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A CHASSIS FOR SINGLE OR DOUBLE-DECK BUS SERVICE.

18th September 1923
Page 19
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Page 19, 18th September 1923 — A CHASSIS FOR SINGLE OR DOUBLE-DECK BUS SERVICE.
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An American Design which Incorporates a Six-cylinder Engine and ' Other Unusual Features.

OUR READERS will have noticed that of recent months we have paid considerable attention to the growth and development of the travelby-road movement in America, and have published at frequent intervals descriptive articles and illustrations of the latest types of motorbuses and motor coaches which have been designed and constructed in the works of some of the most prominent manufacturers in the United States. There is a definite reason for this procedure. We feel that, although conditions surrounding the operation of passenger vehicles in this country and In America may be somewhat different, by keeping in close touch with this progress we can impart

useful knowledge to our readers and provide them with a ready opportunity of making comparisons in relation to chassis design and bodywork practice.

It must be remembered that this country virtually set the fashion to the world in the matter of the establishment of a comprehensive network of regular passenger-carrying services. Such strides have been made in the States during the past few years, however, that our cousins across the water do not now lag far behind their European rivals. Although many types of passenger vehicles are in use in America which are reflective of British practice, there are certain classes of buses and coaches which have no counterpart iat Great Britain. In fact, it might be said that American manufacturers, having pro fited from the experience of their British confreres, have even surpassed them in some respects. This remark does not, perhaps, apply so much to chassis design as to bodywork, although. in considering this statement, one must not overlook, the stringent regulations with which hackney carriages in this country have to comply, arid which appear to be more restrictive than those in force in the States.

This contention can be supported by taking the case of the covered-in double. deck bus. For many years past the London Genes-al Omnibus Co., Ltd., have made strong endeavours to convince the Scotland Yard authorities of the safety of this type of vehicle for regular service, and although their untiring efforts appear to be likely to meet with ultimate -success, such buses have long seen service on the streets of some of the largest American cities.

As a matter of fact, a new chassis which has just made its appearance in the States is suitable for carrying a covered-in double-deck body. This chassis which is known as the Model P Philadelphia, is also suitable for use as a single-deck vehicle, and it is primarily intended for urban bus transportation.

The chassis incorporates several unusual features in its design, chief amongst which is the utilization of a six-cylinder engine, which was designed by Mr. E. 0. Spillman. The power unit, is of the valve-in-head type and it has a bore of 4 ins. and a stroke of 6 ins., the power developed at 2,400 r.p.m. being 90 b.h.p. The engine has a seven-bearing crankshaft arid, in order to facilitate valve grinding and cleaning of the piston heads, a removable i cylinder head s used.

Another feature of the engine is the inlet manifold, which incorporates a hat. spot into which all the condensed vapours are drained and revaporized, so that a dry mixture is passed to the cylinders under practically all working conditions. A high-pressure force-feed system of lubrication is adopted, the pressure being controlled by the throttle opening, so that the oil is supplied in accordance with the load on, the vehicle rather than

the speed of the engine. The cooling -water is circulated by a centrifugal

pump, and the dissipation of heat is aided by a four-bladed fan and a tubular rtidiater with an aluminium shell.

The standard practice of the makers is to employ a battery for ignition pur poses, although a high-tension magneto can be fitted if necessary. The electrical equipment includes a starting motor with Bendix drive.

The engine power is conveyed to a multiple dry-disc clutch of the Brown Lip e type, and thence to a four-speedand-reverse gearbox, the reduction on low gear being 4 to 1. The rear axle is of the cranked type and the final drive is by internal gears in the rear wheels, on which both foot arid hand brakes operate, the total effective braking area being 730 sq. ins. The maximum depth of the channels used for the frame is tl ins., the dis tance from the top of the frame to the ground being only 1 ft. 6 ins.; this low centre of gravity is secured by up sweeping the frame over the rear axle. The actual loading height of the vehicle is 1 ft. 7L ins.

Much attention has been deyoted to the question of springing, and, apart from the ordinary semi-elliptic suspen sion, the Iliflex auxiliary springing device is used both at the front and the rear. This suspension comprises helical springs mounted on a hinged device which operates between the ordinary shackles and the frame.

The system of control of the vehicle differs from usual British practice, spark and throttle levers being car ried on a quadrant on the steering column. The hand brake and gear levers are mounted in an independent control set within easy reach of the driver's right hand. It is interesting to note that the compartment in -which the driver is enclosed is entirely isolated from the passenger-carrying portion of the body; moreover, it is fitted with curtains to avoid refraction frons the interior lights.

Several types of bodies have been designed for fitting to the Philadelphia chassis, that shown in our illustrations (for the reproduction of which, and also the details, we are indebted to our con

temporary BUR Transportation) being

a 65-seater double-decker of the semi enclosed type. This is a • typical American bus body, and the manner in which the upper deck is partially covered affords ample protection to passengers. The covering extends the full length of the body and protects the

seats, a central aisle being .left for the convenience of the conductor when col

lecting fares and for the benefit of passengers when getting in and out of the seats. This type of body was, originally used on the double-deck buses in service in Detroit, where it has apparently given every satisfaction.

The overall height of the bus is 12 ft., which gives a 6-ft. clearance under the roof of the lower deck and 4-ft. headroom on, the upper deck below the covering. .ITo give the driver perfect control over the vehicle and render it unnecessary for

the conductor to mount, the stairs to warn passengers an the upper deck of overhead obstructions, a' system of clearance signals has -been arranged. .

B38 When a bridge, or other obstruction, is about to be encountered the driver switches on a green bull'saeYeat, the rear, the light from which .is directed along the centre aisle to a mirror at the front, and thence reflected through other mirrors so that it can be seen by the driver. Obviously, if a passenger is standing in the aisle this light does not appear and the driver is thus warned that it is inadvisable for hint to proceed. At the same time, 'the driver switches on an electric sign calling attention to the .danger, and an audible signal warns any passenger who may be standing to 'be seated and out of danger.

The bus body is of more or less conventional construction. The superstructure is of ash reinforced at vulnerable points with steel plates. The panels anal roof are of a material known as Baskelite, which is largely used in the States.

As the yehiclwis-iintended fonall-theyear-round operation, a system of heating for the interior has been adopted, the engine exhaust gases being used for this purpose.

The length of the chassis is 24 ft. and the wheelbase 12 it.

Tags

Organisations: Scotland Yard
Locations: Philadelphia, Detroit

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