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Tachometer Drive Gearboxes

The rev counter gearboxes we supply are of the ball race bearing type giving smooth silent out put.

These gearboxes reverse the rotation of the shaft to which they are attached.

Example Clockwise shaft gives anticlockwise cable rotation and vice versa. The rotation is determined by looking at weather the gear that is going to drive the gearbox, rotates clockwise or anti clockwise when viewed end on. Most British four stroke machines take the drive from the camshaft or magneto giving half true engine speed. Most common types used are 1/1 or 2/1 reversing gearbox.

Example Gear driven in anti clockwise direction at half engine speed would take 1/1 reversing gearbox matched to a 2/1 rev clock (Doubling cable speed) = true crank RPM Likewise a 2/1 reversing gearbox would match a 4/1 rev clock. It is assumed clockwise cable rotation is required at the tacho head WHEN VIEWED FROM ABOVE LOOKING DOWNWARDS..Some machines have clocks that require anti clockwise cable drive Examples are some Enfield twins, Triumphs,and Vincent’s Many part numbers have been used by Smiths in the past the ones below on the left replace previous ones used.

BG1508/04 = BG1507/08 =BG1508/00 1/1 REVERSING  =£120.00  

BG1508/06 = BG1507/02 = BG1508/08 2/1 REVERSING  =£120.00 

BG1508/03 = BG1508/03 4/1 REVERSING  =£180.00

BG1508/02= 1/1 NON REVERSING  = £120.00

BG1508/07=2/1 NON REVERSING    =£120.00