Continentaltype Bristol P.S.V. Chassis
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RESEMBLING certain current Continental types more than contemporary British designs, a highly inspired 36-ft. x 8-ft. 2.5-in, singledecker passenger chassis has been developed by Bristol Commercial Vehicles, Ltd.. Brislington, Bristol, 4, for use with 54/56-seat bus or 48-seat coach bodies to be built by Eastern Coach Works, Ltd., Lowestoft. Known as the RE, this new Bristol chassis has a horizontal Gardner engine mounted below the frame and behind the rear axle, air suspension at both axles and an airhydraulic dual-circuit braking system.
There are two versions of the new model, these differing principally only in respect of frame height: the RELL lowframe chassis has been designed for stage-carriage bodywork. and the chassis"rame height forward of the gearbox is 3 in. lower than that of the RELH coach3ody model. The RELL has a chassis 'might of 25 in. ahead of the front axle ind 28.75 in. immediately behind the 'rent axle. whereas these respective limensions in the case of the RELH are 18 in. and.31.75 in., the difference being iecounted for by slight cranking of the nain frame members immediately ahead -4 the rear-suspension pivot points. The deter frame line of the coach chassis iermits an underfloor full-width luggage ocker between the axles. The frame teight in the immediate vicinity of the ear axle is the same-36,25 in.—in both uses.
19-ft. Wheelbase
The RE design has a wheelbase of 9 ft. and front and rear overhangs of ft. 7.5 in. and 10 ft. 4.5 in. respectively. 'he pressed channel-section side members re 10 in. x 2.75 in. x 0.25 in., tapering 3 6.25-in, deep at the front. There are ix channel-section and three tubular ross-members bolted in place, and the )w-frame version incorporates' bodyIppon outriggers.
The standard power unit is the Gardner HLX. rated to give either 150 b.h.p. or 20 b.h.p. at 1,700 r.p.m. Alternatively, se Gardner 6111.W 112-b.h.p. unit can e installed, with the further option of orizontal versions of the Bristol BVW iesel set to match any of the Gardner itings. The engine faces to the rear. nd carries an air-assisted 16.25-in.iarrieter clutch, from which a shaft runs )rward, above the Lodekka-type rOpped-centre rear axle,. into the fivexed synchromesh gearbox. This box, hich incorporates an air-assisted gearaange, has forward ratios of 4.07, 2.3, 45, 1 and 0.70 to 1. with an optional attom-gear ratio of 4.7 to 1: reverse is 1 to I.
From the ouput of the gearbox a short shaft with Hardy Spicer 1600-series joints (as opposed to the 1500series joints of the engine' gearbox shaft) takes the drive into the front of the axle, the alternative ratios of which are 4.36, 4.77 or 5.6 to 1. The front axle is a Bristol assembly of conventional design, and Burman recirculating-ball steering is employed.
Following satisfactory service life with air suspension at the rear axles of Lodekka doubledeckers, on which this suspension is standard, and on a number of MW
single-deckers, Bristol have decided to adopt full air suspension as standard for their RE Models. The front suspension is by a single rolling-lobe diaphragmtype air spring at each side of the frame, with axle location by trailing radius arms and a lower tie -rod. At the rear there are two rolling-lobe air springs at each side of the frame, one behind and one in front of. the axle, and a pair of long trailing radius -arms. Panhard rods provide lateral location at both axles, nodelay levelling valves are used, and heavy-duty dampers are incorporated. Bristol cam brakes-16.5 in. x 4 in. at the front and 16.5 in. x 7.5 in. at the rear ---give a total lining area of 575 sq. in. These are operated by an air-hydraulic .system which consists of an air servo and a 2-in.-bore hydraulic master cylinder to actuate the frame-mounted rear-brake slave cylinders, and an air-hydraulic "power pack" controlled by the rearbrake servo and actuating stub-axlemounted slave cylinders, the two circuits being .independent of each other.
9.00-20 Tyres An exhaust brake is offered as an optional extra, service experience with this having confirmed improved lining life and rednced adjustment frequency. The electrical system is 24v., the four batteries being carried on the left side of the chassis, ahead of the rear axle. D.C. or A.C. generators can be fitted. The fuel tank, has a capacity of 34 gal., and is carried ahead of the right-hand rear wheel.
The weight distribution of the RE design is such that 9.00-20 (12-ply) tyres can belsed all round. The two different
types of body have basically the same structure, high-duty aluminium alloy being used throughout, with the exception of the timber flooring. The bus body has power-operated double doors ahead of the front wheel and is available with either 54 or 56 seats. Fluorescent lighting is provided, and body heating is given by the forward-mounted radiator in conjunction with an exhaust heat-exchanger.
48 Standard Seats The coach body, which can seat 48 when standard coach seats are employed, but a reduced number if reclining seats are fitted, has a single inward-opening door and a total of 130 cu. ft. of luggage accommodation, most of which is under the floor. Both vehicles have deep, fullwidth wrap-round windscreens and paired headlamps, features which give improved driving safety, whilst it is obvious that the predominance of powered controls will make the RE a light vehicle to handle.
Various other changes to the Bristol range have been announced also, the most important of these being that the maximum-capacity tractive unit is now being fitted with a Gardner 6LX 150b.h.p. diesel engine and David Brown 657 overdrive-top constant-mesh gearbox, as an alternative to which a Bristol six-speed box will be offered in due course, The flat-floor Lodekka chassis remains basically unchanged, except for the adoption of a different radiator grille, whilst minor changes have been made to the Bristol BVW six-cylinder diesel engine, mainly by way of cleaning up the design.