... It may also, perhaps, be inferred that the motor cycling public is now content with much more moderate speeds than those which have recently been so prevalent. A cycle with a 3 horse-power engine may now be had, weighing altogether less than 1 cwt. The power in almost every case is derived from the petrol motor, and on the whole the workmanship displayed leaves little to be desired. It would seem, however, that the perfect internal combustion engine for this class of work should have better provision for cooling the cylinder than merely radiating gills. If water cooling is inconvenient on the bicycle, the provision of a fan should be a comparatively simple matter, without adding materially to the weight. It has been found in practice that, although the front side of the engine is kept cool enough when the bicycle is in motion, the hindmost surface of the cylinder shows a much higher temperature. Overheating of the cylinder walls tends to vaporise the lubricating oil, causing leakage of gas past and undue wear of the piston.
Experiments carried out some time ago by Professor H. L. Callendar showed very conclusively the gain in power which can be obtained from a small bicycle motor fitted with a fan. It was found that by running the engine on the stand at 2,000 revolutions without fan the temperature of the exhaust side rose to 570 deg. Cent. - a dull red heat - while the inlet side remained comparatively cool. After the provision of a fan the temperature on the exhaust side rarely exceeded 400 deg. Cent., even with the throttle full open, the spark retarded, and the engine running continuously. The fan was secured to the fly-wheel, and a suitable case conducted the air blast on to the engine. As the bicycle was not in motion it was decided, in order more nearly to approach the actual conditions on the road, to fit a second fan to blow on to the front of the engine, and it was then shown that with both fans at work the exhaust seldom exceeded 300 deg. Cent. or the inlet valve 70 deg. Cent.
It might be objected that the gain is purchased at the expense of the engine power, but it was found that not more than 1/25th horse-power was required to drive a fan which gave a blast of 25 miles per hour. With such figures before them motor cycle makers will do well to give this method of cooling close attention.
A new system of water cooling for motor cycles is shown by the N.S.U. Cycle and Motor Company, of Hatton-wall, London. The engine is of the vertical type, 4.5 horse-power, and the radiator is rectangular in section, and composed of a large number of tubes on the honeycomb principle. It is hung on the top tube of the cycle, and is provided at its rear with two fans, which are driven by a round strap from the engine crank shaft. The radiator carries about a quarter gallon of water.
One of the greatest novelties in the show is Howard's patent motor bicycle, the frame of which is practically the same as used on a standard safety machine. The motive power is supplied by a single-cylinder petrol engine of the horizontal type, and fairly large fly-wheel bolted to the tube in which the saddle pillar fits, and a bolt from the fly-wheel communicates motion to a pulley on the rear road wheel. Perhaps the most remarkable feature of this engine is the complete absence of a carburettor, the spirit being sprayed direct on to the stern of the inlet valve and being drawn into the cylinder with the air. The weight of the machine complete with a 3 h.p. engine is 90 lb. The engine is air cooled. A wide flange cast round the cylinder is drilled out with horizontal holes, through which the air is allowed to pass. The machine is built by Messrs. Mason and Brown, of Leicester.
Amongst variable speed gears a working exhibit is shown of Low's variable gear, which, although rather crude in construction, is simple, and has features which are desirable for motor car purposes. The gear consists essentially of a pulley, having two parallel grooves in which two separate belts can work, which is mounted on a countershaft between the engine and road wheel. The motor drives the twin pulley by means of a V belt running in one of the grooves of the latter, and the motion is transmitted to the road wheel by a second V belt running in the other groove. The twin pulley consists of a barrel mounted on ball bearings, and carrying at each end a fixed flange. Upon the barrel there slides a sleeve, which carries fixed upon it a third flange, whose outer faces form, with the inner faces of the two former flanges, the two V-shaped belt grooves mentioned above. This central flange is capable of movement in a direction parallel to the axis of the pulley, and it will be seen that, as it moves along, it recedes from one of the outer flanges and approaches the other one. The effect of this movement is to reduce the diameter of one belt-path and to correspondingly increase the diameter of the other one. The twin pulley is so mounted upon the machine as to be capable of a forward or backward movement, either by sliding along guides or by swinging in a frame or carrier. This movement is controlled by a lever, having a trigger and quadrant by means of which it may be retained in any desired position. The pulley being mounted, and with belts in position, the action is as follows: - Supposing the machine to be running, say, on any intermediate gear, the centre flange - being quite free to move sideways in either direction - will be in such a position that both belts are running at even tension. Now, if the lever be moved so as to move the pulley forward, the increased tension of the rear belt will at once cause the centre flange to move over towards the other belt, which, owing to its reduced tension, will allow the centre flange so to move over, until equilibrium is once more restored and the belts are running evenly as before; but the gear will have been lowered. If the pulley be moved backward the gear will be raised, always in exact proportion to the distance through which the lever has been moved.
Spring wheels for motor cars and cycles still have attractions for the inventive genius. Either from lack of knowledge or excess of enthusiasm, or a combination of the two, the inventors of these devices frequently state that by interposing springs somewhere in the wheel between the rim and the axle, all the good qualities of the pneumatic tire can he obtained without the attendant disadvantages. Of course, this is not the ease, since the solid tire cannot ride over uneven surfaces without lifting the wheel, if not the axle. The pneumatic tire, on the contrary, interposes an elastic cushion between the irregular surface of the road and the wheel itself, and this is effected by a continuous spring of compressed air extending round the periphery of the wheel. Thus no work is done in compressing springs. That the pneumatic is unreliable for motor car work is only too well appreciated, but many of the spring wheels which have been introduced only replace one source of trouble by another almost equally bad.
Perhaps one of the best attempts to produce a satisfactory elastic wheel has been made by the inventor of the Halle spring wheel. The principle on which this wheel is constructed may be explained by taking two parallel rulers and connecting them together, so that there are three rods joined by parallel links. If the two side members are held forcibly apart a considerable pressure may be sustained by the middle member. The result is that, as the pressure increases, the links form an angle and draw the side rulers towards each other against the outer pressure, which pressure, when the strain is released, tends to bring the three rulers into the original position again.
The main principle of the Halle wheel is as above described, but the side rulers are replaced by discs, and the centre ruler by a ring hub, while the links are provided with universal joints at either end. The side discs slide on tubes on the axle, and are forced apart by very powerful spiral springs. The universal joints allow the ring hub, to which the spokes are attached, to become excentric to the axle in any direction, but as the side discs must always remain at right angles to the axle, the ring hub, which must remain parallel to the side discs, must always remain at right angles to the axle also; no matter what position of excentricity it may assume. When weight or shocks are received by the wheel the side discs are drawn together by the links, forming an angle as the ring hub becomes excentric to the axle. Besides the main horizontal springs, the Halle wheels are fitted with auxiliary resilient springs, either elliptical or volute. The function of these springs is to provide increased comfort of travelling. These wheels are made by the Halle Spring Wheel Syndicate, Limited, Tunnel-avenue, East Greenwich.
Although there is an extensive display of motor cars, there is not much which calls for notice, most of the exhibits being already familiar to those of our readers who are interested in automobilism.
Sources: Graces Guide
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