Two Important NEW COMMER CHASSIS DESIGNS

5th November 1929, Page 154

5th November 1929

Page 154

Page 155

Page 154, 5th November 1929 — Two Important NEW COMMER CHASSIS DESIGNS

Noticed an error?
If you've noticed an error in this article please click here to report it so we can fix it.

The Latest Additions to the Range include a Chassis to Carry 32-50-seater Bodies, and a Goods-carrying Machine of 6-7-tons capacity

IN our issue dated October 29th we gave a full description of the new Coramer, which is to be known as the Invader, designed for 20-seater bodies or two tons of goods; in these pages we

describe two further types. One is designated the Avenger—a fast passenger-carrying chassis suitable for bodies of 32 to 50-seats capacity. The other machine is a normal-control type for 6-7-ton loads.

The most striking point is that the front axle of the latter is behind the engine. This has been done with the intention of imposing rather more weight than is usual on the front axle to relieve the driving axle which, in certain D56 eases,when a full load of seven tons is carried, may be over the legal limit of eight tons. In addition, twin tyres are usually the maximum that can be used under the width limit of 7 ft. 6 ins, This equipment has a carrying capacity of eight tons.. By relieving the rear axle of some of its load, the 8-in. tyres are brought well within their weight limit. The general specification of the Avenger passenger chassis is as follows :—a six-cylindered engine, giving over 100 b.h.p., drives through a singleplate clutch to a four-speed gearbox mounted in unit -with the engine, and the power goes through a two-piece propeller shaft to an underslung worm axle, in which the half-shafts are fully floating.

Going into further detail, we find that the frame is of 9-in, maximum depth, is down-swept behind the dash, and then runs horizontal until the point is reached where it is up-swept to clear the rear axle. In plan, the frame is parallel until a point behind the gearbox, where the members sweep outward and then run parallel to the rear extremities. There is one front crossmember bolted to the engine to act as its forward support, whilst the rear of the power unit is carried by a bridge member connected to the clutch pit. in addition, there are five tubular crossmembers in the frame. The gilled-tube radiator is carried on the front crossmember.

Some Salient Features of the Six-cylindered Engine.

The six-cylindered engine has a monobloc cylinder casting bolted to an aluminium crankcase; the bore and stroke are 105 mm. and 140 mm. respectively. The cylinder head is made in two detachable portions, whilst the underside of the crankcase is closed by an aluminium sump with a ribbed oilwell at the rear. Seven bearings carry the crankshaft, which drives the camshaft through a roller-chain distribution gear with an automatic tensioning device. The side-by-side valves are on the near side of the engine.

The distribution drive serves the magneto—which is carried on an Inclined platform—the dynamo and water pump in tandem and the positively

driven fan. Pressure lubrication is used throughout. Oil filters are provided on both the suction and pressure sides of the pump, the latter being outside the crankcase, and it is cleaned every time the dutch pedal is depressed. A governor can be fitted, but this is not standard practice. The inlet and exhaust manifolds make contact at their centre to give a hot-spot for the induction. A thermostat also can be installed.

Fuel is supplied to the carburetter from the 40-gallon tank 'carried on the frame outriggers ; the quantity in the tank is recorded by a Simms gauge.

Control for the four-speed gearbox is by a right-hand lever working in a gate, which conveys the effort to the selectors through a single rod running inside the frame-member. No binding action can occur in the change-speed mechanism. Two fabric universal joints are fitted to the primary propeller shaft; the intermediate bearing is carried by a massive tubular cross-member. Aft of this a tubular shaft with Hardy-Spicer joints is connected to the worm shaft of the rear axle.

Marles-type steering is used; this can be fitted on the near side if required for overseas service.

Four-wheel brakes are operated through a Dewandre servo device. The other set in the rear wheels is actuated by hand lever.

Springing Equipment and Some Leading Dimensions.

Semi-elliptic springs of the dividedmaster-leaf type are used, the front ones being 3 ins, wide and the rear ones 4 ins., whilst the respective lengths are 4 ft. 3 ins. and 5 ft. 6 ins. The tyres are 36-in. by 7-in. Dunlops, and the wheels run on roller bearings. The equipment includes a 12-volt dynamo and starter, five lamps, horn, mechanical tyre pump and speedometer, together

with a spire wheel and tyre. At 2,000 r.p.m. on top gear the road speed is 37.56 m.p.h., or 34.54 m.p.h., according to the final gear ratio selected.

The leading dimensions of the Avenger are :—Wheelbase, 16 ft. 4 ins. ; overall length, 26 ft. ' turning circle, 58 ft.; overall width, 7ft. 5 ins. ; body space, 21 ft. 31 ins.

The 6-7-ton Chassis for Goods Transport.

Turning now to the 6-7-ton goods chassis, this has a platform space of 15 ft. on the model baring a wheelbase of 14 ft., whilst 16 ft. 6 ins, is the length available on the 15-ft. wheelbase chassis. A. 12-ft. wheelbase model is available for tipping bodies.

So far as the engine and gearbox unit, and transmission line, are concerned, the specification follows that of the chassis already described. The controls, of course, are located behind the engine, and a governor is -fitted. Two power take-offs are provided on the gearbox, one for a mechanical tyre pump and the other for a tipping gear.

An overhead-worm axle is employed. This is of the fully floating variety, and is reinforced internally with nickelsteel tubes. Marks steering, which can be mounted on the right or left of the machine, is standard. Two sets of brakes are fitted to the rear wheels, the drums being 20 ins, in diameter and each shoe 31 ins. wide. Dewandre vacuum-servo actuation is employed for the service brake. The rear-axle casing is of the built-up variety, the three portions being bolted together.

The pressed-steel frame has a maximum section of 10 ins. by 2i ins. by 5-16 in. Dunlop 40-in. by 8-in. tyres can be fitted ; solid tyres are optional. The equipment is similar to that of the passenger model. Two standard axle ratios are offered-7.2-3 to 1 or 9.14 to 1. These give respectively road speeds of 31.1 m.p.h. and 25.5 m.p.h. at 2,000 r.p.m. of the crankshaft.