winch wiring challenge:

[dumbdunce]

I have an old ramsey REP8000 which I blew up the motor of. I have a 12v truck starter motor. I have almost finished grafting the 2 together mechanically. I don't want to get involved in current, duty cycle, power etc discussions. this motor will do the job adequately.

problem: the REP8000 had a permanent magnet motor and as such the control box has only 2 solenoids. the truck starter is series wound. I don't want to buy more solenoids. Assume I have modified the starter motor to run both directions, and all I need to do is reverse the polarity of the field winding relative to the rotor winding using just two single pole, single throw solenoids. I am pretty sure it can be done, just having trouble getting my head around it.

[chimpboy]

problem: the REP8000 had a permanent magnet motor and as such the control box has only 2 solenoids. the truck starter is series wound. I don't want to buy more solenoids. Assume I have modified the starter motor to run both directions, and all I need to do is reverse the polarity of the field winding relative to the rotor winding using just two single pole, single throw solenoids. I am pretty sure it can be done, just having trouble getting my head around it.

Not being completely familiar with winches, I am struggling to see how the original DC motor would have run in two directions from two single-pole, single-throw solenoids.

I would have expected it to be two single-pole, DOUBLE-throw solenoids. These would both connect both terminals of the winch motor to GROUND when nothing is switched on, then throw over to +12V on one solenoid or the other depending on which direction you wanted to go in.

You have four possible states:

1. Both solenoids unenergised - both terminals negative/ground.
2. Solenoid A energised (only) - terminal A +ve, terminal B -ve. (forward)
3. Solenoid B energised (only) - terminal A -ve, terminal B +ve. (reverse)
4. Both solenoids energised - both terminals +ve (this means the switch is fucked, but it is worth noting that it doesn't cause a short which means it's a good design - bad switch does not equal big fire).

AFAIK that is the simplest set-up possible for reversing polarity with heavy current and without seeing it it is what I'd expect for a winch.

Are you sure that the existing solenoids are only single throw?

I have an old ramsey REP8000 which I blew up the motor of. I have a 12v truck starter motor. I have almost finished grafting the 2 together mechanically. I don't want to get involved in current, duty cycle, power etc discussions. this motor will do the job adequately.

For what it's worth, I agree that this type of motor should be more than adequate for winching and probably superior to what was there before. (And since you asked, my old man agrees...)

Jason

[dumbdunce]

damn you're right, I should have looked in the box of bits before I posted!

the solenoids are double pole with 4 fat terminals - each has an electrically isolated NO and NC circuit. I now have a scribble of what I believe is workable circuit diagram for running a series wound motor, with similar safety ie both solenoids on = 12v to nowhere, both solenoids off = 12v to both sides of the commutator, it could be flipped to swap the position of the commutator and the field winding but this is the easiest way to make the physical modifications to the motor.

do you see any potential problems with it? it is essentially the way warn winches are wired, except they use 4 fully independent relays to do the switching.

[chimpboy]

I think this would work but I am not sure it's good to have the terminals on the rotor at +12V when everything is meant to be switched off.

I *think* the attached also works but leaves all the terminals cold.

Sorry it's messy but basically each of your solenoids is switching one rotor terminal between the field coil and +12V.

So when you activate one solenoid it sends +ve to one rotor terminal. The solenoid that isn't tripped leaves the OTHER rotor terminal connected to the field coil and you have a circuit.

Check it!

Edit... - it's really the same as your diagram except that instead of having +12V on the NC part of the solenoid I've put the field coil there... and swapped the +12V to the NO.

Jason

[dumbdunce]

yep that works, except after having some more looks at the commutator head, I have decided to modify the field winding/motor body for two terminals on the body because 2 of the commutator terminals are fairly irrevocably earthed. it just means swapping the positions of the field and rotor in either diagram; operationally it is the same.

thanks for your help.

[andy & di]

I am so glad you bloks know what yer on about !!!!!!!!!!!!!!!!!!!!!!

Did it work?

[dumbdunce]

I am so glad you bloks know what yer on about !!!!!!!!!!!!!!!!!!!!!!

Did it work?

yes it does. want to buy a winch?