A GUY
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EIGHT-WHEELED LORRY
An Unusually In teresting Vehicle which is Driven on All Eight Wheels.
WHEN we called at the Wolverhampton, to see the .works of Guy Motors, Ltd.,
new eight-wheel-drive vehicle in action, we first of all journeyed to the testing ground and had a look at the obstacles over which the machine was to perform. Our first summing up after the inspection was—" utterly impossible." A few minutes later, however, it was realized that yet another step forward has been made by mechanical transport, for trenches 5 ft. wide and 4 ft. deep, quagmires over a foot deep and freakish surfaces were negotiated with perfect serenity by the huge 10-ton machine.
"Will Do Almost Anything."
With only the rear wheels driving, the vehicle will do almost anything, but it is possible to find a surface so soft that the driving wheels will spin--in other words, an ordinary six-wheeler would be bogged. So soon as the driving mechanism to the four front wheels is engaged, however—a simple operation effected by moving a lever conveniently placed to the driver's hand—sufficient tyre grip is assured and the vehicle can move off without a trace ofskidding or wheel-spin. c2
As might be expected with a bogie at both the front and the rear, suspension is well-nigh perfect on any surface comparable with that of a first or second-class road. Each of the front axles is mounted on offset semi-elliptic springs, a balance beam, which forms the interconnecting medium, being so arranged that its angular movement is restricted by a thoroughly substantial stop.
In this way either of the leading axles is capable of carrying the load imposed on the front of the vehicle, and consequently trenches of slightly greater width than the pitch of the two front axles can be negotiated without upsetting the equilibrium of the vehicle. At the rear the more familiar bogie arrangement is utilized, each axle being mounted at the extremity of a pair of inverted semi-elliptic springs which swing from a trunnion situated midway between the wheels. Again, the articulation of the axles about the trunnion is limited, so that the same results are obtained when the rear wheels negotiate a trench. Some of the details were dealt with in patents described in our issue dated June 10th, 1930.
How the Wheels are Driven.
The driving arrangements are indicated in the diagrammatic drawing of the front of the vehicle. A short shaft running from the -gear
box terminates in a spiral-bevel gear which, engaging with a further bevel gear on a cross-shaft, transmits the _drive to wortn gears fitted at each extremity of the cress-shaft Thereafter short universally jointed shafts convey the drive to further worms and worm wheels on each side of the front axles; finally, the wheels are rotated by spiral spur gearing located in casings attached to the wheel hubs.
The drive to the rear is effected in more or less normal fashion, allmetal universally jointed propeller shafts being employed in conjunction with fully floating worm-driven axles.
Special Radius Antis Fitted.
As really high torque figures are attained, the reaction from the front wheels cannot be taken through the springs. Consequently, special radius arms have been fitted at a height just above the frame level; these are so arranged, of course, that a parallel-link motion is achieved in order to avoid steering " fight."
As will be seen from the drawing, the arrangement of links, etc., between the steering-box and the wheel pivots is very simply carried out. The usual drop arm from the
Manes box has been reversed and the drag links run fore and aft from this arm.
Some idea of the size of the vehicle may be obtained when it is stated that the wheelbase measured from the centre line of the front axle to the centre line of the rear liogie is 13 ft. and the tracks 6 ft. 44ins. and 6 ft. 3 ins. at the front and the rear respectively.
Despite the complication of four wheels instead of two at the front, a body length of no less than 10 ft. 10t ins, is available, although the frame length is but 21 ft, 4 ins.. The overall dimensions work out at 23 ft. 3 ins.
and 7 ft. 5i ins, for length and width respectively, whilst the vehicle is capable of dealing with 5 tons, including a winch gear, when running on hard . roads.
We can now turn to a consideration of the power-unit and other features of the design. A six-cylindered engine of 4i-in.
bore and piston stroke is used and it develops 55 b.h.p. at 1,000 r.p.m„ 81 b.h.p. at 1,500 r.p.m. and 96 b.h.p. at 2,150 r.p.m. at the flywheel. The design embodies the familiar form of Guy combustion chamber, in which the valves lie alongside the cylinders, but with their stems steeply inclined so that a compact explosion space is provided.
Cooling is assisted by a centrifugal pump, and the water is circulated through a Still-tube radiator.
A comprehensive lighting equipment is also to be found in the specification, the dynamo and battery being of sufficiently large capacity to work an electric starter.
From the flywheel a single dry
plate clutch transmits the drive to an independently mounted gearbox, which provides four speeds forward and a reverse; the ratios of this box are 1.73, 3.62 and 4.99 to 1 for third, second and first gears respectively.
The Auxiliary Gearbox.
Behind this unit an auxiliary set of gears provides a direct drive, an indirect reduced speed, and incorporates the drive to the front axles, as well as an auxiliary countershaft for a winch. The reduction on the indirect gear is 3.38 to 1, which, taken in conjunction with the main gearbox, gives eight speeds, with ratios varying between 7.33 to 1 and 123.9 to 1, the corresponding road speeds at an engine speed of 1,500 r.p.m. being 22.87 m.p.h. and 1.35 m.p.h. respectively.
All brakes are of the internalexpanding type, operating on only the rear wheels; a vacuum-servo motor is cOupled to the pedal, giving good braking pressure.
Lastly, it should be mentioned that a winch, manufactured by Herbert Morris, Ltd., of Loughborough, is provided ; this gives a maximum pull of 7 tons, with a drum capacity for 250 ft. of cable. The winch drive is laid out in such a manner that the whole of the available four speeds of the main gearbox can be utilized for winding, and fair leads, capable of transmitting the pull to the rear or to either side of the chassis, are provided.