Pre Unit Gearbox ratios

[watts]

Hello

I am trying to work out which type I have.  I understand different gears can or were fitted depending on proposed use.

I assume it is possible to work this out from turning the input and output shaft and seeing those ratios.

I get this.

Input revolutions to output revolutions

0.75:1.00
1.25:1.00
2.00:1:00
3.00:1:00

Output accurate, but input and error of 0.10 ish

This not even be a sensible thing to do.

Is there an easier way other than dismantle it.

Best wishes
Matthew
                   

[DAVE BRADY]

Hi,

Pre-unit B31/B33?  Does the gear box have letters stamped on the inner cover?  STD for standard, RR or RRT for example.

Dave.

[Derek996]

This chart might help you. Top gear internal ratio on all boxes is 1:1.

[watts]

Hello

Thank you to both of you.

Matthew

[scifi]

Interesting fact...  If you add the number of teeth together of a matching pair of gears you will get 43.    So if you have a drawer full of old cogs, and you find a 20t cog, you need a 23t to match it.