New motor for wabeco lathe

Hi, the control board on my Wabeco d3000 lathe has gone bad. Wabeco no longer carry parts for the lathe so I am at a bit of a loss what to do. The motor is rated at 1.4kw but that’s the only information they give. I take it that it’s dc motor but can’t be sure. There is no label on the motor itself. So my question is would the motor be dc ? Is there a control unit I can buy to bypass the old board. Or is there a motor upgrade that would suit. Thanks. Michael

I expect so. Change it for a 3 phase motor with VFD. A far better system.

Does it have brushes? If so it's a dv commutator motor. Several companies supply industrial drives suitable, Google KBE. But the motor might be a bit elderly and the brushes needing replacing anyway in which case a 3 phase motor and VFD upgrade would be a good approach.

Thanks chaps

Here's the circuit diagram from the manual:

Assuming the problem isn't confirmed by magic smoke from a cooked control board!

The manual says the brushes should be sanded down every 100 hours and the commutator cleaned. Plus advice to check in the event of a stoppage that the plugs and sockets haven't vibrated loose. If that's been done, I'd check the usual other mini-lathe weak-spots before rushing to change the motor or board:

1. Check the safety cut-outs are all allowing power to reach the board:
   • S10 - switch on chuck guard closed
   • T2 - thermistor on motor closed
   • S1 - Emergency cut-off reset, not popped open
2. Confirm the speed control potentiometer is working - they often fail by going open circuit. A squirt of switch cleaner might get it going, or replace

The manual says the motor is single-phase, and the circuit shows 8 connections:

• Pair to Thermistor, disconnecting the mains if the motor gets too hot.
• Pair from Tachometer to board providing speed regulation. If this failed would the motor run fast, slow or not at all?
• Pair to K1 and K2. I guess these are the field winding and may be fused. If fused, this pair may be the main power input. Check for fuses - I don't recognise the circuit symbol, but it could be an inline fuse. I can't see anything else that might be a fuse,
• Pair to W1 and W2. I guess these feed the armature and are fed a control voltage from the power board.

The claim to be a single-phase motor might make sense if this was a simple triac triggered speed control circuit, but I don't understand what the brushes are for. They suggest a DC motor, or is there a type of AC motor with brushes?

Dave

A motor with brushes, a commutator (segmented rotor contacts) and a wound stator (not permanent magnet) will run on AC or DC. For this reason they are often called a "universal" motor.
I've run a 110V drill off a couple of 24 volt batteries in the past when no other power was available. Might not work with a variable speed one.

Robert G8RPI.

Edited By Robert Atkinson 2 on 13/07/2022 19:27:20

Doh, is it that simple? In my defence, the spec says it's a 1.4kW motor, which I assumed is too big to be a Universal. Don't know why though, except I've only come across Universals on sewing machines and small power tools up to about 250W max.

Dave

The two "W" connections are more likely to be the windings and the "K" connections brushes as Kohlenstoff is German for Carbon

Universal motors appear on angle grinders, vacuum cleaners, SDS drills and jack hammer things, I'm sure I have seen some rated well over 1kW.

Ian P

Almost certainly a wound field DC motor, commonly used for larger sizes rather than permanent magnet field. Many controllers have an output to drive the field winding. A series wound motor is very unlikely in a lathe because it's speed torque curve is very unfavourable.

Thanks again.