GB1558841A - Drive adjustment means - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO DRIVE ADJUSTMENT MEANS (71) 1. RICHARD CRADDOCK HAYES, a British Subject, of 65a Main Street, Kirby Muxloe, Leicestershire, do hereby declare the invention for which I pray that a patent may be granted to me and the method bv which it is to be performed to be particularly described in and bv the following statement: The invention relates to improvements in or relating to drive adjustment means, particularly for use in drive mechanism involving the use of a drive chain or belt.

In an arrangement comprising a chain or belt which co-operates with a pulley. toothed wheel or the like. it is frequently necessary to adjust the tension of the chain or belt. This may be because of dimensional changes in the belt itself causing it to become unduly slack. or possibly to assist in the replacement of the chain or belt which may be re-positioned in a slack condition and subsequently tightened.

The invention seeks to provide means for facilitating such adjustment.

The invention therefore provides means for adjusting a drive mechanism including a drive chain or belt. comprising a shaft on which is mounted a wheel or pulley, a disc or cylindrical block having an eccentric bore formed therein to receive said shaft for rotation relative thereto, and a sleeve member adapted to embrace and clamp a peripheral surface of said disc or block, said sleeve member being securable on a frame supporting the assembly. wherein rotation of the disc or block in the sleeve member alters the position of the axis about which the shaft rotates with reference to the frame and to a second wheel or pulley to which the first mentioned wheel or pulley is linked in use by said chain or belt, the disc or cylindrical block being provided on a flat or end surface thereof with an aperture, adjustment of the disc or cylindrical block being accomplished, when the said sleeve member is in an unclamped position, by inserting a rod-like member in said aperture and rotating said disc or cylindrical block relative to said sleeve.

Adjustment means according to the invention may be found specially useful, for example, in pedal-driven vehicles, bicycles or tricvcles. In such examples, a chain wheel is mounted in the cycle frame about a drive shaft operated by pedals, the drive shaft being eccentricallv mounted for rotation in a disc or block clamped in a selected position bv means of a sleeve mounted on the cycle frame. Releasing the clamp action of the sleeve enables the disc or block to be rotated bv insertion of a rod-like member in an aperture accessibly formed on a flat or end surface of the disc or block, thus effectively altering the distance between the pedal-driven shaft (and thus the chain wheel) and the hub of the rear wheel of the cycle. By this means, the tension in the chain may be adjusted.

The invention provides in another of its aspects a pedal cycle having means for adjusting a drive mechanism thereof according to the invention as hereinbefore described.

There now follows a detailed description of an adjustment means according to the invention. It will be understood that the description. which is to be read with reference to the drawings accompanying the provisional specification. is given by way of example only and not by way of limitation.

In the drawings: Figure 1 is a fragmentary side view of an adjustment means according to the invention: and Figure 2 is a perspective view of the adjustment means in use in a bicycle.

Figure 1 shows a toothed wheel 2, and a cycle chain 4 engaging with the teeth of the wheel 2 and linking it with the teeth of a hub wheel (not shown).

The wheel 2 is mounted in a bicycle about a shaft 6, driven by pedals 8 (one shown in Figure 2), so that the chain 4 causes the hub of the bicycle rear wheel (not shown) to rotate the propel the machine.

The position of the chain wheel is adjusted lengthwise of the bicycle with respect to the hub by means of the following arrangement.

A cylindrical block 10 is provided with an eccentrically formed bore 12. The shaft 6 is journalled in this bore, and the block received in a clamping sleeve 14 secured to a main frame portion 16 which also supports the hub of the rear wheel. The block is provided on its outer end surface with a recess 18 into which an adjustment peg (not shown) may be fitted when the tension in the chain is to be altered.

Release of a nut and bolt 20 on the clamping sleeve 14 allows rotation of the block 10 in a clockwise or anticlockwise direction to bring the shaft 6 into a position between a forward position shown in full lines in Figure 1 and a rearward position, shown in chain-dotted lines at 6' giving a position of the wheel 2 as shown in chaindotted lines at 2'. Once the selected position has been reached the nut is tightened on the clamp bolt 20.

Various modifications may be made within the scope of the invention, as defined by the appended claims.

WHAT I CLAIM IS: 1. Means for adjusting a drive mechanism including a drive chain or belt, comprising a shaft on which is mounted a wheel or pulley, a disc or cylindrical block having an eccentric bore formed therein to receive said shaft for rotation relative thereto, and a sleeve member adapted to embrace and clamp a peripheral surface of said disc or block, said sleeve member being securable on a frame supporting the assembly, wherein rotation of the disc or block in the sleeve member alters the position of the axis about which the shaft rotates with reference to the frame and to a second wheel or pulley to which the first mentioned wheel or pulley is linked in use bv said chain or belt. the disc or cylindrical block being provided on a flat or end surface thereof with an aperture, adjustment of the disc or cylindrical block being accomplished. when the said sleeve member is in an unclamped position, by inserting a rod-like member in said aperture and rotating said disc or cylindrical block relative to said sleeve.

2. A pedal cycle having means for ad justing a drive mechanism thereof including a drive chain or belt as claimed in claim 1.

3. Means for adjusting a drive mechan ism including a drive chain or belt substan tially as hereinbefore described with refer ence to and as illustrated by the drawings accompanying the provisional specification.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. The wheel 2 is mounted in a bicycle about a shaft 6, driven by pedals 8 (one shown in Figure 2), so that the chain 4 causes the hub of the bicycle rear wheel (not shown) to rotate the propel the machine. The position of the chain wheel is adjusted lengthwise of the bicycle with respect to the hub by means of the following arrangement. A cylindrical block 10 is provided with an eccentrically formed bore 12. The shaft 6 is journalled in this bore, and the block received in a clamping sleeve 14 secured to a main frame portion 16 which also supports the hub of the rear wheel. The block is provided on its outer end surface with a recess 18 into which an adjustment peg (not shown) may be fitted when the tension in the chain is to be altered. Release of a nut and bolt 20 on the clamping sleeve 14 allows rotation of the block 10 in a clockwise or anticlockwise direction to bring the shaft 6 into a position between a forward position shown in full lines in Figure 1 and a rearward position, shown in chain-dotted lines at 6' giving a position of the wheel 2 as shown in chaindotted lines at 2'. Once the selected position has been reached the nut is tightened on the clamp bolt 20. Various modifications may be made within the scope of the invention, as defined by the appended claims. WHAT I CLAIM IS:

1. Means for adjusting a drive mechanism including a drive chain or belt, comprising a shaft on which is mounted a wheel or pulley, a disc or cylindrical block having an eccentric bore formed therein to receive said shaft for rotation relative thereto, and a sleeve member adapted to embrace and clamp a peripheral surface of said disc or block, said sleeve member being securable on a frame supporting the assembly, wherein rotation of the disc or block in the sleeve member alters the position of the axis about which the shaft rotates with reference to the frame and to a second wheel or pulley to which the first mentioned wheel or pulley is linked in use bv said chain or belt. the disc or cylindrical block being provided on a flat or end surface thereof with an aperture, adjustment of the disc or cylindrical block being accomplished. when the said sleeve member is in an unclamped position, by inserting a rod-like member in said aperture and rotating said disc or cylindrical block relative to said sleeve.

2. A pedal cycle having means for ad justing a drive mechanism thereof including a drive chain or belt as claimed in claim 1.

3. Means for adjusting a drive mechan ism including a drive chain or belt substan tially as hereinbefore described with refer ence to and as illustrated by the drawings accompanying the provisional specification.