All Prewar Motorcycles

overseas up to 1939

STANDARD BRITISH STANDARD TACHO MOTORCYCLE bsa, bsa norton triumph etc norton etc. 1940s to 1960s 1940s to 1960s

ALA. ARIEL MODELS STANDARD 2 1934-1948 STROKE SPEEDO

NOT WD MODELS Most models BSA, JAMES ETC.

Just different colours

w does it workf

Easy for you to say, but here goes - the CBG interpretation the workings of a Smiths chronometric speedo.

Put simply, the faster the cable spins, the further round the dial the needle goes. However, the complex truth is that the chrono movement provides a series of gears and clutches to calibrate the system so a given number of rpm at the cable always equates to a given movement of the needle. That's where it all gets complicated.

The gearwheels powered by the cable turn the escape wheel at the bottom of the camshaft. This movement is transferred to the balance weights which then oscillate at constant speed. The power from this oscillation re-transfers through the movement turning the escape wheel tooth by tooth. This mechanism controls the speed of the camshaft.

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  • max
    What ratio of prewar ariel speedo?
    6 years ago

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