GB2117334A - Back pedal braking of cycles with derailleur gears - Google Patents

Abstract

Back pedalling of the cycle causes a pawl to engage the chain wheel and arrest its movement and cause the cycle brakes (which may be of caliper or hub type) to come into operation. Release of the pawl is by a hand operated cable and this allows the cycle to be wheeled or pedalled backwards. During forward movement the same cable holds the pawl in a freewheeling position.

Description

SPECIFICATION Coaster brake for bicycles with multi gear chain drive DESCRIPTION In havy traffic it is desirable to singnal with the hand -- precisly to say, with one arm directional changes or intentions to weave in or out of traffic (this signaling is law in some contries), leaving the cycler but one hand to steer, balance himself and to activate the one remainig brake as may be needed. This is a dangerous situation particularely in wet conditions.

In wet conditions caliper brakes, as generally in use, are very insufficient, braking effect is greatly reduced, the braking distance not only doubles or triples, but may be as high as ten fold experienced bicycle rider do know this. Though many improvements on caliper brakes have been made in the last few years, a greatly increased brake path in rainy situations is still with us.

Foot actuated coaster brakes are more efficient according to the strong leg power available. By that reasons several inventions have been made for bicycles with multi gear chain drive; nevertheless, none came in common use. So most of these inventions are workable, they invariable need special ingeneering to one ore more of the various components of a bicycle such as the rear wheel hub or the axle of the cranks, plus several of them effects a blokking of the rear wheel, when braking process goes to a total stop.

Foot actuated coaster brakes have several distingt advantages over hand squeeze grip due to the strong leg power available plus the longer distance of its pressing. This invention however functions on said bicycles without alterrations of the existing parts. It can be offered as standart equipment or as an accessories item for the allready existig ones on the market, not only are there no changes riquired; the biocking of the rear wheel in a "total stop" situation is prevented; plus the bicycle can be moved backwards, without lifting the rear wheel - that last fact is also known to all experts. With this invention cyclists who appreciate the advantage of multi gear chain mechanism, can now also enjoy the advantage of a coaster brake.

BRIEF DESKRIPTION OF THE DRAWINGS Fig. 1 shows a side view, which explains some techniques of the present invention.

Fig. 2 is a section according to Fig. 1, showing the rear freewheel assembly.

Fig. 3 explains the safety part 55, how it is built and how it operates.

Fig. 4 is a side view of an embodiment, when the invention works with a rear wheel hub brake.

Fig. 5 shows the needet parts, when the invention goes to a caliper brake with sidepull.

Fig. 6 shows a bicycle having a tangential system of the invention, wich is fully enclosed.

Fig. 7 is a detailed drawing of an embodiment, where the power is going tangential from the greater chainwheel.

Fig. 8 shows the hook lever system.

Fig. 9 shows single presentation of Fig. 7.

DISKRIPTION OF THE PREFERRED EMBODIMENT One object of the invention is to take the motive Power directly from one chain wheel, situated on the axle of the cranks, or from a similar wheel with special formed teeth for a ratchet system; that wheel is adequate fastend by the side of one chain wheel, the said power is transmitted to the brake wich is allready on that bicycle; be it a caliper brake, an inclosed rear wheel hub or another brake system.

One example of operation is shown in Fig. 1, the power is here taken from the smaller diameter chain wheel, mountet inside the larger. This is of great cosmetic value, the invention is mostly hidden by the main chain wheel, and thus does not interfere with the graceful lines, bicycles should have. On cable 2, leading to the brake, is fastened item 3 wich ist kept upwards by the spring of of the present brake or an additional spring. Its correct inactive position is achieved by the enlarged upper end, equipped with plugs fitting into slots on the lower monting plate, wich is fastened on the horizontal chainstay tube together with its counterpart, the upper mounting plate, by two nuts and bolts, as shown in Fig. 1.

Proper alignment is made before the monting plates are tightly secured. The upper mounting plate holds part 2-b in a tiltable manner to allow cable 2 easy alignment. The tiltability of part 2-b is not necessary when factory equipped.

Item 3 may be fastened in a pivot-like way on an arm wich is turnable on the axle of the cranks or on the housing of the axle. This arm may also be pliable mounted as shown in Fig. 7, part 30, where part 30 is made flexable, allowing to follow the circular motion of the chain wheel for several centimeters.

Item 3-a is a console from part 3, bearing the pivot of part 4 at position 40. Part 4 has on its upper end the chainroll 421 which is wide enough to go from part 3 over the sprockets of the chain wheel item 1, and over 3-a. The arm 41 is formed that it guides 421 into the sprockets by gravity when pedaling backwards. Item 411 is a felt-like pad fastend on 41 and glides on the smooth rim of item 1, keeping 421 free from the sprockets when driving, but causes engaging when motion is reversed.

Should the apparatus be enclosed, there must be an opening approxemately where the symbol of gravity is drawn, large enough to allow arm 41 to be lifted. There are multi gear chain drive systems in use where the chain can not be guided over the largest chain wheel and over the largest cog of the rear freewheel assembly simultaneously, for the chain is too short. Attempting or accidental shiftig the derailleurs, with some force on the pedals, will bring the chain to extrem tention, blocking the whole mechanism; the driver has to disembark and untangle it. On a bicycle equipped with this coaster brake as discribed so far - wich is the "automatic mode" - the entanglement can only be corrected when lifting arm 41, with a finger tip.

A further prototype is also shown in Fig. 1: Part 421 is guided by the items 42 through 45. Item 42 glides along the sprockets during forward motion and 421 is kept out of contact because it is connected with 42 by 45; item 42 is kept in its position by 44 wich is pivotet in part 3 at point 43.

in braking mode, 421 engages because 45 pushes 41, as can be concluded, looking at Fig. 1.

A so equiped bicycle has a perfect coaster brake, however backwards pedaling is not possible and pushing the bicycle backwards is only done while lifting the rear wheel. The former is not possible at any bicycle equipped with coaster brake, and the later is not important anyhow, for bicycles are ment to be driven forward, not back. Therefore a version has been developed effectivly eliminating theese two points, it is also shown in Fig. 1. The braking process is initiativated with a hand lever. Because said bicycles have two attractive levers on the handle bar, activating the front and the rear brake, no one would like to take one off; we can therefore use the existing rear brake lever to activate the initiative for 421,because mentioned lever is connected with the rear brake and our apparatus too.

This prototype with "hand-initiative" mode shall be described: The arm 44 is now pivoted at its point 43 in an exenter, a flip-flap, or similar executed mechanism which shifts 43 to the left or downwards so that item 42 leaves contact with the sprockets, but remains under tention within a small distance from the sprockets. By pulling the responsible handlever a small distance of some millimetres, to bring the braking parts close togather; without actually braking, than the extention 2-c pushes arm 41 - wich in turn moves 421 into the sprockets. At this moment the braking -- ability may be taken over the legs in usual manner for coaster brakes, braking may commence or the brake may be held in readyness and the hand is free again.The change from "automatic" to "hand-initiative" must be made in an either - or mechanism, like or similar part 431 in Fig. 9.

The rear derailleur allways keeps the upper portion of the chain under light tension, causing the rear wheel to block when braking goes to a total stop; this problem is solved by stopping the rear freewheel assembly before the parts of the brake system are really pressed togather, before the brake takes effect. Stopping the cogs of the freewheel assembly gives the upper chain portion some slack when the braking process goes on; stopping must not be absolute but allows sliding, when needed it must glide in case the slack in the lower half is not long enough to provide the whole distance of the backward turn in the braking process. This might be possible when the derailleur system is allready worked over, and several parts might be modified and are other than original factory design. It might also happen if the invention goes to a rear wheel hub brake (see Fig.

4.) and parts 5 through 54 are not properly mounted. All this is achieved in the beginning when item 1 is engaged with item 4 and turns the few millimetres downwards, wich are provided by the space between the endknob of cable 2 and part 3 in Fig. 1, and is also recognizable in Fig. 9.

The relative long distance between the chain wheel and the cogs is usefull and advantages the sudden stopp of the cogs. Fig. 7 and Fig. 8 show how part 51 can be pressed through one sole rod, bend on one end, closely following the chain stay tube, and through its spring-like proberty, providing enough elasticity for the whole braking action. In case of a hub wheel brake as Fig. 4, an additional elastic part may be inserted between part 3 and part 5.

The construction of the safety part 55 is shown in Fig. 3, it serves only as an emergency release in case the items 5 through 54 could have been destroyed somehow, its fingertip lever will release the blocked brake.

Simply lifting the arm 41 Fig. 1 allows the bicycle also in "automatic" mode to be pushed backwards without lifting the rear wheel.

Therefore is planed an additional release mechanism wich has its activating button mounted on the seat tube near the saddle; and by touching this button, the bicycle may be mouved backwards. This mechanism operates independently from the invention because there is no linked connection to 41; and any destroying of this additional mechanism disturb, has no effect to the invention.

The transmission of the brake force to the existing brake by use of cables or rods, is well known and needs no further elaboration. Caiiper brakes are side or center activated with cables.

Fig. 5 shows side pull, using parts 21 and 22; for center pull, the connection is even simpler and no discription is required -- it is assumed that manufacturers of caliper brakes will somewhat alter their brakes, also in consequence the stronger force now available.

The connection to a rear wheel hub is shown in Fig. 4. Next to the smalles cog, a mechanism is placed, having similar effect to one cog as parts class 4 to the chain wheel item 1 in Fig. 1. Around the base plate 60, wich is fastened on the axle and whose accurate postion is achieved by its console like part fitting into the space of the axle plate and by clamp to the rear fork = rear part of the chainstay tube, turns the base ring 61. Item 61 is kept clockwise tention in its position by coil spring 62 pressing the plug 63 against the said console from item 60. Item 62 allows a turn of about 900.

Part 64 holds on its lower end link 421-a similar to 421 shown in Fig. 1. Lever 65 is pivoted in 61 and linked with 64. A spring pushes 64 in fore position, the power of theese both springs is relativ that wise allowing turn 61 only after 421-a has engaged. Other methods of engaging 421-a are possible as discribed in connection with the chain wheel (Fig.1 .). The reverse turn of the free wheel assembly is acceleranted through the circumstances of 65, allowing cable 2 a shorter way, but full power 66. at point Part 61 may be formed into a guide at 67 to additional assure disengagement.

In this application the rear cogs must be arrested after the braking motion has started, pressure from 51 Fig. 2 acts after certain reverse motion has been made. This delay can be built between Item 3 and 5.

A wheel with special designed teeth, as explained with the power transfer from item 1, may be also added nere, or exchanged with the smallest cog. Use of a ratchet wheel here, as well as with the mentioned chain wheel, allows somewhat simpler parts for 421 and 421-a.

Drawings shows 421 allways as a role, a role like the links of bicycle chain -- however 421 must not be a role when engaging with original sprocket wheels, it can be a plain part as well having the advantage of a larger contact in the lengh to a tooth.

This brake may be added to existing bicycles in which case the parts are fastened to various frame members by use of steel band type clamps which might be reinforced by use of modern cement, thereby obtaining the required strength; Fig. 7.

shows a special way for fastening on the often very thin end of the chain stay tube by adding a cotter between the steel band and the tube.

Seperate front and rear wheel brakes are not mandatory everywhere: both wheel may be braked simultaneously, this is a simple extention.

And there are theories which claim advantage for frontwheel braking, who want to take this chance: the items class 5 may be omited, and the mentioned release mechanism too. These parts may also be omited on professional racing bicycles, resulting a very light-weight version. Bad experiences with the existing brakes on bicycles with multi gear chain drive led to this invention over mny thousend miles for weeks through some contries several prototypes have proved themselves.

While the invention has been described and illustrated, the same is to be considered as illustrative and not restrictive in character, only the preferred embodiments have been shown and described and that all changes and modifications coming within the spirit of the invention are desired to be protected.

Claims (2)

CLAIMS In combination with a conventional bicycle having a multy gear chain mechanism with derailleur system, I claim:

1. A ratchet like lever is guided by the threader mechanism (41,42,43,44,45 and 411) in proper funktion into the teeth of one large chain wheel when forward motion is reversed and the legs power effects the brake sytem after the cogs are arrested (51).

said treader mechanism keeps said lever in silencing or noiseless freewheeling position when forward motion, said freewheeling position can be eliminated (431), said elimination can be restored by move a hand lever on the handle-bar.

2. The combination of claim 1, further comprising besides the said large chain wheel is fastend a similar wheel special toothed, wherein said funktions work.