DC Motor problem Part 2

[lumphammer]

OK I've replaced the dodgy carbon brush in the motor, full of anticipation I connected up to 12V - Nothing happened except the wires started getting hot and smoke started coming out of the connection block. Ouch.
So I disassembled the gear box to find 3 slip rings and a rather complicated commutator.
Something is going on inside the connection box, but I can't see how to into it, but it looks like I might have have to drill out the rivet on the right of the connector.
Any thoughts of is going on?
The motor is connected via a lever arm directly to the diaphragm of a Mk5 Universal pump

 

[William_H]

It is a bit hard to figure out what the 3 things are in the last photo. Did the motor only have one brush? Usually 2 for a commutator type motor. But then you mention slip rings which might imply a brushless motor. Or perhaps you have the wrong name for the "slip rings".
Commutator has many segments of copper each insulated from one another. So the brushes contact different segments of the commutator as it rotates. Often looks burnt and dirty can be cleaned with fine emery paper.
Now hot wiring no rotation might imply a short circuit in the wiring or might mean motor is seized. Not rotating so drawing high current. Ppologies if you know all this. Need more description or photos. ol'will

 

[VicS]

It is a bit hard to figure out what the 3 things are in the last photo. Did the motor only have one brush? Usually 2 for a commutator type motor. But then you mention slip rings which might imply a brushless motor. Or perhaps you have the wrong name for the "slip rings".
Commutator has many segments of copper each insulated from one another. So the brushes contact different segments of the commutator as it rotates. Often looks burnt and dirty can be cleaned with fine emery paper.
Now hot wiring no rotation might imply a short circuit in the wiring or might mean motor is seized. Not rotating so drawing high current. Ppologies if you know all this. Need more description or photos. ol'will

I think you need to read lumphammer's post together with his original thread on the same subject.
DC motor question

 

[ean_p]

Is it by any chance that the assembly is a re tasked windscreen wiper assembly that incorporates a park facility.......

Looking further it appears that it is a re tasked wiper motor and the 3rd brush is part of a two speed control . Which if it is the case will mean there are also other components involved such a zener diodes etc......that being the case then your problem may simply be that one of these components has become defective.
Have a look here Wiper Motor Guide in 2020 - Learn Everything About Wiper Motors.

and for info the diagram here...... US4843286A - Vehicle window wiper with three brush motor and speed limiting - Google Patents

 

[Alex_Blackwood]

OK I've replaced the dodgy carbon brush in the motor, full of anticipation I connected up to 12V - Nothing happened except the wires started getting hot and smoke started coming out of the connection block. Ouch.
So I disassembled the gear box to find 3 slip rings and a rather complicated commutator.
Something is going on inside the connection box, but I can't see how to into it, but it looks like I might have have to drill out the rivet on the right of the connector.
Any thoughts of is going on?
The motor is connected via a lever arm directly to the diaphragm of a Mk5 Universal pump

Sorry, but impossible to tell from pics. I would have to see the beast. Any other comment would be pure guesswork and speculation. Have you got an Auto Electrical company in the area that you could contact for advice?

 

[rogerthebodger]

Is it by any chance that the assembly is a re tasked windscreen wiper assembly that incorporates a park facility.......

Looking further it appears that it is a re tasked wiper motor and the 3rd brush is part of a two speed control . Which if it is the case will mean there are also other components involved such a zener diodes etc......that being the case then your problem may simply be that one of these components has become defective.
Have a look here Wiper Motor Guide in 2020 - Learn Everything About Wiper Motors.

and for info the diagram here...... US4843286A - Vehicle window wiper with three brush motor and speed limiting - Google Patents

That was my thinking as I have used wiper motors to power valve actuators and had to remove the parking switches but mine could rotate in for and aft direction

https://flic.kr/p/Wop89u

https://flic.kr/p/WYQwRk

 

[ean_p]

That was my thinking as I have used wiper motors to power valve actuators and had to remove the parking switches but mine could rotate in for and aft direction

https://flic.kr/p/Wop89u

https://flic.kr/p/WYQwRk

When you say 'could' rotate back and forth Roger how in practice was that achieved....the old style wiper motors generally just drove a cranck which I believed translated to the wipe stroke.....or in the above the pump stroke.....

 

[Alex_Blackwood]

Even if a re-tasked wiper motor it has previously been running in that application so will have already had any Mods carried out. No?

 

[rogerthebodger]

When you say 'could' rotate back and forth Roger how in practice was that achieved....the old style wiper motors generally just drove a crank which I believed translated to the wipe stroke.....or in the above the pump stroke.....

Wiper motors cone in several types but most have a worm on the end of the motor shaft that drive a worm wheel that has a crank that moves the wiper in a too and forth motion which is the same as the henderson MkV pump input

This crank can be internal of external mine are external and so I remove the crank and flt a small gear as below to increase the torque and slow the speed

If the crank in internal you just strip it down and fit the gear on to the inside worm wheel

https://flic.kr/p/VKkRPn

To reverse the direction of the motor I just reverse the plus and negative as as most small wiper motors are permanent magnets that will reverse the direction.

If the motor has a field coil you just reeras the + and - on the field coil but not on the commutator.

My stop solenoid is also a wiper motor with a different limit swatch set up to change the motor from stopt to run position with the turn of the "ingestion switch

 

[ean_p]

Even if a re-tasked wiper motor it has previously been running in that application so will have already had any Mods carried out. No?

Yes it would Alex, but it possibly means that it's not a straightforward motor especially if it had a parking and two speed circuit fitted . Therefore possibly a latent component may have failed / gone oc which may impact on its function . Have a look at the US patent diagram for a few possible causes.......

 

[ean_p]

Wiper motors cone in several types but most have a worm on the end of the motor shaft that drive a worm wheel that has a crank that moves the wiper in a too and forth motion which is the same as the henderson MkV pump input

This crank can be internal of external mine are external and so I remove the crank and flt a small gear as below to increase the torque and slow the speed

If the crank in internal you just strip it down and fit the gear on to the inside worm wheel

https://flic.kr/p/VKkRPn

To reverse the direction of the motor I just reverse the plus and negative as as most small wiper motors are permanent magnets that will reverse the direction.

If the motor has a field coil you just reeras the + and - on the field coil but not on the commutator.

My stop solenoid is also a wiper motor with a different limit swatch set up to change the motor from stopt to run position with the turn of the "ingestion switch

Ah so you mean the 'crank ' action generated a reciprocal motion.......I thought you meant that you motor revolved clockwise and anticlockwise

 

[rogerthebodger]

Ah so you mean the 'crank ' action generated a reciprocal motion.......I thought you meant that you motor revolved clockwise and anticlockwise

Well it depends on the application.

On the one shown the motor does rotate clockwise and anti that will move the crank through 90 degrees to turn the ball valve,

he OPs application could be done that way but if simpler to make the trough of the crank the same as the pump for and aft movement then you do not need any limit switches and control relays

I have also used the same type of motor to make screw actuators as hatch openers again with clock . anticlock drive and limit switches to control the open and closed position

I have also used 12 Vdc battery drills as a motor gearbox or hydraulics for heavy hatches

 

[lumphammer]

Thanks for the replies everyone , On opening up the connection box the wiper arms are just connected to unused terminals, and are not doing anything as far as I can see, so I suspect the suggestion of it being a re-tasked windscreen wiper motor and gearbox is likely correct.
Once inside the connection box the problem was obvious and turned out to be a short circuit due to insulation failure. I fixed that and my loo is now back in order