Axminster lathe part identification

[PalletPaul]

What name would you call this?

It's for the speed control and works out the speed for the display

 

[Dominik Pierog]

RPM meter or inverter?

 

[PalletPaul]

Its for RPM's.

It's attached to the headstock spindle and then when spinning passes between a black plastic piece on the back of the display... and thus calculates the RPM's

 

[Dominik Pierog]

Its rpm meter its could be optic or magnetic.

 

[Lazurus]

Never found the need for one myself

 

[Paul Hannaby]

Would that be a tachometer?
I think the bit you are talking about is a rotary vane that passes through the sensor - which is either optical (beam of light) or magnetic (inductive sensor)

 

[Duncan A]

The pickup (optical, or a magnetic proximity sensor) produces pulses as the rotor passes it. The pulses are counted by the electronics and a number is output to a (usually) digital display. Dominik's post shows this