MODES OF POWER TRANSMISSION.
The crank-axle, and crank-bracket, the “heart” of the bicycle, is now the place where the power is first exerted, and from this it must be transmitted to the wheel. There are a number of possible methods of transmission, thus:
1. A leather belt.
2. A metallic band with holes to engage projections on the sprockets, or provided with projections to enter holes therein.
3. A chain.
4. A wire rope, with or without projections.
5. Clutch or ratchet action, at one or both ends, operated by a lever.
6. Lever and crank, with or without an oscillating fulcrum.
7. A connecting-shaft, carrying bevel gears at each end.
8. A connecting-shaft, working pin-and-roller gears.
9. A connecting-shaft, with universal joints.
10. A row of spur gears to close the gap between the two axles.
11. Cranks and connecting-rods, working double, locomotive-fashion.
12. Friction wheels, with or without spur gears.
13. Pneumatic or hydraulic transmission, with some choice of fluids.
14. A combination of cams and rollers.
15. Balls working in spiral grooves on axles.
This does not exhaust the list of theoretical possibilities, nor mention all the combinations which could be formed. A sufficiently wild inventor could fix up a contrivance, beginning at one axle and ultimately reaching the other, which involved the whole list, and he might then be confident that he had met the long-felt want.
Nos. 2 to 4 are modifications of No. 1; No. 5 involves giving up back-pedalling; No. 9 cannot “gear up;” Nos. 12 to 15 are not practical. And the whole list—just as the large number of “mechanical powers” named in old text-books are really only two—“boils down” to five: the endless belt, the spur gear, the shaft with bevel or pin-roller gears, cranks and connecting-rods, and the lever. The fourth of these appears on only one make thus far; it involves practical difficulties, is not strictly chainless, and hardly need be considered as a rival to the chain. The lever is not seriously contesting now. The spur gear is in market; yet it is offered in only two or three patterns now, one of them the [Hildick], which has distinctive claims of its own—and so it can be passed. The third of these just named is the contestant of the old chain, against which it has brought an action for ejectment, to be tried, and probably sustained or dismissed, in this year 1898.