Powering electric brakes on a trailer when using a tractor

gordon21 · Mar 8, 2008

In about 2 weeks from now I have the need to back a fully loaded 16' trailer down a 80' long hill with my 4WD JD 790. The fully loaded trailer will weigh about 5-6,000# and the hill has crusher run on it and is about a 15 degree slope. Speed will be under 5MPH at all times. The trailer will weigh more than the tractor. This will be a one time 5 minute event, so I don't want to buy another brake controller, wiring harnesses, etc

Has anyone hooked up a temporary 12v feed device to the 7 pin plug on a trailer? It would seem that all you need is a 12v power source and the ability to send 12v power to the proper pin even if if were the simple crude method of sticking a bare end live wire into the slot on the connector. Attach the ground wire and insert the 12v feed as needed to force the trailer to brake as needed.

Are the runaway brake switches resettable? I have never had one activate so I never paid much attention to their construction. If so, that would be easier. Pull the wire cable to brake and then reset quickly.

tlbuser · Mar 8, 2008

the only problem with applying 12VDC direct to the harness is controlling the amperage on the line. yes, the breakaway is resettable

RobS · Mar 8, 2008

Pick up a cheap brake controller and wire it in. That will at least give you the ability to control the brake amperage and thus the brake torque. You should be able to use the manual slide switch on the controller and not have to tie it into the brake lights or anything (of course, there are none on your tractor anyway).

drtydeed · Mar 8, 2008

You could probably accomplish the same thing with some sort of rheostat (like dimmer control for dash lights etc). You do not want full current going to the brakes.

Diamondpilot · Mar 8, 2008

I am curious at how the brakes will work in reverse???? It seems like the design of the trailer brakes are meant for forward motion.

Chris

RobS · Mar 8, 2008

Diamondpilot said:
I am curious at how the brakes will work in reverse???? It seems like the design of the trailer brakes are meant for forward motion.

Chris

Surge brakes, yes but electric trailer brakes will work in reverse. Maybe not as well, but normally you're not going as fast in reverse.

I know that if I forget to turn down the controller, backing our camper into a spot can be an intersting experience! And one time the breakaway cable got caught on something and pulled the pin. I didn't realize it, had the hardest time figuring out why the camper wouldn't move, in either direction!

gordon21 · Mar 8, 2008

Rob S: I have my controller for my F-150 which I plug in only as needed and set it on the dash when towing. If I hooked up 12v to the harness (2 wires only) then I could use the slide switch on the front. All I need to do is run 12v pos and 12v neg to the harness using crimp on fittings on the two temporary leads and put those two leads only into the harness plug. Right? One person can walk along the trailer and control it as needed.

All of this is preventative. The tractor may handle the load without brakes OK. I want a backup or safety plan before backing down the hill.

RobS · Mar 8, 2008

gordon21 said:
Rob S: I have my controller for my F-150 which I plug in only as needed and set it on the dash when towing. If I hooked up 12v to the harness (2 wires only) then I could use the slide switch on the front. All I need to do is run 12v pos and 12v neg to the harness using crimp on fittings on the two temporary leads and put those two leads only into the harness plug. Right? One person can walk along the trailer and control it as needed.

All of this is preventative. The tractor may handle the load without brakes OK. I want a backup or safety plan before backing down the hill.

I'm not absolutely sure what leads the controller will need to operate properly. You could always hook it up and test it with a voltmeter on the output side. Maybe someone else can chime in with more expertise.

Heywood Jannockitov · Mar 8, 2008

gordon21 said:
I want a backup or safety plan before backing down the hill.

Could you use your FEL and backdrag it as you back down the hill, using it like an anchor? That might be a good backup, especially if there is some dirt in the bucket for added weight. Less likely to have the whole works get away from you. Were you planning on attaching the trailer to the front or back of the tractor, assuming it is a tag-along. Your tractor brakes will work better going forward, again, assuming your BH is left on and you are using a ball on your pallet forks(?)

George2615 · Mar 8, 2008

I agree that since the trailer outweighs the tractor you should buy a cheap brake controller, mount to the tractor and wire it to the trailer so you can manually apply the braking you need to the trailer. Why take a chance of that kind of load getting away from you. Wally world has cheap controllers that will do the job.