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SAUNDERS-ROE MALE GRAL BUS

20th November 1953
Page 42
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Page 42, 20th November 1953 — SAUNDERS-ROE MALE GRAL BUS
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Keywords : Axle, Tatra T813

AN integral-construction single-decker, incorporating proprietary mechanical components, has been built experimentally by Saunders-Roe (Anglesey), Ltd., for operation by Maidstone and District Motor Services, Ltd. It is a 16-ft.-wheelbase vehicle with the axles and units arranged to improve weight distribution in the underfloor-engined bus class with twin tyres at the rear, and has the Saro-type body mounted on a fabricated light-alloy underframe which has no fulllength longitudinals. In effect, the underframe is not built to take torsional or bending loads, all such loads being carried by the body.

Although having a dry weight of only 5 tons 14i cwt., the bus could be made lighter in production, because some of the ready-made mechanical units would be replaced by others to reduce weight and certain of the underframe members have initially been made more substantial than necessary to test the running components before completion of the body. Moreover, materials available at the time of assembly were used, in preference to waiting for others which would have decreased the• weight, and the operators' requirements in seating layout and the provision of a large rear luggage locker were not conducive to weight saving.

The sides, front and rear ends and roof are standard Saro lightweight •body units attached to a scientifically designed underframe having cross-beams and longitudinal members arranged in strength for the requisite load, and spaced to coincide with points of maximum stress. There are five full-width cross-bearers, formed from a 10-gauge aluminium-alloy web with angle-section beam, four being located as close as possible to the spring-attachment points.

Additional bearers support the engine, the rear bearer being an inverted top-hat-section pressing to carry the clutch and gearbox, which are attached as a unit with the engine. A tubular member is fitted at the front and the gear lever, with a cross-shaft, is attached to it.

Longitudinal reaction members of U-section,• folded from sheet are arranged between the spring shackle points, and the springs are hung directly beneath these members to avoid bending stresses on hanger brackets. In the engine and gearbox bays the longitudinals comprise 4-in.-diameter aluminium-alloytubes of -2g-in. section. The components are accessible through valence panels. All the longitudinals are spaced at maximum width to promote lateral stability, and are swept in at the front to improve the turning circle.

Ahead of the engine the second and third crossbearers are tied by a central fabricated backlgone which is gussetted to the transverse members. By fabricating the underframe in this fashion the various longitudinal members can be shaped to clear the mechanical components without .adding to the height of the platform or floor levels, or increasing the eost„as would be the ase in the conventional pressed frame. Examples are een in the shape of the members to give full bump learance over the axles and in the vicinity of the engine, there the tubular members pass over the cylinder block ,nd crankcase sump.

The mechanical components used in the prototype riclude a Gardner 51{LW five-cylindered horizontal, oil ngine developing 94 b.h.p. at 1,700 r.p.m. and 300 lb.-ft. orque, a Borg and Beck 16-in. clutch, David Brown 045 me-speed overdrive-top gearbox and Eaton two-speed xle. The engine, which has a vacuum pump for the ;Layton Dewandre triple-servo braking system, is lounted in Gardner fashion, using rubber-bushed hackles at the front and a rubber reaction member with Lydraulic damper at the rear. Its locatiOn is more wards the rear axle than is normal, so that the propeller haft linking the gearbox and axle is short.

To avoid the rieed for mechanical linkage, the clutch operated hydraulically, having the Lockheed master ylinder in direct linkage with the pedal and the slave ylinder operating directly on the throw-out lever. The lutch and gearbox are bolted as a unit with the engine, nd the linkage between the lever and box includes the ross-shaft at the front and a three-piece shaft to the ide-mounted selector gear.

An Eaton Type 16500 two-speed axle, with 12-volt electric shift gear is employed, the ratios of this unit being 4.89 and 6.80 to 1. Both the Kirkstall front axle and the rear axle are built for an 8-ft.-wide body, and the overslung springs are of maximum length for riding comfort. The spring brackets are integrated with the underframe through U-shaped members which permit the use of light-alloy material in a part which is subject to heavy shock loading.

Whilst the front anchor brackets are of conventional design, there are no shackle brackets, because the shackling is incorporated in the U-shaped members. Metalastik shackle bolts, with rubber-bonded bushes, are used throughout and the shackles and bolts are interchangeable.

Girling S-type cam-operated two-leading-shoe brakes• are employed on all wheels, the drum n diameter being 151 in., with 4f-in.-wide shoes at the front and 6-in. shoes at the rear. The Clayton Dewandre master servo is placed immediately ahead of the rear axle to be linked to a cross-shaft and rods to the cam levers.

An Isherwood contra-flow radiator is fitted because its high efficiency makes for reduced weight and size in comparison with standard units. This radiator has a four-row core and cast-aluminium detachable tanks mounted vertically, the tubes being horizontally dis posed. It is suspended behind the front axle. on Metatastik bushes, and has the shroud attached for the 18-in.-diameter six-bladed fan.

Another weight-saving measure is in the construction of the 25-gallon fuel tank, which is built of aluminiumalloy plate with Argonarc welding. This tank is suspended from the body on the rear overhang.

The Saro body is 30 ft. long and 8 ft. wide and, as supplied to Maidstone and District, has seating for 43 passengers.

There are 16 transverse twin seats, a full-width fivepassenger seat at the rear and two three-passenger longitudinal seats over the front wheel-arches to ensure a clear loading platform.

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Organisations: U-section,•
People: David Brown

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