GB2061468A

GB2061468A - Control Switch for a Cycle Dérailleur

Info

Publication number: GB2061468A
Application number: GB8033201A
Authority: GB
Original assignee: Hurst R H M; Huret et ses Fils SA
Current assignee: Hurst R H M; Huret et ses Fils SA
Priority date: 1979-10-19
Filing date: 1980-10-15
Publication date: 1981-05-13
Also published as: GB2061468B; IT1146215B; DE3039024C2; FR2467767B1; JPS5667683A; DE3039024A1; FR2467767A1; IT8049933A0

Abstract

A control switch for the dérailleur of a cycle in which the gear change lever is mounted to pivot with friction on a bush 3 which is itself mounted to rotate on the pivot 4, the coupling of this bush with the pivot being limited by stops defining the angle A of pivoting of the lever with play. <IMAGE>

Description

SPECIFICATION Control Switch for a Cycle Derailleur The invention relates to a control switch or selector for the derailleur of a cycle.

Control switches, which by means of a cable ensures the movement of the chain-guide pinion and of the chain-tensioning pinion transversely to the freewheel of a cycle, comprise a lever pivotally mounted on an axis so that, by angular pivoting of this lever connected to the cable, the chain-guide pinion and the chain-tensioning pinion are shifted transversely so as to position them in the plane of the selected freewheel sprocket.

This pivoting of the lever so as to select a freewheel sprocket takes place against a frictional torque determined by a friction member, which as a rule is adjustable, arranged on the switch so that the lever remains in the selected angular position.

It is also known to design these control switches in such a way that the lever is able to pivot "freely" through a small angle for each of these selected positions, this being so as to take into account the lateral play in the chain, which play increases, moreover, as this chain wears.

Therefore, when the cyclist operates the lever of the switch, in particular in order to transfer the chain from one sprocket to a larger sprocket, it moves the chain-guide pinion and the chaintensioning pinion beyond the selected freewheel sprocket by a distance depending on the angle of play of this switch, so as to compensate for the lateral play in the chain.

The chain thus passes rapidly and precisely on to the selected sprocket and when the cyclist releases the switch lever said lever pivots in the opposite direction under the action of the spring or springs of the derailleur through an angle corresponding to the play in the switch, so that this lever is situated in a selection position for which the chain-guide pinion and the chaintensioning pinion are arranged precisely in the plane of the selected freewheel sprocket.

However, in these known switches the frictional torque provided to maintain the switch in the chosen selection position affects the freedom of this lever to pivot through the angle of play intended to compensate for the lateral play in the chain.

Therefore, the more the frictional torque is increased to resist the adjusting spring of the dérailleur, the less this lever is able to pivot freely to compensate for the lateral play in the chain.

With the known switches it is thus necessary to arrive at a compromise between the value of the frictional torque acting on the lever and the freeness of play of this lever, for if the frictional torque is considerable so as to resist effectively the action of the adjusting springs of the dérailleur, the freeness of play of the lever is reduced and the adjusting springs of the derailleur are no longer powerful enough to restore the lever to the normal selection position by causing it to pivot through this angle of play.

In this case the chain-guide pinion and the chain-tensioning pinion are maintained in a plane situated beyond the chosen freewheel sprocket, thus causing crunching of the chain on the sprocket, accelerated wear of the chain and, possibly, even disengagement of the chain from its sprocket or the passing of this chain on to an adjacent sprocket.

The present invention has, in particular, the object of eliminating these disadvantages and for this purpose relates to a control switch or selector for a cycle dérailleur, the operating lever of which, provided with means for securing a cable, is pivotally mounted about a pivot and, on the one hand, is subjected to a frictional force maintaining the lever in the selected pivotal position and, on the other hand, is connected to the pivot with play which allows, in the selected pivotal position, the pivoting of the lever through a small angle, which switch is characterised in that the lever is mounted to pivot with friction on a bush which itself is mounted to rotate on the pivot, the coupling of this bush with the pivot being limited by stop members defining the angle of pivoting of the lever with play.

According to another feature of the invention, the bush comprises, at one of its ends, a flange against which the lever is applied laterally, the other end of this bush being provided with a threaded portion receiving a nut for adjusting the friction of the lever on the bush.

According to another feature of the invention, the nut is applied laterally against the bush by means of a washer provided with at least one tab fitting inside a longitudinal groove provided in the threaded portion of the bush.

The invention is illustrated non-restrictively by way of example in the accompanying drawings, in which Figure 1 is a partly sectional view of a switch according to the invention; Figure 2 is a section along the line A-A in Figure 1; Figure 3 is a view in the direction of arrow F in Figure 1, the friction-adjusting nut being omitted.

Accordingly, the present invention has the object of devising a control switch for a dérailleur, which is of simple design and in which the frictional torque can be adjusted to a value which is as high as desirable, without thereby altering the freeness of movement of this lever through the angle of play.

This switch comprises a lever 1 which is provided with holes and grooves 2, and 22 for securing the pull cable which is connected also to the derailleur of the bicycle, said lever being mounted to rotate on a bush 3 which is itself arranged on a pivot 4.

The pivot 4 has a head 4, locked in a local deformation 51 of a strap or clip 5 which is fixed on to a tube of the bicycle frame.

This lever 1 is maintained in lateral application at 7 against a circular flange 8 of the bush 3 by tightening a wing nut 9 acting on a wearing washer 10 by means of a washer 11 secured against rotation relative to the bush 3.

For this purpose the washer 11 has two tabs 1 1, which fit into grooves 31 of corresponding dimensions and formed longitudinally on the threaded end 32 of the bush 3.

A plate 12 is fitted on the local deformation 51 of the clip 5, which plate has flanged portions 1 2, and 122 limiting the farthest deflection of the lever 1.

On this plate 12 and coaxially to the pivot 4 there is formed a square plug 123 which fits into a recess 1 3 in the shape of a four-pointed star, which recess is provided in the flange 8 coaxially to the pivot 4.

The length of the bush 3 is such that when it is arranged on the pivot 4, the square plug 123 being situated in the star-shaped recess 13, the threaded end of this bush 3 is positioned slightly set back relative to the end of the pivot 4 so that the screw 14, which is locked on the pivot 4, retains the bush 3 laterally while allowing it to turn freely within the limits of the play of angle A, which are determined by the angle at the apex of the sides of the star-shaped recess 13.

The mode of operation of this switch is as follows: When the cyclist actuates the lever 1, so as to operate the derailleur and shift the chain from one sprocket to a larger sprocket, this lever 1 firstly causes the bush 3 to rotate through the angle A, this being only against the restoring force of the springs of the derailleur transmitted to the lever by the cable secured in the hole 2,.

In fact, during this first movement, the lever 1 is firmly connected with the friction assembly formed by the washer 11 and the wing nut 9 mounted on the shaft 3.

Subsequently, at the end of this pivoting through angle A, one of the flanks of each of the sides of the star-shaped recess 13 is applied against each of the edges of the square plug 123 of the plate 12 and the bush 3 is thus fixed in rotation.

Continuation of the pivoting movement of the lever 1 then takes place in opposition to the restoring force of the derailleur springs, to which is added the frictional force created by the application of the washer 11 against the washer 10.

When the speed change of the derailleur has been effected, the cyclist releases the lever 1 and the latter pivots in the opposite direction through an angle A until Ithe opposite flanks of the sides of the star-shaped recess 1 3 are applied against the edges of the plug 123.

The lever 1 then remains in this selected position, in view of the fact that the frictional force determined by the tightening of the wing nut 9 is greater than the restoring force of the derailleur springs.

It is quite apparent, therefore, that in this design the frictional force does not affect in any way the freedom to pivot through the angle of play A, said frictional force being determined solely by the tightening of the nut 9, taking into account the substantial friction surfaces provided by the abutment surface 7 of the flange 8 on the lever 1 and by the abutment surface of the friction washer 10 against the washer 11.

Furthermore, the frictional force set by the tightening of the nut 9 is not liable to be put out of adjustment by loosening of the nut 9 during actuation of the lever 1, since this nut is not in direct contact with the lever but is in indirect contact by means of the washer 11 which is secured against rotation relative to the bush 3.

Similarly, it is evident that this control switch is very robust and therefore has good reliability, in view of the fact that during the actuation of the lever the flange 8 is applied with substantial contact surfaces against the edges of the plug 1 23, the application forces of these surfaces being distributed coaxially to the shaft 4.

Claims

1. Control switch for the derailleur of a cycle, the operating lever of which, provided with means for securing a cable, is pivotally mounted about a pivot and, on the one hand, is subjected to a frictional force maintaining the lever in the selected pivotal position and, on the other hand, Is connected to the pivot with play which allows, in the selected pivotal position, the pivoting of the lever through a small angle, which switch is characterised in that the lever is mounted to pivot with friction on a bush which itself is mounted to rotate on the pivot, the coupling of this bush with the pivot being limited by stop members defining the angle of pivoting of the lever with play.

2. Switch according to Claim 1, characterised in that the bush comprises, at one of its ends, a flange against which the lever is applied laterally, the other end of this bush being provided with a threaded portion receiving a nut for adjusting the friction of the lever on the bush.

3. Switch according to Claim 2, characterised in that the nut is applied laterally against the bush by means of a washer provided with at least one tab fitting inside a longitudinal groove provided in the threaded portion of the bush.

4. Switch according to Claim 1, characterised in that the stop members defining the angle of pivoting of the lever with play are formed between the flange of the bush and a plate fixed in rotation on the pivot, the plate being provided with stop flanged portions defining the angle of pivoting of the lever with friction.

5. Switch according to any one of the preceding Claims, characterised in the stop members defining the angle of pivoting of the lever with play comprise a plug arranged in a recess and disposed coaxially in respect of the pivot, the plug being designed in the shape of a regular polygon arranged in a recess designed in the shape of a regular star, the number of points of said star corresponding to the number of sides of the polygon.

6. A control switch for a cycle derailleur substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.