New Guy Saves Over 2 Tons: Five-speed Gearbox Standard
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WHEN The Commercial Motor road W tested the Guy Arab passenger chassis of 16-ft. 4-in, wheelbase with a 44-seat body (August 8, 1952), the recorded unladen weight was 8 tons. A new Guy Arab lightweight passenger chassis has been. fitted with a Saunders "Roe Saro light-alloy body having similar box dimensions of 30 ft. by 8 ft., and the unladen weight is 5 tons 17 cwt. Of the total saving of 2 tons 3 cwt„ about 14 cwt. can be attributed to the chassis and the remainder to the lightweight body construction.
These comparisons are based on the lightweight chassis powered by a Gardner 6LW engine, which was the unit installed in the test vehicle.
Detail modifications to the frame are included in the interesting features of the chassis. The rear overhang has been shortened and a small reduction made in the depth of the main members. Lightening holes have been more liberally used to reduce the weight of the cross-members, and other small modifications have been made to the frame layout, including a reduction of frame depth in the engine bay from 7 in. to 6i in.
An interesting feature of the body is that the structure provides support for the floor at the rear and no extension of the chassis is required at the back of the rear shackle brackets.
The front tyres remain unchanged, 10.00-in. by 20-in, covers being fitted. The lower unladen weight has, however, enabled 9.00-in. by 20-in. tyres to be fitted to the twin rear wheels, in place of the larger covers. The fronttrack centres have been increased from 6 ft. 944 in. to 6 ft. 10* in.
Two major changes in equipment are the fitting of a five-speed constant-mesh gearbox and a friction clutch as standard equipment (a Wilson four-speed or five-speed epicyclic gearbox and fluid coupling are available as alternatives), and the replacement of the upderslungworm final drive by a spiral bevel.
An overdrive top gear is employed giving a step-up ratio of 0.735 to 1. The remaining ratios are: first, 4.51 to 1; second, 2.83 to 1; third, 1.74 to 1; fourth, direct; reverse, 4.58 to 1. Both the mainshaft and layshaft have centre bearings supported by robust webs to reduce deflection and eliminate noisy running.
Whilst the original type of threepoint engine mounting is retained, the contra-flow radiator has been moved from in front of the axle to a position at the rear of the axle, the air supply being drawn through a cowl. A coldair intake for the engine at the front of the radiator supplies a heavy-duty oil-bath air cleaner on the off side of the main frame, the connections being corrugated rubber hoses. The exhaust pipe has been shortened and the tail pipe is now led out ahead of the rear axle on the off side.
Other mounting modifications include transferring the triple-servo units from the front of the engine to a rear position adjacent to the clutch housing on the off side, to facilitate the change in radiator mounting. The vacuum reservoir has been transferred from outside the main members on the near side to a transverse position at the rear of the back axle.
Following Saunders Roe practice, the body is built of eight main units which comprise the sides, roof, front end, underframe and floor, rear end and entrance unit. The side framework is formed of H-section pillars attached at their upper ends to a continuouschannel cant-rail.
The roof sticks are of Z-section with pressed corner diaphragms, attached to full-length channel-section side
members by angle cleats. The construction of the front-end unit is based on contoured angle-section corner pillars with vertical diaphragms and folded-sheet waist members. The entrance unit is built into the body as a complete assembly to ensure the correct alignment of the doors.