ROVER 12hp 1907-10

Specifications of the ROVER 12hp Cab - Project of 1907/08
A tabular description of the specifications of the ROVER 12hp ⇒ can be found here.
The Chassis
The Chassis has been built on the same lines as the world-renowned Rover Car which has won the Tourist Trophy in the Isle of Man in May last. This in itself is ample testimony. Its great value for Motor Cab work is the all important fact that every part is interchangeable. Thus, in the event of any portion being damaged or getting out of order, it can be replaced in a few minutes by a fresh part, and the Cab will thus never remain idle, but will constantly be an earning factor, while the broken part is sent to the workshop and repaired. The engine clutch, gears, etc., being made in different sections, can be detached „en bloc“, and others inserted whilst the defective section is being overhauled. This contrasts favourably with the system where the Cab is retained in the workshop until the broken part is repaired, and even then most indifferently, as the Manager’s one thought is to get the Cab on the road again at all costs, and consequently he unduly hurries on all repairs. This eventually tells on the life of the chassis as the more hurriedly and patchy the work is, the quicker will the patched up part be out of order again, and by endless patching up of this kind the chassis soon becomes fit for nothing but the scrap heap, whereas by proper treatment it would undoubtedly last years longer.
The Engine
The engine of the Cab chassis is made up of two separately cast cylinders of 97 mm bore. The piston has a stroke of 110 mm. Inlet and exhaust valves, mechanically operated, are set on one side of the engine. Each cylinder can be removed from its bedplate in a few minutes. The crankshaft is machined from the solid, accurately gauged, and rotates upon ball bearings, and thus evenness and ease of running are ensured for an indefinite period. Particular attention is directed to the special camshaft used in the engine, which, in addition to lifting the inlet and exhaust valves in the usual manner, is so constructed that it can be operated as an engine or compressin brake. Details of ingenious device will be found under the heading „Engine brake“. The flywheel, of more than ordinary weight, thus giving great flexibility of running, is enclosed, and revolves in a continuous bath of oil, and being placed between the crankshaft bearings within the crank chamber, is a great improvement on the overhanging external flywheel usually employed.
The Engine Brake
This is a Rover speciality of more than ordinary merit. The cam shaft, wwith its specially formed cams is arranged to slide horizontally by means a pedal on the footboard of the Cab, a spring holding it in its normal position. On the depression of the pedal, an entirely different system of valve operations is set up; the lift of both valves is at first diminished, and finally the ball which lies under the inlet valve tappet comes on a circular portion of the cam sleeve, and the inlet valve remainns closed; by this time the ball under the exhaust valve tappet is on that portion of the cam sleeve having two projections, so that the exhaust valve is opened at the top, and closed at the end of each piston stroke. Air is thus drawn into the cylinder through the exhaust valve, on every downward movement of the piston, compressed on the upward stroke of the piston, and then exhausted. The inlet valve being permanently closed, no petrol gas is admitted to the combustion chambers, consequently the intake, compression, and exhaust of air, not only tend to have a retarding effect upon the engine’s movements, but assist to cool the cylindr walls, the water circulation in the meantime continuing its work. The braking effect of this device is very pronounced - in fact, for all ordinary purposes, it can be used without utilizing the friction brakes.
The Clutch
The Rover clutch is an all-metal disc type one, containing no leather or fibre to burn or „sieze“. It is separated from the flywheel, and consists of a clutch shell and floating and fixed discs, continuously running ia a bath of oil. The depression of the clutch pedal causes the discs to separate; but, before re-engagement, the oil, which is picked up on the disc surfaces, is gradually squeezed away, so that the take-up is gradual, and not violent. The clutch has been specially designed to prevent those jars and shocks which frequently occur to cars fitted with clutches of other character. As a matter of fact, the Rover Car never „jumps“ away, but glides off from a standstill, and picks up pace rapidly.
The Gears
There are three speeds forwars and a reverse - the former give six, twelve and seventeen miles per hour. The engine can be accelerated up to 1,100 revolutions per minute, giving a top speed of twenty-one miles per hour. As with the engine and clutch, the gear bearings are of the ball type, and the pinions run in a bath of oil. An inspection plate is fitted to the gear case. The third or top speed constitutes a direct drive from the main shaft.
Transmission
This is carried out by a cardan or propeller-shaft through differential gearing on the rear live axle. The universal joint is of exceptional strength and wearing quality.
The Ignition
The ignition used is the high tension system supplied from two twenty-five ampere hour accumulators, connected by a switch. The accumulators have a sufficient capacity for a distance of between 600 and 800 miles. The contact maker is of the wipe variety, and of great reliability, while the high-speed trembler coil is of the very best make procurable.
Water Cooling
The water circulation system consists of a radiator containing top and bottom tanks and two rows of gitled tubes. The water passes from the bottom of the radiator into the pump. The pump has a two-bladed screw, which forces the water along to the water-jacket of the cyclinder, whence it passes from the cylinder head along a pipe to the top tank of the radiator. A fan driven by a belt from the fore end of the crankshaft behind the radiator assists the cooling.
Lubrication
The lubrication employed is both simple and effective, and is known as the splash system. On the side of the engine is a chamber, into which oil can be poured direct from a can by the removal of the lid, which is held in place by a winged nut. This is situated directly over the flywheel, the underside of which dips into a well where the oil is drained after running down from the cylinder walls and the connecting rod bearings. The flywheel, in revolving, picks up this oil, and throws it into the oil chamber, from which it is conducted by pipes on to the connecting rod ends. Some of the oil runs into grooves, and lubricates the connecting rod bearings. The remainder is splashed on to the cylinder walls. It then runs back to the well under flywheel, and is circulated again as explained.
Control
The control of the throttle and spark is effected by cables running through spiral tubes to the carburetter lever and contact maker respectively. These cables are attached to two milled discs or reels fitted into the periphery of the steering wheel, springs at the carburetter and contact maker governing throttle and spark, so that the tendency is to keep the throttle closed and the spark fully retarded. By winding in the reels, the throttle is opened and the spark advanced, ratchet teeth on the reels allowing any desired position of the control to be retained. The steering is effected by a worm and segment enclosed in an oil-tight casing. The speeds are changed by a side lever.
Brakes
In addition to the highly efficient engine brake already described, the Rover Cab has two friction brakes of great power. The first, worked by the right-hand pedal on the footboard, is a band brake, operating on a drum of the gear shaft. The second brake, which, under all ordinary circumstances may never be called upon - and therefore may be termed an emergency brake - is applied by a side lever which operates two internal shoes inside the drums on the back wheels.

The whole of the mechanism of the Cab is completely enclosed in a metal casing, from the engine front to the end of the gear case. The engine case is bolted securely to the clutch case, which in turn is bolted to the gear case, this forming an integral whole. The Rover Company claim, in thus enclosing the whole of the working parts of the car, complete lubrication to all parts, as the casings themselves act as oil baths. No oil can exude, and, what is of equal importance, no dust, mud, or water can get at any vital portion of the machinery. In a similar way the differential gearing and back axle are provided with an metal covering, thoroughly dust and waterproof, the differential case in itself being so contructed that lubrication for this portion of the transmission need not to be renewed more frequently than once in a thousand miles.
Suspension
The three-point suspension system adopted on the ROVER Cabs has given the greatest satisfaction to all users. The rear part of the Cab body is suspended on two laminated springs on the back axle. The springing of the front part of the Cab is, however, different from that ordinarily employed. A transverse spring is carried from one end to the other of the front-axle, on the top of which a bracket is fitted, through which passes a strong steel pin from the nose-piece of the engine casing. This bracket may therefore roll on the pin. It will thus be seen that, no matter what may be the camber or inequalities of the road surface, the alignment of the mechanical portion of the construction is never disturbed, so that no part of the transmission is subjected to undue strains.
Carburetter
The highly popular Rover automatic carburetter is used. The feed is by gravity from a petrol tank placed under the driver’s seat. The carburetter is placed in a convenient and acessible position near the engine. There are very few parts to get out of order, and the whole arrangement shows great advantages over many devices upon the market. Its construction enables the fullest possible power to be obtained from the engine.
Wheels and Tyres
Specially made artillery wheels, to suit 750 x 85 mm tyres, are used, whis one non-slipping band to one of the rear wheels. We find from experience that the lightness of the Cab, combined with the smoothness of action of the clutch, makes an appreciable difference to the wear on the tyres. This is an item which will be much appreciated after the Cab has been in use for some considerable time.
Dimensions
The wheelbase of the ROVER Cab is 8 ft 4 in / 2540 mm The track (front and rear) is 4 ft 5 in / 1346 mm Length behind dash is 7 ft 10 in / 2387 mm The Width of frame is 3 ft / 914 mm.
A l l i n f o r m a t i o n w i t h o u t g u a r a n t e e

ROVER 12 hp

Specifications of the Cab-Project

1907 - 1908