THE MEDIUM-S1ZED PASSENGER CHASSIS.
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Details of One of the Range of Berliet Passenger Models, which is Built for Carrying 20-seater Bodies.
TE continual expansion throughout the country of Passenger transport services has conclusively proved the benefit of the motorbus to the general public, and it may be stated with perfect surety that many provincial services can be adequately and efficiently served by vehicles haring a seating capacity for 20 passengers. Saloon omnibuses of this capacity are not only economical to run from the point of view of petrol, oil and maintenance expenses, but a oneman type of body can be fitted with consequent saving in personnel.
One of the successful chassis in use as a medium-sized bus chassis is the Berliet, marketed by Automobiles M. Berliet, Richmond Bridge Works, Twickenham, a large number of which is in operation in this country and the Colonies, and which has been on the British market for some years. This chassis has undergone several detail modifications and these have been thoroughly tested during the past season.
The chassis is equipped with a four-cylindered engine, having a bore of 90 mm. and a stroke of 130 mm., the cylinders being cast en bloc and in one with the top half of the crankcase, a detachable cylinder head being fitted to facilitate decarbonization. The Crankshaft is carried in the top half of the crankcase, three main bearings being employed. The crank webs are drilled for pressure lubrication, the two. centre big-end journals being served from the centre main bearing. The small end of the connecting rod is split and fitted with a setscrew, which locks the gudgeon pin in position. The pistons are of cast-iron, three rings being provided, all above the gudgeon pin, which latter takes its bearing in bosses in the pistons. The inlet and exhaust valves are located Oli the left-hand side of the engine. The tappet heads are most accessible.
Thecentrifugal water pump and magneto are located on the left-hand side of the engine, the water pump being sittnted at the front and the magneto being driven by an extension of the water-pump spindle, through the intermediary of a flexible disc coupling. The water pump is driven by a helical-toothed gearwheel which meshes with the camshaft gearwheel. The spindle of the pump and magneto driving wheel is also brought out through the front of the timing case and carries the driving pulley for the fan, a flat belt being employed. The fan itself is mounted on the cylinder head and a positive means of adjustment for the tension of the belt is provided.
Lubrication is on the pressure system, a gearwheel pump, driven by skew gearing from the camshaft, being located in the lower half of the aluminium crankcase. This pump delivers oil to the three camshaft bearings, whence it flows to the main bearings AN then by ducts in the crank webs to the big-end bearings. All oil drains back to the sump, which is entirely covered by a fine gauze screen. The pressure release is embodied in the oil pump itself, while a pressure gauge on the dash indicatFs that the system is working satisfactorily.
Carburation is attended to by a Zenith triple-diffuser, in conjunction with a vacuum feed from the petrol tank it the rear of the frame. • Mounted on the right-hand side of the engine; at the rear of the timing case, is the single-unit sta'iter-dynamo, which is driven by a silent chain from the front end of the crankshaft. A combined cut-out and starter switch is used.
The engine is three-point suspended in a frame, the front of-the timing case being elongated and resting in a trunnion bearing in the centre of the front chassis cross-member, whilst the flywheel is surroulded by a pressed-steel housing, which is bolted to the rear of the crankcase and embodies two arms which, in their turn, are bolted to the side members
of the chassis frame. • A multiple dry-plate clutch conveys the drive from the engine to the gearbox. Bolted to the rear of the bell housing surrounding the clutch and flywheel is the fourspeed-and-reverse gearbox. Mounted on the top of the gearbox casing is the change-speed lever and the hand-brake lever, which are thus positioned at the driver's left hand. The foot brake is of the internal-expanding type, the shoes being faced with Ferodo. It will be seen that the engine, clutch and gearbox form a unit, which is suspended from the chassis frame at three points.
The foot-brake drum also serves as an anchoragefor the flexible disc universal joint at the forward end of the open tubular propeller shaft. At the rear end this shaft is splined and mounted on it is the spider of the rear universal joint.
The rear axle is of the overhead worm type and is semi-floating. It is attached to the chassis frame by long semi-elliptic springs, which take all driving and torsion strains.
The hand-brake drums are integral with the rear hubs and are of large diameter, whilst the hand-brake shoes are faced with Ferodo, in the same way as the foot brake. The gear ratios from engine to road wheels are as follow :—First speed, 23.25 to 1; second speed, 15.75 to 1; third speed, 10 to 1; fourth speed (direct drive), 6.25 to 1. The chassis is equipped with electric bead, side and tail lights, detachable disc wheels, single wheels and tyres on the front axle and twin wheels and tyres on the rear axle; the standard tyre equipment being pneumatic tyres of 835 mm. by 135 mm. section all round.
The dimensions of the chassis are as follow :—Overall length, 16 ft. 8 ins.; overall width, 6 ft. 2 ins.; dash to end of frame, 12 ft. 3 ins.; width of frame at rear, 3 ft. 2 ins.; wheelbase, 12 ft.; track, front, 5 ft. 3i ins.; track, rear, 5 ft. 1 in. The weight of the bare chassis is 27 cwt.
There is a demand for a chassis having a longer wheelbase so as to enable more luxurious bodies to be mounted. For this reason a chassis is available with a wheelbase of 13 ft.
The present price of these chassis is £350 delivered in London.