Lil' baby Herbert drill (Again)

[Maker]

That's the speeds plate on my little Herbert drill, It has a two step pulley on the spindle for the two ranges but I can't tell what on earth A, B and C refer to. Any ideas?

I asked a couple of years ago when I got the drill but no one knew.


On the right is the quill pulley, its 3/4" on top and 1" on the bottom, there's also the 2" collar on the left that can be attached over the normal pulley, but I'm not convinced it's original to the drill. The motor pulley is missing but appears in the diagram above to not be stepped.

I could definitely make a set of stepped pulleys to fit it (And I may well do) but I still want to know how it should work.

So, what are A, B and C?

There's no gearbox. I don't think it's a 3 speed motor but I'm about to go make sure. I'm pretty sure it's older than VFDs have been commonplace so I don't think it's missing some kind of electrical controller.

 

[Barking Mat]

I can only guess its a three speed motor?
What electrics have you got going to the motor?
Is the motor original?
What switched have you got?
Sweet little machine.

 

[Barking Mat]

What's that on on the bottom rhs?

 

[Maker]

It's the original single speed motor, the electrics are three phase from an inverter and the original switch is triple pole single throw, so is only to turn three phase power on and off.

All good suggestions but I think I might have figured it out...

A, B and C could be 3 pulleys of different sizes you can fit on the motor?

My thinking behind it is; The bolt that holds the pulley to the shaft has LH stamped on it, and the belt guard very helpfully tells you the thread is left hand;

Now it could just be that it was designed by a really helpful person who wanted to make sure no one ever struggled to get the pulley off should it need to come off, or it's because the bolt is designed to be removed in the regular operation of the machine.

This may also explain why the original pulley(s) are missing, as they're made to be removed and they were lost.

If A is 4.5", B is 2.25" and C is 1", they would give approximately the speeds listed. I think this setup might require 2 or 3 different belts though, I need to measure how far the motor can be moved for tensioning the belt.

Sounds plausible doesn't it?

What's that on on the bottom rhs?

Where are you looking, which picture?

 

[Barking Mat]

Post #1, 3rd picture, its probably the on off switch.
Just looks like s three speed motor and two different belt positions giving 6 speeds to me.
But I could be wrong....

 

[Keith 66]

I have seen a similar drill, it had three stepped pulleys under the top cover with two vee belts. The centre pulley is an idler mounted on a swinging arm. Single speed motor, 2x3 = 6 speeds.