 31 ins, diameter, which has a forked casting at its forward end. This casting carries a curved radius arm upon which is mounted the stub axle for the single front wheel.
The front suspension is by a laminated spring, and it works on the cantilever system. The forward end is bolted to the radius arm, and the rear end slides between two hardened-steel bolts, which pass through the tubular frame. Steering is effected through a drag link connected to the drop arm of a Burman-Douglas steering gear, which is mounted on the body.
At the rear end of the tubular-frame member is mounted the transmission unit, which incorporates a Burman three-speed constant-mesh gearbox, which is attached transversely to the casing of the transmission unit at its forward end. A spur-driven axle is disposed centrally in the casing, whilst at the rear is mounted the clutch and the four-eylindered power unit.
The engine is a 7 h.p. Austin, and the bell-housing which accommodates the clutch is bolted directly to the rear, facing of the transmission unit. A subframe is attached to the engine crankcase and upon this is carried the rearmounted radiator. Two stays are provided for the sub-frame so as to ensure the rigidity of the radiator mounting.
Having a bore and stroke of 56 mm. and 76 mm. respectively, the power unit has a capacity of 747.5 c.c., and it is rated at 7.8 h.p.; the maximum output is 13.7 b.h.p. at 3,400,r.p.m.
The drive is taken through a singleplate clutch to a shaft which passes beneath the axle crown wheel. On its forward end, this shaft has a worm meshing with a worm wheel mounted on the end of the gearbox shaft. From the gearbox the drive is transmitted through a pair of spur gears back to the differential, thence by two open
shafts, equipped with Hardy-Spicer universal joints, to the rear wheels. The first reduction on the worm drive is 31 to 1, and on the final spur drive the reduction is 2-1to 1.
As previously mentioned, the gearbox is of the constant-mesh pattern, and a novel type of gear-change mechanism is incorporated. The gears are actuated by a series of dog clutches, and the lever is moved, from a central position, backwards or forwards, as the case may be, for upward or downward changes, until the movement is arrested by a stop. The principle involves the use of a double-acting pawl and ratchet. The movement of the lever is transmitted to the selector mechanism, which effects the actual change; when released, the lever is returned to the central position by means of springs.
Gear operation becomes, therefore, a simple matter because, to make upward changes the lever is merely pulled hack, and, as each change is made, it returns to the central positionTo change down, the lever is pushed forward, in a similar manner.
Since it is necessary in every .case " to go through the gears," in order to select the " neutral" position, an indicator is provided on the dashboard. This comprises a series of lights—one
for each gear—so that the driver knows at all times which gear is engaged. The movable arm, on the side of the gearbox, is arranged to pass over a contact as each gear is engaged, and these contacts are connected to the lights on the dashboard. The indicator operates only when the ignition switch is on.
The rear suspension is effected by two transverse springs, one being mounted above and the other below the transmission-unit easing. At the outer ends, the springs are accommodated in Silentbloc bushes in brackets which form the housings for the bearings carrying the hula shafts and the brake-plate anchorages.
A ball coupling is used for the semitrailer connection and the tractor portion of the coupling is carried in a casting mounted on a base plate above the top spring pad.
Dendix brakes are provided on the two rear wheels of the tractor, also on the trailer wheels, and both foot and hand means for control are available. Operation from either the pedal or the hand lever is by means of rods to a short cross-shaft set amidships above the tubular-frame member. TWO cables then transmit the pull to the tractor wheels, a third cable, passing over a pulley, leading to a screw connector on the forward end of tho semi-trailer brake cable.
The engine is, of course, bonneted, and a comfortable cab of light but sturdy construction is provided.
Of the two-wheeled type, the -semitrailer has a platform length of 20 ft.; the width of the floor is 4 ft. 8 ins. The frame is made up of two girdersection side members, adequately braced by tubular cross-members and two diagonal members. The suspension is by half-elliptic springs, mounted on Silentbloc bearings at the front ends ; the rear ends slide in trunnions.
All wheels are interchangeable, and they are equipped with 4,50-18 tyres, The semi-trailer axle is dropped, and the loading height is only 1 ft. 9 ins.
Approximately one-third of the weight of the load is superimposed on the tractor, and the unladen weight of the complete outfit is 17 cwt. The motive unit weighs 10i cwt. and the semi-trailer turns the scale at 6-} cwt.
We understand that the performance of the machine has exceeded the maker's expectations, and its handiness should make a wide appeal for certain classes of work. The outfit is priced at 195 for the tractor with trailer chassis and, in the near future, a vantype semi-trailer will be availa.ble, in addition to the model illusfrated.