Debenham Sisters
Betty and Nancy Debenham, with their dog, Poncho, were keen motorcyclists. Nancy won a Gold Medal at Brooklands in 1926.
The Debenham Sisters
Another Counter-shaft Gear.
The Bowden counter-shaft gear is a new introduction designed to fit existing models. The gear case is provided with a bolt and nut and two slotted plates, which enable the box to be attached to the bridge of a standard frame as illustrated by the sketch of the complete gear fitted to a 3 ½ h.p. Chater Lea Minerva. Reference to the sectional drawing of the gear fig. 3 shows the chain wheel A and sleeve A1. These receive the power from the engine-shaft by means of a roller chain and transmit it to the clutch centre B. On the central shaft or clutch centre are mounted two gear wheels D and G, and on a separate spindle and formed solid with it are another pair of gear wheels E and F. H is the belt pulley which conveys the power to the road wheel. It will be noted that this is exceptionally large in diameter, centre to centre of belt being 7in. Belt slip should therefore be almost impossible. The operation of the gear is extremely simple. In the centre of the clutch is a wedge bar J J, which is longitudinally operated by means of a cam clutch shown in fig. 2. When the bar J is moved to the right and the spring K expanded, the clutches C C are forced upwards, locking the gear wheel G and belt pulley H to the counter-shaft. In this position the shaft carrying the gear wheels E and F revolves idly. This is the normal or high gear position. When the pedal clutch is moved to the low gear position, the spring K contracts and the bar J is forced to the left, the other pair of clutches move outwards, and the gear wheel D is locked to the counter-shaft, and driving the pair of wheels E and F, the power is transmitted to H through G, and the belt pulley revolves at a slower speed than the counter-shaft, this is the low gear position. The reduction in gear ratio is brought about by the difference in the diameters of the four wheels D E-F G, the gear train being arranged in a similar manner to the back gear of a lathe.
With a 7in. diameter belt pulley on the counter-shaft and a 19in. belt rim and the standard chain sprocket on the engine-shaft and counter-shaft the top gear is about 5 to 1. The engine sprockets can be supplied with 15, 16, 17, and 18 teeth, the counter-shaft sprocket having 28 teeth. The starting device consists of a segment of a gear wheel P, meshing with a small toothed wheel on the counter-shaft. The segmental wheel carries a crank and pedal, and by kicking downwards and backwards the engine is revolved two and a half times to one-half revolution of the pedal starter.
The Bowden Wire Co. inform us that on test they can start a single cylinder 3 ½ h.p. Minerva or an 8 h.p. Bat-Jap with certainty by one thrust down of the crank. Although designed for a standard 500 c.c. engine, the gear has been thoroughly tested on an 8 h.p. J.A.P. to find any faults there may be in the construction. This policy of trying the gear on a machine with a higher powered engine than the standard 3 ½ h.p. is to be commended; if it will stand an 8 h.p. engine it should be perfect with a lower power.
The whole of the bushes are made of phosphor bronze, the gear case is of aluminium, and the teeth, which are 8 pitch. are of hardened steel, also the shafts. The gear box is lubricated with Price's hub grease, the filling tap being at the top. and a drain off screw at the bottom.
The gear was weighed in our presence, the total weight being 15 lbs. in addition to the pedal control already described, the gear can be controlled by a Bowden wire and lever with ratchet fitted on the top tube. One of these gears was fitted to the 4 ¼ h.p. Ixion-Precision ridden by W. R. Jones in the Quarterly Trial last Saturday.
The counter-shaft type of gear is certainly growing in popularity, and the enterprise of the Bowden Wire Co., in marketing a gear which can be fitted to almost any standard model, will doubtless receive its just reward in the form of an extensive demand.
1911 Olympia Show - The Motor Cycle October 19th, 1911. Page 1100B
