ACROSS COUNTRY with an
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OIL-ENGINED SIX-WHEELER
FoR OGRESS relating t c the o m pr essiono ignition engine and its application to road transport is indeed rapid, and the latest hails from the works of Crossley Motors, Ltd.,Manchester, whe re a rigid sixwheeler incorporating the well-known Crossley six-cylindered oil engine has been produced.
Although new in the sense that such a vehicle has never yet been sold by the Crossley company, the chassis is almost identical with the design produced in large quantities for Government work. and the engine is a repliei of the successful unit used in Crossley passenger chassis. It is the combination of the engine and chassis which is really the innovation.
Forward control has been incorporated in the layout in order to provide a maximum platform length on a chassis with a 12-ft. 10-in. wheelbase. The bogie-axle centres are -3 ft. 8-I ins. apart, whilst the wheel tracks, with single tyres, are 5 ft. 51 ins, front and 5 ft. 2 ins. rear.
For cross-country running the Dunlop 40-in. by 9-in. tyres on the driving wheels were encased in chain tracks of the usual War Office pattern. Otherwise, the vehicle was of normal layout and was laden with 3 tons of ballast.
Quite a usual front axle of H-section between the spring pads and round section at the extremities is used and is suspended on semi-elliptic springs. At the rear, dual inverted semi-elliptic springs are employed and the movements of the driving axles are controlled by radius arms which serve the purpose of taking care of the driving and braking torque reactions. Both frame side members are of alloy steel formed into channel-sectioned pressings ; they are braced by five channel cross-members, together with tubular ties which form the rear bogie mounting. Towing loops
are provided fore and aft, It would be invidious to pass over the power unit, despite the fact that it is by now well known, without giving a few particulars regarding its design and capabilities. Bore and stroke dimensions of 4* ins, and 6 ins. respectively give a capacity of 556.7 cubic ins. (9,120 c.c.) and an R.A.C. rating bf 47.3 h.p. The power output is now greater than ever, being 71.4 b.h.p. at 1,000 r.p.m. and 100 b.h.p. at 1,800 r.p.m., at which speed a governor cuts in. The cylinders are cast in one block, with renewable liners inserted from the upper end.
The cylinder heads are formed in two blocks of three and incorporate vertically disposed overhead valves which are operated by push rods and rockers from a camshaft contained in the crankcase. All seven bearings of the balanced crankshaft are fed with oil from a fullpressure system, which incorporates a dry rump and an oil container suspended below the after portion of the crankcase. A second.oil pump exhausts the crankcase so that there is no possibility of
any section of the engine being flooded with oil even if the vehicle be negotiating extremely uneven ground.
Starting is effected by an electric motor with a Bendix drive on to a geared ring built in the flywheel, a compression release gear being incorpol-ated in the layout of the valves in order that the motor can rotate the crankshaft at sufficient speed to overcome the resistance of two or three initial compressions.
A single-plate clutch with Pero& driving discs incorporates a multi-spring pressure plate and a springloaded clutch stop, the drive between the free member of the clutch and the gearbox being effected by means of a fabric universally jointed coupling shaft.
Fight gears are provided, the normal range covering ratios between 25.01 to 1 and 5.75 to 1. An auxiliary "second reduction" gives ratios between 79.52 to 1 and 18.28 to 1, with a reverse ratio of 68.19 to 1. Thus, for ordinary road work, the normal gearbox should do everything which is required, whilst when negotiating colonial ground the " extra-low " range shonld enable the vehicle to tackle any gradient on which the driving wheels can obtain a grip.
We will now turn to a consideration of the manner in which the vehicle behaved during a strenuous test last week. The proving ground itself is high up in the moors between Glossop and Hayfield, and the surface at the time of our visit had been softened by the recent heavy rains, whilst in many places the ground had been cut up by other vehicles undergoing their tests. Conditions were, therefore, about as bad as could be, and, when it is considered that gradients as steep as 1 in 3 to 1 in 4 were successfully climbed without apparent effort, the capabilities of the vehicle for cross-country work can be appreciated.
From the main road a long climb of a gradient of about 1 in 7 proved to be no test at all, for the vehicle Merely played with its work and stopped, restarted and manoeuvred according to the whim of the driver. Farther up the hill, where the specially prepared " sticky sections" were located, the demonstration was even more convincing, for the driver would essay a short, sharp incline of perhaps 1 in 4 and would stop in the middle of it for photographs to be taken, afterwards continuing quite unperturbed. Making a long circuit around the moor, quite a surprising speed was maintained, and although the top gear of the higher ratio series was never engaged, the onlookers heard little gearbox" noise. The engine, too, behaved unobtrusively and, except at times when the accelerator pedal was suddenly forced down, the exhaust was almost devoid of smoke.
A noticeable feature which should prove to be most desirable ip a vehicle of the type under review is that the engine will "tick over" steadily at an inordinately low speed without misfiring or giving one an impression that it is likely to peter out at any moment. During the test the engine was left turning over slowly for quite long periods an d immediately responded to a flick of the accelerator pedal so soon as it was, desirable to move off.
The brakes worked Perfectly and, what is most important, were capable of pulling up the vehicle when it was travelling either forwards or backwards even on gradients as steep as 1 in 4: This is indeed excellentBoth the hand and foot systems are of the internal-expanding type operating in drums on all four rear wheels, providing four-wheel braking by either hand or foot.