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Special War-tim eeds Met By New Guy Double-deck Chassis

28th August 1942, Page 24
28th August 1942
Page 24
Page 25
Page 24, 28th August 1942 — Special War-tim eeds Met By New Guy Double-deck Chassis
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New Model of Arab 56-seater Which Reflects Maker's Efforts to Meet Present Economic Needs Whilst Providing the Good Service Operators Customarily

Expect from 'Guy Products

BIIILT to meet war-time requirements, a new version of the wellknown Arab double-deck chassis is announced by Guy Motors, Ltd., Fallings Park, Wolverhampton. It has been constructed under instructions from the Ministry of Supply toa specification agreed between the Ministries of Supply and War Transport and the Technical Committee of Operators. A reputation for longevity was enjoyed by the pre-war prototype, many Arab buses having completed mileages approaching the half-million mark during their working lives, and it is unlikely that any of the modificaticms embodied in the new model will . detract from this characteristic, as they relate mostly to simplification and the elimination of light metals.

Resulting from • the latter is an increase in the chassis weight of 18.5 per cent., and, unfortunately, it has not been possible to raise the power available in accordance with the weight, in order to provide so good a pi:aver-toweight ratio as formerly. The maker would have liked to have itistalled a Gardner six-cylindered engine, but the Ministry of Supply Stipulated the 5LW —at least, in the majority of cases.

. An additional factor that will affect performance is that a larger number of standing passengers is now allowed. Readers will remember that this fivecylindered oil engine, which has a piston displacement of 6.974 litres, develops 85 b.h.p, at 1,700 r.p.m. and , exerts a maximum torque of 28( lb.-ft. at 1,000-1,100 r.p.m,

A feature that promotes all-round efficiency, particularly in public service vehicles is the use of a double plate clutch. This unit, moreover, is of the open type, a . point that is usually appreciated in the repair shop, and an interesting detail is that the four friction facings are not riveted to the discs, the idea being to keep down the weight of the spinning member_ Mounted roughly amidships, the gear

box is supported on rubber cushions at three points. All gears are ground and canberemoved without detaching the box. It affords -ratios of 1,1.7, 2.86 and 4.6 to I forward and 4.4 to 1 reverse, whilst the final-drive ratio may be 6.25. or 5.6 to 1. Gear changes are effected by a lefthand lever, Hardy Spicer needle-roller universal joints being incorporated in the remote-control shaft.

In the main transmission line, four Layrub rubber-cushioned joints are used—one pair in the front propeller shaft and another pair in the rear—and both shafts are balanced.

An underslung worm drives the fully floating axle shafts, the unit being offset to the near side. The worm and wheel centres are 8 ins, apart and the axle casing is a basin-type drop forging. At the rear end the worm shaft is carried in double tapered-roller bearings

and in a plain roller bearing at the front. This arrangement . allows for expansion of the worm shaft. There is a doubleacting synthetic oil seal where the shaft protrudes and the casing holds three gallons of oil. Tapered roller bearings

support the worm wheel, whilst the differential wheels and bevel pinions are notably large. Hardened washers look after the thrust loadings of these gear. ' Adjustable bearings, also of the tapered-roller type, arc incorporated in the hubs, and efficient provision is made' to retain the lubricant here. Furthermore, the axle case is equipped withnon-return-groove bushes to check' the flow of oil from the centre. _ Several attractive features characterize the brake system. Servo operation is effected by the Dewandre vacuum system, the power being transmitted by Lockheed *hydraulic apparatus. An exhauster, . driven as an engine auxiliary, creates the depression, and the' system' includes two vacuum tanks with a diverter valve between them, so that the auxiliary tank is fully exhausted quickly.

At both front and rear, the hydraulic

Operating cylinder's, which are of the telescopic type, are externally mounted, whilst R.P. automatic adjusters are incorporated in the rear-brake mechanism. It is of note that the rear-brake camshafts work in the needle-roller bearings. Direct application of only the reat brakes is effected by the

• hand lever.

Here are the dimensions of the brake shoes:—Front, 17 ins. diameter by 31 ins, wide; rear, 161 ins. by 61 ins.; total braking area, 499 sq. ins.; ratio of area to laden weight (11 tons), 1 sq. in. to 49 lb.

Nickel-steel channel, having a maximum section of 1014 ins. by 2-7,ins, by i in., forms the frame side members. These are braced by four channel cross-members and two 4-in. tubes.

Suspension is by semi-elliptic silico-manganese-steel . springs with bronze bushes and 11-in. chromium-plated shackle pins. Luvax hydraulic shock absorbers are standardized at both ends. Normal tyre equipment is 10.5-20 on the front wheels and 9-20 twins on the rear.

With a wheelbase of 16 ft. 3 ins., the chassis has an overall length of 26 ft. and the distances from the driver's dash to the end of the frame and to the rear-axle centre are, respectively, 21 ft. 6 ins. and 14 ft. 0-176 in. The frame is 3 ft. 101 ins. wide. Fully equipped, the chassis scales 4 tons 16 cwt.

Among other miscellaneous, but important, points may. be mentioned the two-point spring mounting at the front of the engine and the "one-pdint" semi-circular oilwoof rear engine mounting; the anti-distortion radiator fixing; the 28-gallon leadcoated fuel tank; the Marles doubleroller steering gear; the 24-volt 38-amp. compensated-voltage-control dynamo, with Exide 185-amp.-hr. batteries made up of four 6-volt units; and the Tecalemit grouped and boxed lubricators.

A brief description of the radiator fixing is merited. At the base the two support brackets rest on Silentbloc bushes, through which pass the vertical holdng-down _bolts. At the top there are horizontal tie-rods, the forward ends of which pass through similar rubber bushes secured by housings to the header tank. Their rear ends have jaws engaging dashboard eye-bolts.


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