Title of the invention: Gear system

Technical Field

The invention is related to the gear system for the gear system of the bicycle arranged in the transmission housing on the crossbar in the area of the crankshaft.

Prior State of the Technology

Actually known gear system for the gear system of the bicycle arranged in the transmission housing on the crossbar in the area of the crankshaft consists (see WO 02/08050) of the axle fork with the tension pulley with the push lodgement on the guide link arranged between the shaft of the case and the crankshaft and in a parallel way with them with the assignation for the sliding of directly free-running chain pinion partly belted by the primary chain on the crankshaft and also for the shifts of the primary chain from one chain wheel of the case to the side chain wheel of the case with the linear motion of the axle fork on the guide link moved by the pull of any one from two control cables where any one is mounted to the one side of the axle fork.

The disadvantage of this relatively simple gear system with two control cables is: A) for every change of the gear there is necessary to outdo substantial friction forces in the own gear system but also friction forces between pulled second control cable and its conduh;'B) there are not exact adjustments of positions of the axle fork in relation to chain wheels of the ca&e and that is why there can be crossings of the primary chain between chain pinion and chain wheel of the case.

The Essence of the invention

Abovementioned insufficiencies are eliminated by the gear system for the gear system of the bicycle arranged in the transmission housing oiTthe crossbar in the area of the crankshaft by this invention the principle of which lies in the fact that, the axle fork is provided with the peg trenching on the spiral groove formed on the outside surface of the case by the rotary way due to the revolving mechanism set on the axle arranged in the transmission housing in a parallel

way with the guide link; that the spiral groove has got constant grade and is provided with the set of surfaces with the zero grade the number of which is equal to the number of chain wheels of the case; and that the revolving mechanism is formed by the shifting cylinder connected firmly with one face of the case and provided with the set of cutouts on its outside perimeter two of which are contacted by first ends of mutually counter spring-loaded two-ply swivelling levers set on the side of the transmission housing with second ends connected with control cables linked to the control lever.

It is necessary to see the essential fact for the gear system by this invention - the cutouts are formed by the gaps between axially oriented pegs arranged in regular distances at the outside perimeter of the shifting cylinder and every first end of two-ply Jevers has the form of the spring-loaded snap.

Another essential fact for this solution of the gear system is based on the shifting cylinder with the latching device oriented vertically to its axe of the rotation and formed by the spring- loaded snap.

The advantages of the gear system by this invention are: A) its easy and simple operating due to the elimination of the part of friction forces; B) the elimination of the possibility of the crossing of the primary chain due to the exact definition of particular positions of the axle fork.

Overview of the Pictures of the Drawing

The example of the particular performance of the gear system by this invention will be described in the following section with references to included drawings. Picture No. 1 shows axonometric view of the arrangement of gears in unseen transmission housing of the bicycle and of the lodgement of the axle fork from one side. Picture No. 2 shows axonometric view of the arrangement of gears in unseen transmission housing of the bicycle and of the lodgement of the axle fork from the opposite side. Picture No. 3 shows the side view of the transmission housing of the bicycle from the control side of the gear system.

An Example of the Embodiment of the Invention

The gear system (Pictures Nos. 1 and 2) of the bicycle is arranged in the transmission housing 8 (unseen on the picture) which forms the part of the bicycle frame. This transmission housing 8 shelters the crankshaft 6 and the shaft 4 bearing the case 5 of chain wheels. On the

crankshaft 6 there is axially movably set chain pinion 7 belted partly by the primary chain 187

The sliding of the chain pinion 2 on the crankshaft 6 is being ensured by the axle fork 1 with tension pulley 2 of the primary chain 18. The axle fork I is lengthwise rearrangeable on the guide link 3 arranged between the crank 4 of the case 5 and the crankshaft 6 in a parallel way with them. One of chain wheels of the case 5 is partly belted by the primary chain 18 by the position of the tension pulley 1 on the guide link 3 which is being ensured by the sliding mechanism.

The sliding mechanism is formed by the axle \2 set in the transmission housing 8 in a parallel way with the guide link 3. On the axle Y2 there is revolvingly set the case ϋ which has spiral groove K) with constant grade on its surface. The peg 9 formed on the axle fork 1 enters into the groove K> (see Picture No. 1). ,

The shift cylinder 13 arranged outside the transmission housing 8 and' provided 6y flie set of cutouts on its outside perimeter is firmly connected with the one face of tήe case ' Hl Two from these cutouts are contacted by first ends ^* of mutually counter spring-loaded "- elg. by the spring 20 - two-ply swivelling levers 14 set on the outside of the transmission housing 8 with second ends connected with control cables 15, 16 linked to the control lever situated e.g. on handle-bars of the bicycle.

The cutouts in the shift cylinder 13 are formed e.g. by the gaps between axially oriented pegs

17 arranged in regular distances at the outside perimeter of the shifting cylinder !3_and every first end of two-ply levers 14 has the form of the spring-loaded snap.

Hold-down mechanism 19 (see Picture No. 3) arranged at the perimeter of the shift cylinder

13 vertically to the axe of its rotation formed by the spring-loaded snap is also the part of the gear system.

The spiral groove 10 is advantageously provided with the set of surfaces with the zero grade the number of which is equal to the number of chain wheels of the case 5.

The change of the gearing is being ensured by the gear system of this invention by the following way:

The two-ply lever 14 is tilted in the direction S2 by pulling- of the control cable 15 by the _. control lever on handle-bars in the direction Sl (see Picture No. 3). Due to this the first end of the two-ply lever 14 turns the shift cylinder 13 in the direction S3. Because the shifting cylinder 13 is firmly connected with the case H, the case H is also turned due to thisT Turning of the case H begins through the spiral groove 10 axial sliding of the contacting peg 9 and also of the whole axle-fork 1 on the guide link 3. Together with the axle-fork 1 the

The list of used relation marks:

1-axle fork

2-tension pulley

3-guide link

4-shaft

5-case

6-crankshaft

7-chain pinion

8-transmission housing

9-peg

10-spiral groove

11-case

12-axle

13-shifting cylinder

14-two-ply lever

15-fϊrst control cable

16-second control cable

17-peg

18-primary chain

19-latching device

20-spring

Sl-direction

SlO-direction

S2-direction

S3-direction

SXl-direction