That made me re-coil in horror
12v solenoid
- Thread starter andyandy2
- Start date
That made me re-coil in horror
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Thanks for all the replies, have just bought a roll of wire from maplins, so will have a go as soon as i get chance (nothing to lose really) Space Cat mentions a special technique for winding, is this very important ? is it to do with current flow, or heat disipation through the coil ? Am i right in thinking that one end of the coil winding goes to earth through the metal case ? Finally the old coil was covered in a sort of rubberised plastic (poor description) is this just for insulation or a sort of heat sink? Thanks
If you mean the technique of winding yourself towards an anchorage point, that's not important. It's just easier that way. Trying to do it with the coil in one hand and a loose wire in the other is a mugs game.
What is important is to get the turns lying evenly in layers. If you wind them on at random you'll end up with insufficient turns. You might get the same number of amp turns because the resistance will be lower but you'll have more heat.
That bit about jumping grooves isn't a trick but a necessity. Wires in alternate layers cannot lie entirely within the grooves formed by the wires below. You'll see this when you try it.
If you have only one wire on the old coil then this is likely. It's common practice in automotive electrics to use the chassis as a connection. You can find out for sure by unwinding the old coil. If the other end is connected to the bobbin it will simplify the job because you'll have an anchor point for the start of your first layer.
It's for insulation and mechanical protection. It could never be a heat sink. On the contrary, it will tend to trap heat - so don't overdo it!
This is when re-winding a coil gets annoying..... You strip off miles of perfectly good wire just to find the fault was the earth connection under the windings has come loose
more likely just a bit of heatshrink tubing just to hold everything together.
Space cat - That should be Ampere turns, not Amps per turn shouldn't it?
(magnetic field is proportional to the current multiplied by the number of turns)
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The solenoid is off a 1983 tractor, there are no electronics just a 12v supply from a rocker switch on the dash it operates the "dual power" a means of doubling the amout of gears, the worst that can happen if it fails is that the tractor changes down 1 gear, so i think its worth a try especially if i can save £300+
Given it's function, I would take a guess it's probably very similar, if not identical to the solenoids that operated borg warner and similar overdrive units on cars of that era. They had a solenoid about the size of a soup tin sticking out the side of the transmission. It certainly sounds like it is doing the same job as an overdrive unit, so maybe a car scrapyard could yield a solenoid.
Some commercial vehicles have a 2-speed axle controlled by a similar solenoid too.
Some commercial vehicles have a 2-speed axle controlled by a similar solenoid too.
Thanks for the suggestion Tickly T, i've seen the sort of solenoids you mention, but they are much to big, this one is about the size of a standard cotton reel, it fits in an internal position in the bellhousing
In that case wouldnt any heavy duty solenoid off the shelf do?
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