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Brook Crompton Parkinson single phase PD90S (from the 70s) 240v 11A 2850rpm 50hz
I'm using it for polishing metal with a tapered spindle adapter and buffing wheels.

I've got 2 questions.

1. (This photo was taken with all the wiring in its original position.)
I've managed to reverse the motor rotation by swapping the two black wires that are behind the copper connector, but after a few quick trials it is constantly blowing fuses.
Can you confirm that I have changed the correct wires to reverse the rotation?

2. The capacitor starts the motor with a massive jolt which forces the buffing wheel so far onto the tapered spindle that I need large pliers to loosen the buffing wheel.
If I fitted a smaller capacitor would it start more gently or is it possible to remove the capacitor and start the motor by hand by rotating the buffing wheel?

The white arrows point to the three wires that go inside to the motor.
Single phase motor reverse rotation {filename} | ElectriciansForums.net

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UPDATE.
I just sorted the problem of blowing fuses.
I fitted new bearings to the motor a couple of days ago and noticed straight away that the motor was more stiff to turn and wouldn't turn freely if twisted by hand.
I thought that was just the bearings being a tight fit, but I slackened the 3 long bolts that hold the whole casing together by just a touch and it loosened the shaft a lot and it now can spin freely by giving it a quick twist.
It now spins for a long time after the motor is switched off which it didn't do before.
So I've tightened the 3 bolts just enough to keep the motor spinning freely.

But I still have the problem of the capacitor starting the motor with too much force.
I have a metal tapered spindle slid onto the splined end of the shaft which is a fairly tight fit.
That is then held in position by a 6mm screw to stop it rotating on the shaft.
The capacitor starts the motor so violently that the 6mm screw can't hold the tapered spindle on.

I have managed a work around just now of spinning the buffing wheel by hand as fast as I can, then switching the motor on while the wheel is already spinning.
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And the motor is now spinning in the direction I want and working fine so my original question about what wires to swap seems to be answered too.
 
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Are you sure because if that is the case it is not reversible. Many single phase motors state on the rating plate which wires to swap to reverse it.
 
It's working fine in the opposite direction

Did it jolt to start in the original direction?
Swopping the 2 wires you say you swopped won't have made any difference, they were both connected via the copper bar to Neutral and still are.
There are 3 marked with arrows, which 2 did you swop?

There ar 10 wires in total across 4 terminals
2 Capacitor
2 Capacitor
2 L+N
Leaves 4 out of the motor.

The bearings need knocking onto the motor shaft a bit more to stop the jamming.
 
But aren't you spinning it by hand to start it.
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Did it jolt to start in the original direction?
Swopping the 2 wires you say you swopped won't have made any difference, they were both connected via the copper bar to Neutral and still are.
There are 3 marked with arrows, which 2 did you swop?

There ar 10 wires in total across 4 terminals
2 Capacitor
2 Capacitor
2 L+N
Leaves 4 out of the motor.

The bearings need knocking onto the motor shaft a bit more to stop the jamming.
I can only see nine wires leaving three from the motor.
Correction I can see ten now.
 
I missed the wire at the bottom which also goes into the motor so there are 4 wires going to the motor.
I have only swapped the two wires I mentioned before, the ones connected to the copper bar and that makes it run in the opposite direction.
It always starts with a jolt in both directions.
I'm only spinning it by hand to avoid the jolt over tightening the buffing wheel or making the spindle come loose.
 
I'm counting on the terminals

Top left 3
Bottom left 4
Top right 1
Bottom right 2
Yeah I can see it now.
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You need to locate the ends of the start winding and swap them. One will be at the neutral terminal possibly marked 'S'.
 
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Will a smaller capacitor make it start more gently or is there a better way of making it gradually speed up?
I was using a bench grinder before which gradually speeds up but it didn't have enough power at 450 watts for polishing.
This motor is much more powerful at 2hp but it gets up to full speed instantly.
 
If it is correctly connected reversing it will have no effect on its performance.
 
I had to reverse the rotation to get my buffing wheel spinning in the right direction and it's working fine, but I would like it to start up gradually if possible.
Could I add a knob that adjusts the speed or similar?
I have one of those kicking about for adjusting the cooling fan speed on a car amplifier.
 
No, it spins in reverse direction by itself after I swapped those two wires.
I just double checked it with the buffing wheel off the shaft.
When I start the motor it now spins in the direction I want it to but when I bought the motor it spun the wrong way.
I've swapped those wires a few times as I blew a few fuses so tried putting it back the way it was before to see if that was the problem.
Every time I swap those wires it spins in the opposite direction.
Since I slackened the casing bolts a touch it has worked no problem in the direction I want.
 
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I hear your comment that it is starting in the correct direction, however interchanging two leads that are connected together by the copper link won't change anything, as they are both still connected to the same place electrically speaking. You might have actually altered something else too.

A smaller capacitor can reduce starting torque. If there are two in parallel, maybe disconnect one. However, this will alter voltages and currents and I can't say what will be out of spec - the capacitor voltage might be higher than intended - and can't really recommend random experiments on a forum. More conventional methods of taming a start would be an autotransformer or resistance.

Whatever method, it's important that the motor starts promptly so that the centrifugal switch cuts the start winding out of circuit within the rated operation time of the capacitors (which will fail catastrophically if lefft energised for too long).
 
Are you sure this motor has a centrifugal switch as I can't remember seeing one when I took it apart to change the bearings.
It doesn't have one of those switches that acts like brakes when the motor has been switched off.
 
It looks like a two value capacitor motor or capacitor start and capacitor run motor. Some means of switching, normally centrifugal opens to take the start winding out of circuit.
 
I thought these motors has a start and run capacitor but I've checked the website and it says some have start and run capacitors and some have capacitor start and induction run.
I can live with it the way it is just now by hand spinning the wheel just before starting.
 

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