STAR ONE SPEEDS A LOTOne of the problems of a pedal of a drive of the bike was and still remains the need to change torque to the driving wheel depending on road conditions. And I must say that the designers decide, but in many ways They even created planetary drive bushings, however they are complicated and therefore not cheap. So often on the rear wheel set of the multistage transmission with more asterisks and mechanisms for the transfer and payment chain length. This is the most waste and inexpensive option. But the number of stars (usually three. sometimes four) is sometimes not enough. Then to increase the number of “speeds” leading asterisk also make two – and even three-stage.

What if the solution to this problem is to limit, again only one star, but now leading — it is large, it is possible to experiment in a wider range, and it is “at hand”, or rather under the feet. And in order not to group a block of a few stars — make one, with a variable diameter. But how is that possible? I think so! Here is a crucial idea to use when transmitting the torque from drive sprocket to driven simple device (a kind of CVT) installed in place of the large sprocket on a normal road bike, I want to share with readers.

The essence of this device is that the drive sprocket is cut into four sectors that through multi-stage Cam is simultaneously moved apart symmetrically in all directions (or move back), changing the gear ratio of the drive. But the problem here is that sectors covers not the belt and chain, and how to push? Then with the teeth leave only two opposite sectors to ensure the transfer of torque, and the other pair of sectors the teeth are cut, it will be used only for the support and direction of the chain. Now, when one of the sectors with teeth will be released from engagement by manual turning of the Cam sliding (shifting) sectors by modifying the torque. But you can almost do without the support of smooth sectors. Then the chain will cover “quasielliptical” circuit. Thus, there is still the idea of the elliptical sprocket, as is well known, significantly improving drive efficiency.


Multi-speed sprocket

Multi-speed sprocket:


1 — right rod; 2 — guide disk; 3 — lobe Cam; 4 — arm pivot Cam (wire 04, 2pcs); 5 — chain; 6 — normally compressed spring; 7 — a gear sector (from 28 leading-bevel sprockets child Bicycle 2); 8 — the lever (2); 9 — finger mounting lever to the drive (2 PCs); 10 — carriage shaft; 11 — bolt sector to lever (2 PCs.); 12 — screw fastening sector to lever with pin (2); 13 — remote washer (2 PCs.)

To set this two-sector sprocket on any bike instead of the standard, providing a simple chain drive spring-compensator lever near the driven sprocket.

So, the design of the device. First, we note that all the parts — steel, flat and made of 3 mm sheet.

To the interior of the carriage head staff of the right connecting rod is welded to the guide disc diameter 260 mm disc symmetrically at a distance of 65 mm from the centre rigidly mounted (welded) two axles, each of which is pre-insert remote disc (thickness slightly more than the Cam) loosely fitting the lever. To each arm through the washer two screws screwed devicesby sector cut from a standard 28-bevel the leading star of a children’s bike. The screws are located closer to the axles on the ends have grooves (pins) that come into contact with the ledges of the Cam-lobe multi-stage loosely placed on the carriage shaft. To rotate the Cam to its latest projections welded to the arm. The screws to the pins of both levers (and hence the toothed sectors) strapped between a normally compressed coil spring. The depth of the ledges of the Cam in the process of pre-Assembly and adjustment is adjusted with a file in such a way that the first teeth of the sectors freely entered into the chain links. With the same purpose (to make the chain suddenly jumped, not hitting on the first tooth) to it welded antennae — the guides. To at maximum opening of the sectors tendrils clung to the frame of the bike, they should not be wide. In the extreme case can a little with a hammer to tweak the frame.

To shift gears, we must first position the rod so that one of the sectors out of engagement with the chain. Bending down, rider’s right hand arm deploys multistage lobe Cam on one or more ledges, increasing (or decreasing) thus the transmitted drive torque.

Since the total difference of the chain links with a maximum extendable toothed sectors, and with minimal shift is 16 pieces, then the drive is also required spring-roller compensator changes the length of the chain. The compensator consists of a rigidly fixed on the rear fork of the frame bracket and the hinge (the axis) it is suspended on a pivoted lever. At the ends of the lever on its axis is equipped with two roller ball bearings 201, “compressed” washers for the direction of the chain. One end of the lever connected to the frame of the spring stretching.

Compensation mechanism changes the length of the chain

The compensation mechanism changes the length of the chain:

1 — right rod; 2 — guide disk; 3 — arm rotation of the Cam lobe; 4 — chain; 5 — right rear pen villageoil (tin s0,5); 7 — spring (from the old expander); 8 — bracket (STZ, sheet s); 9 — pivot arm (STZ, sheet s); 10 — restrictive washer (4 PCs); 11 — drive sprocket rear wheel; 12 — roller (bearing 201, 2 PCs.)

Are here, of course, better with manual brakes, but you can foot. On the rear fork of the frame should be set in addition ageological made out of tin, which prevents sagging part of the chain between the wheel and the frame. The compensator arm will be rested in the pen plug back on after braking under the action of the spring.

To ensure the operation of the device must be well lubricated all contact surfaces and links.

Vladimir GAVRILOV, the item of Inozemtsevo, Stavropol Krai

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