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DPDT automotive, Do they exist?

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#1

I am trying to switching both the ground and hot on a skid steer attachment motor(12 vDC) to change direction of rotation. Joystick has two buttons to turn CCW and one for CW to move chute on snowblower. Each button actuates a relay running power out to attachment on a single wire. I believe(?) I need two DPDT relays mounted ON the attachment to take these two outputs and run motor in either direction to accomplish task.

It seems the easy way to do this is with a pair of DPDT automotive relays. Can’t seem to find that flavor . . .?

It appears SPDT relays are easily available, but DPDT are "UN"obtainables? Why or am I just a confused Mech. Engineer?!

#2

We do offer a few DPDT automotive relays. Link to the parts Digi-Key offers.

#3

Thanks Becky,
Those are for mounting / soldering onto a PC board.

unfortunately I need a different type— exterior weatherproof. . . flange mount would be best. . . even a simple clear plastic cover with 1/4” spade lugs would work. I have not found much available. . . it seems the market for automotive weatherproof is limited to SPST and SPDT for some weird reason!

This is for reversing a DC motor’s lead wires to change rotation direction on an attachment for a skid steer. Seems like a simple thing but . . .UNobtainable!

Brian

#4

What’s the current draw of the motor in question? That’s an item of some importance…

I’d guess that the relative scarcity of DPDT relays with ratings suitable for automotive use could be chalked up mostly to the limited call for such; there’s just not that many applications where it’s a needful function.

Environmentally-sealed relays are also less common, because not being able to vent the crud produced as result of contact wear & arcing shortens the life of the relay and increases the chance of failure. Having both supply and ground inside the same box would increase the amount of Ugly released in the event of failure, so a relay that would meet all your criteria is probably going to be a rare item.

That said, the T92P11D24-12 might be an option worth looking into. Locating it under cover somewhere to guard against direct exposure would probably be a good idea; not only for benefit of the relay itself, but also for the lead wires and QC terminal connections. Stranded wire can act like a wick for moisture–I’ve seen wires rotted a foot into the insulation before… If you really wanted to do things The Right Way, I’d put the electricals inside a proper enclosure with cable glands and such.

#5

Thanks Rick,
current draw is not really explicitly known. John Deere has these actuator’s made to their own secret OEM specs and the motors are painted over flat black so as to make identification. . . hard. However, by doing some size comparisons of similar products on line I figure that both units are not likely above 10 amps and more likely to be < 5 amp draw each. So, that big honking P &B relay should do the trick. This will see very light duty— only occasional switch a snow blower chute, only in worst winter storms used.

Your point about keeping wires under wraps etc. is one well taken. A few days ago I had to rework a trailer harness that had been exposed and the copper strands were all black from oxidation.

Thanks for the insight and time you have spent.

Regards,

Brian Schreiber
Elk River,Mn

PS When I called the OEM manufacturer(Thomson?) the application engineer actually refused to give me ANY specs after I read off the painted over model number. It’s ID told him they made it only for JD and he was not authorized to give any details out. . . even to JD customers. He was a real . . . jerk. I could hardly believe it.

#6

Hi Brian,

You could perhaps check offerings on eBay.
Like:

Cheers,
Heke

#7

thanks!

Brian

#8

Hi Brian,

It may be that you could implement the system by using SPDT relays instead of DPDT relays. Would the blueprint below be close to what you are aiming to?

motor_ctrl

Cheers,
heke

#9

Man that is GREAT! I knew a sparky would be able to figure out a way I simply could not “see”.
Very clean solution.
Thanks a lot for your time. I really appreciate the drawing.

Regards,

Brian
Elk River, Mn

#10

H Brian,

Glad to hear.
Happy tinkering!

Cheers,
heke

#11

Hey Here,
it appears to me that I can simply(?!) rewire the backside of the fuse box(relay access) and use the existing relays to make this work: nothing to buy!

wires labelled CW & CCW are “signal” feeds from joystick buttons.

rewire relays.pdf (138 KB)

#12

Well, it was a good idea–just rewiring my existing relays-- but impossible to access the backside of fuse box! So, I will be going with the design you offered as is. . . thanks again.

Brian

#13

Hi Brian,

Your rewiring plan looked solid. Unfortunate that the target equipment is not service friendly (perhaps brand related).

Cheers,
heke

#14

thanks again for the validation.
Brian