The First Four-Cylinder Renault Taxi Chassis.
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A Description of a New Model for which There have been Many Demanis.
An entirely new model of Renault taxi chassis has made its appearance in this country. Robert Bell, Ltd., the automobile engineers and agents for Unics, of 45, Horse
ferry Road, We has secured the whole of the first batch of this interesting new industrial model for sale. This company also has obtained options on further batches of the same type.
The " Renault two-cylinder" has achieved for itself a remarkable reputation in the matter of motorcab reliability and low maintenance charges. If it were not for the limitation of the number of cylinders on that Renault model, drivers and owners would testify without exception that there are few taxicabs which could beat the Renault on all points.
Frequently in the past have we heard both drivers and owners say that. if the "two-cylinder Renault" had a four-cylinder engine (sir) they would want. nothing better to run
for taxicab service generally. This generally-expressed wish has now been gratified. Mr. Robert Bell notified THE COMMERCIAL MOTOR immediately he was in a position to say that the first of the new models had been shipped to his order in this country, and we are happy to be able to give to our readers the first-published description and illustrations of it, herewith.
The new model differs from its predecessor, as we have said, principally in the matter of engine, but the whole chassis has constructional features which distinguish it in a marked degree from the smaller design. The bevel-gear live axle is retained ; the gearbox has three speeds and a reverse, whilst, of course, the wheelbase, turning lock and underneath clearance comply with the respective requirements of Scotland Yard.
The engine has its four cylinders east in one piece, and each of these has a bore of 70 min., whilst the
piston stroke is 110 min. The total capacity of the cylinders is 103.2 cubic inches, One or our illustrations will convey quite clearly to our readers the compact. and workmanlike design of that part of the chassis which is " under the bonnet." All the valves are on one side of the cylinder casting, and are located in pairs under separate valve covers. A Bosch high-tension magneto is situated well out in the front of the engine in a most accessible position ; it is driven by means of a worm gear on a front extension of the camshaft, and through a friction-adjusted coupling.
The lubrication system on the engine is, in conformity with other Renault practice, a carefullythought-out job. Oil is poured through an aperture in the front two-to-one gearcase, to which access is given by means of an ingenious plug that is easily detached. The sump is situated at the bottom of the lower half of the crank-ease, and the level of the oil therein is shown by means of a float-operated indicator at the side of the engine. Oil is pumped from this sump through filters into the main bearings by way of the hollow journals of the crank-shaft, and from there it travels by way of separate oil rings to the crankpins. All the other internal moving parts of the engine are ensured a sufficiency of lubricant by means of carefully-arranged channels and pockets inside the case.
The carburetter is of the latest form, and is that which has been adopted on recent Renault Pleasure.-car models, It consists of a throttle with serrated edges, which is vertically disposed over the jet. lin accordance with Renault. practice, provision is made for the easy
control of the ordinary air supply, as well as for a separate induction of hot air, which is taken from the jacketed exhaust branch. Thermo-syphon water cooling is, of course, a feature of this design, and the bonnet is of the well-known Renault pattern ; its increased overall dimensions will, however, readily distinguish this model from its " two-cylinder" sister.
The flywheel has externally-disposed blades, which draw the air through the multi-tubular radiator, which, in this particular model, is placed rather higher than usual.
The clutch, of the internal leather-faced cone type, with an enclosed spring, is operated by a neat arrangement of levers from one of the pedals, as usual. The fulcrum for this is in the form of a steel stud, which is screwed into a suitable boss on the front end of the gearbox.
The gearbox itself is of the " pot " type. Access to its interior is by way of a large circular cover, held down by one nut. All the shafts have to be erected and dismounted endwise through the housings of their bearings. As will be seen in the illustration of this part of the chassis, the foot brake is an internal-expanding one, on a drum that is situated immediately behind the gearbox. The shaft for the operation of this brake is carried, for convenience, in bearings through the centre of the gearbox over the gears. The sliding gears provide, as we have already intimated, for three speeds forward and a reverse, and these are actuated by a crank pin which engages with a vertical slide that is connected with the sliding-gear members, The rotation of this pin, as a crank, pushes the sliding members of the gears backwards and forwards on their own castellated shaft. The gear-operating crank pin is carried in a disc, which is rotated by a small gear pinion, which in turn engages with a gear sector, The sector is carried on the main operating shaft, on the other end of which is the change speed hand lever. The definite location of each speed is effected by a small plunger, which engages with suitable indentations in the periphery of the crank disc to which we have already referred.
The drive is taken to the beveldriven back axle by means of a short length of propeller shaft, and through the usual universal joints at both ends. The front joint is enclosed in an oil case, which is carried by one of the cross members of the frame. The back axle itself is of normal type, but we would draw the attention of our readers to the substantial nature of the tubular torque rod and to the manner of its fixing to the bevel-gear casing. The back axle supports the frame by means of three-quarter elliptic laminated springs, the lower portions of which are underhung on the axle. This last attach
ment is by means of spring brackets, which enclose split gunmetal bearings in such a way that they allow the axle itself freedom to rotate therein. The back brakes are again of the internal-expanding type, and call for no specific mention.
The steering gear on this model is, of course, specially designed to enable the chassis to turn within the usual 25 ft. circle required by the London licensing authorities. The front steering rod has forked ends carried in front of the axle. The fore and aft connecting rod has ball couplings which are not pen dant.. The steering gear itself is of the simple worm-and-segment type. The limit of lock is settled by rear extensions to the shanks of the steering arms. All the road wheels are carried on ball bearings, and we are informed that 810 mm by 90 mm. pneumatics will be fitted as standard.
The control appears to be of the simplest type, consisting, as we have already indicated, of a single throttle, which is operated by an auxiliary pedal. The limit of travel of this control can be set by means of a small lever, which is the sole fitting that is carried on the dashboard.
Robert Bell, Ltd., informs us that it is in a position to sell this machine as a chassis or a complete cab, either by ordinary or by hire purchase, in the same way that the company handles Unics.