Coventry. Stand No. 98.
On this Stand a number of new Humber motor bicycles are shown. These have been expected for some time and will be examined with interest by everyone. The machines are extremely well designed and have several features peculiar to themselves, which should make them superior to many other motor-cycles in several ways. Only one power is made, namely, 31/2 .H.P.
The engine is a single-cylinder, bore 83 mm. and stroke 90 mm. Both valves are mechanically operated; ignition is by Bosch magneto; A.M.A.C. carburetter, handlebar control, rigid frame and spring forks are used. Transmission is by belt, and some of the machines shown have a two- speed gear; the speeds being about 4 to 1 and 10 to 1. No pedalling gear is fitted to any machine, but we understand that it will be possible to have pedals fitted to a single-geared machine in the near future. The price of the 2-speed machine is £45, and the single-speed £42. The petrol tank is made in two halves, which clip over the top tube of the frame, a nickel plated connecting strip being slid on before the saddle is attached, and holding the two halves of the tank together. The oil tank is carried under the right-hand foot-board, and the pump plunger has a strong spring underneath it, so when oil is required a simple pressure of the foot forces the charge to the engine, and the pump cylinder is automatically refilled. The change speed gear is contained entirely in the back hub. the low speed being held in by a pedal actuated brake band, and the top speed by a kind of internal expanding clutch, also actuated by pedal. A third pedal, or rather foot trigger, immediately releases the high gear when pressed. On the left-hand foot-board is another pedal connected to a metal to metal contracting band brake on the hub, and yet another pedal applies a back wheel rim brake. This description sounds somewhat as though the number of pedals was confusing, but they are so well arranged that this is not so in practice. Practically the right and left feet are always in position for applying the brakes. The right toe can be used for the oil pump, and the change speed is all done with the right heel. Needless to say, the machines are beautifully finished, and we should say they are very well worth their price.
Coventry. Stand No. 53.
The 1911 Humber motor-bicycles comprise the latest edition of the well-known 3 H.P. touring model and the 2 H.P. which was introduced during last season. In its simpler form, the 3 H.P., has a direct drive, and is fitted with pedalling gear, but the more characteristic equipment is that comprising footboards and a two-speed gear and free engine clutch constructed under the Hoc patents. In its present form both ends of the band which bring the high gear into operation are jointed. Hitherto one end has been anchored, and only the other end moved. The later construction, by increasing the dint of the operating mechanism should last for a longer time without calling for adjustment. The motor itself remains much as last year. The bore is below, while the stroke is above the average, viz. 83 mm. by 90 mm. The spark is obtained from a forwardly placed magneto, gear driven from the exhaust valve cam wheel. The carburetter is a Brown and Barlow, as on so many other high-class models, and this is set transversely close to the back of the cylinder. The craze for a dropped back frame has not been followed, and a low position for the saddle is obtained by mounting it on a pillar telescoping into the horizontal top tube. The cross-stayed handlebar is an excellent feature in these machines. The parts of the double tank are single sheet stampings, and enclose the top tube.
The new 2 H.P. lightweight is a particularly attractive machine. The little cylinder, with its 60 mm. bore, looks rather diminutive, but the way in which it has performed in hill-climbing, reliability and speed trials lie its appearance. Probably the comparatively long stroke - 70 mm. - and the off-setting of the cylinder have a good deal to say to the attainment of the power which is undoubtedly developed. It is interesting to see this practice of setting the cylinder in advance of the crank axis - which is fairly common in car construction - introduced into motor-bicycles. In this model the magneto, which is still gear-driven, is arranged just behind the cylinder. This involves a somewhat longer inlet pipe, but that is not wholly disadvantageous. The engine pulley is adjustable between 5.5 to 1 and 8 to 1, and a 5/8in. rubber belt transmits the power. The tyres, 14in. rubber studded Dunlops, are on the small side, but the weight is given as about 90 lbs. only. The petrol tank has a capacity of about a of a gallon.
In both models a spring fork of the Druid type carries the front wheel, and the outfit includes tubular luggage carrier, stand, and number plates. The 1911 Humber team is a very strong one.
Humber produced a a new 2.75 V-twin model of 339cc in 1911. The engine was unusual in having a master connecting-rod to which the second rod hinged. The Bosch magneto was gear driven and clamped to the rear of the crankcase, the carburettor by Brown and Barlow, and Druid forks were fitted.
At that year's TT races six machines were entered - all finished and one achieved victory.
3½ h.p. Model : 84 x 90 mm.; side by side m.o.i.v.; B. and B. carburetter; belt; Sturmey-Archer or Armstrong three-speed gear.
Humber, Ltd., Coventry.
Several improvements have been made to the 3½ Humber. In the, type which is designed for sidecar work, and which is shown attached to the latest Humber coachbuilt sidecar, a simple and strong form of kick-starter is employed, consisting of a chain sprocket with a single crank mounted upon a bracket brazed on to the off side chain stay. The bracket which supports the spindle also serves to carry the fulcrum of a very large and well-designed fibre foot brake.
A special mudguard forming a side extension to the rear guard is fitted to protect the belt. A very sensible-sized silencer is now used, and is placed forward of the engine, having a plain outlet pipe extending rearwards behind the bottom bracket. A1J the 3½ h.p. models are furnished with a crossbar for accessories between the grips of the handle-bars. In addition to the above, the 3½ h.p. model is exhibited with a fixed gear and also with a Villiers clutch hub.
2¾ h.p. Model : 60 x 60 mm.; side by side m.o.i.v.; B. and B. carburetter; belt; Armstrong three-speed gear.
The improvements which have been made in this machine are similar to those which have been outlined above and in previous issues regarding the 3½ h.p. model. This machine is shown in T.T. form, as well as with fixed and three-speed gears.
2 h.p. Model : 60 x 70 mm.; side by side m.o.i.v.; B. and B. carburetter; belt; Armstrong three-speed gear.
The lightweight remains unchanged for next year. Its features are already well known. The cylinders in this and all other Humber motor bicycles are considerably off set.