Thornycroft.

22nd November 1927, Page 168

22nd November 1927

Page 168

Page 168, 22nd November 1927 — Thornycroft.

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Thp ROMINENT amongst. the fine ex hibits of thia Well-known company is the new type A6 passenger chassis, designed for carrying 20-seater bodies. It has a six-cylindered power nnit of 3i-in. bore and 5f-id. 'stroke, developing 60 b.h.p.ot--1,500 T.p.m. and up -toa maximum of 70 ti.h.p. A striking point in the deaign is .that. the -six-cylinder barrels are pressed into a single casting forming the water jacket and carryingside-bysside valves. This keeps the .eylinder block remarkably free from .distortion and enables worn cylinders to be replaced as required. Seven bearings are employed for the crankshaft ; they are of die=caSt white metal.

To avoid torsional Oscillation causing noise in the timing gears, the single camshaft is driven from the rear end of the crankshaft. The engine and gearbox form a unit, carried at three points in the chassis frame. The suspension of the front takes the form of a bearing -with cap, both lined with rubber.

'Careful attention has been given to adequate lubrication and the oil is thoroughly filtered, and supplied to all important points, the timing gears, for instance; being supplied by the overflow from the relief valve. A thermostat regulates the cooling of the engine. Four-forward speeds are given by the gearbox and both the brake lever an change-speed lever are carried at the centre. Power is conveyed to the gearbox through a single-plate clutch with

light-driven member.

Conforming with modern practice, the propeller shaft is in two sections, the centre bearing. being mounted in a Hardy flexible disc carried on a crossmember, thus preventing metal contact. Overhead worm gearing is employed for the final drive. -Cast-steel hubs running ontaper roller-bearings are used for the disc wheels and the chassis is intended, only for employment on pneumatic tyres. Side-by-side internalexpanding bands, in place of double

shoes, are used for the brakes. Frontwheel brakes are, also employed.

To assist the coachbuilder in obtaiuing a low floor level, permanent outriggers are bolted right across nun underneath the frame. The wheelbase is ample for a vehicle of this capacity, being 15 ft.

On a similar chassis to this is shown 20-seater Lightning coach. In this vehicle doors are provided at each Iside of the driver's seat; sufficient space. being .allowed to permit passengers to pass to and from the central ganomy.

The type J.J. 5-tanner :is..alsd on view. This, however; has a 'fourcylinclered engine and is realli a development of the famous type J., which, has ,provest. so suecessful in the tast. The specification now includes taper roller-hearings for the . wheel .hubs and it is mounted on detachable disc wheels with 40-in. by 8-in, pneumatic tyres. Here, again, unit construction is I employed for the engine, clutch and gearbox, :thus ensuring perfect alignment.

There is a 32-seater service bus with front and rear entrances, mounted on . the B.C. Forward chassis, the weight of which is 3 tons 4 cwt.

No Thornycroft .exhibit would be fully representative without an example of the famous .six-wheeler, and that shown is the type A3 Subsidy. This is

2-3-tonner, which has already beeu described in The -Commfroial Motor.

The type A2 Subsidy also on_ view iEr a 24oir freight Machine, With unit construction of' engine.and gearbox, two Hardy joints in the singlepropeller shaft and overhead worm-drive.

.there is the 30-cwt. Al. Subtidy chassis', which, in this instance, is shown. equipped. with a 30-est. box-van. . body for the Great Western Railway. „

Visitors slieuld also see the large ,Thornycroft rigid six-wheeler, fitted with a remarkable three-compartment petrol tank for bulk deliveries of fuel, and shown by the tank Makers, Thompseri Bros. (Bilston); Ltd.

Thornycroft.

Page 168

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