How long can typical elec. trailer brakes take full 12v - Pirate4x4.Com : 4x4 and Off-Road Forum

Oil burnin' · 09-12-2007, 12:51 PM

There are times when manuevering heavy truck trailer combos that it would be nice to be able to lock the trailer brakes with a full 12V. For instance pointing up a steep hill and parking for a moment to get out to look where I'm backing up... Truck parking brakes often work very poorly in reverse so it would be nice to be able to get out and chock the wheels. Sometimes it is close to impossible to even get out of the truck because of the need to be on the brake pedal.

Anybody know how long a full 12v can be applied to the trailer brakes before they burn up?

Mechanos · 09-12-2007, 01:23 PM

I don't think electric trailer brakes offer any substaintial braking when the trailer wheels are turning backwards. When rolling forward, the magnet drags on the drum forcing the brake apply lever outward to engage the shoes. When rolling backward, the brake apply lever would be pulled inward (if it will even move that direction at all) which would tend to disengage the shoes.

Oil burnin' · 09-12-2007, 02:01 PM

Now I recall that that is the way they work - thanks.

I would still like to know how long you can lock them up without burning up the magnet goint forward....

RustoleumWhite · 09-12-2007, 03:35 PM

Can't help on the magnet thing, but for the reverse thing, I have *heard* that if you put one of the brake sets on 'backwards', you might get the braking power you want in reverse.

Sure, it would limit your forward braking a bit (say instead of 4 forward brakes, you might now have the equivalent of 3 (2 at full power, and 2 and say 1/2 power).

Just a thought, I have no idea if its a good idea or not. Although for a static load (stopped) with full power applied, I would expect that even the 'limited' braking would probably be enough to hold the trailer when combined with the truck's e/parking brake.

A call to say Dexter or something might get you the best answer on the 12V thing.

Trailer Guy · 09-13-2007, 04:54 PM

When we are testing brakes we may have a full 12volts running to them for a few hours depending on what we are doing here in the shop. I've never had a magnet die from having them hooked to a full 12volts.

They can/do work in reverse, just not as well, but it would offer some help. I mean, you aren't talking about them doing all the braking, just helping. You could set up a 12volt hot wire with a toggle switch that went to the brake wire running to the plug on the truck. You could use a diode if you were worried about back feeding the toggle when it was off.

nissancrawler · 09-14-2007, 01:10 AM

Would it hurt the controller any to do that, or should there be a diode for the controller also?

Trailer Guy · 09-14-2007, 11:34 AM

Quote:

Originally Posted by nissancrawler

Would it hurt the controller any to do that, or should there be a diode for the controller also?

The one diode would allow for two in's and only one out, so it works for both the toggle and the brake controller.

Chris · 09-14-2007, 11:36 AM

I was going to throw in, the brakes on mine work in reverse pretty well. :shrug:

09-12-2007, 12:51 PM	#1 (permalink)
Oil burnin' Registered User Join Date: Dec 2002 Member # 15784 Location: Santa Cruz , CA. Posts: 335	How long can typical elec. trailer brakes take full 12v There are times when manuevering heavy truck trailer combos that it would be nice to be able to lock the trailer brakes with a full 12V. For instance pointing up a steep hill and parking for a moment to get out to look where I'm backing up... Truck parking brakes often work very poorly in reverse so it would be nice to be able to get out and chock the wheels. Sometimes it is close to impossible to even get out of the truck because of the need to be on the brake pedal. Anybody know how long a full 12v can be applied to the trailer brakes before they burn up? __________________ Compression ignition forever.

09-12-2007, 01:23 PM	#2 (permalink)
Mechanos Pirate4x4 Addict! Join Date: Aug 2001 Member # 6704 Location: Roosterville, Missouri Posts: 6,986	I don't think electric trailer brakes offer any substaintial braking when the trailer wheels are turning backwards. When rolling forward, the magnet drags on the drum forcing the brake apply lever outward to engage the shoes. When rolling backward, the brake apply lever would be pulled inward (if it will even move that direction at all) which would tend to disengage the shoes. __________________ It's IHeavy aka TORC KC0UIC -.- -.-. ----- ..- .. -.-. Nothing is foolproof to a sufficiently talented fool. Last edited by Mechanos; 09-12-2007 at 10:37 PM.

09-12-2007, 02:01 PM	#3 (permalink)
Oil burnin' Registered User Join Date: Dec 2002 Member # 15784 Location: Santa Cruz , CA. Posts: 335	Now I recall that that is the way they work - thanks. I would still like to know how long you can lock them up without burning up the magnet goint forward.... __________________ Compression ignition forever.

09-12-2007, 03:35 PM	#4 (permalink)
RustoleumWhite Zeus of the Sluice Join Date: May 2001 Member # 4506 Location: WA Posts: 4,663	Can't help on the magnet thing, but for the reverse thing, I have heard that if you put one of the brake sets on 'backwards', you might get the braking power you want in reverse. Sure, it would limit your forward braking a bit (say instead of 4 forward brakes, you might now have the equivalent of 3 (2 at full power, and 2 and say 1/2 power). Just a thought, I have no idea if its a good idea or not. Although for a static load (stopped) with full power applied, I would expect that even the 'limited' braking would probably be enough to hold the trailer when combined with the truck's e/parking brake. A call to say Dexter or something might get you the best answer on the 12V thing. __________________ I wheel a mean jackstand

09-13-2007, 04:54 PM	#5 (permalink)
Trailer Guy Rock God Join Date: Jun 2005 Member # 49181 Location: Redding, Jefferson Posts: 2,384	When we are testing brakes we may have a full 12volts running to them for a few hours depending on what we are doing here in the shop. I've never had a magnet die from having them hooked to a full 12volts. They can/do work in reverse, just not as well, but it would offer some help. I mean, you aren't talking about them doing all the braking, just helping. You could set up a 12volt hot wire with a toggle switch that went to the brake wire running to the plug on the truck. You could use a diode if you were worried about back feeding the toggle when it was off. __________________ AJ's 4x4 (530) 227-2969 BSW Racing, CalRocs, Super Mod #12 Driver: Aaron Whitehead Spotter: Adam Kovarik Thanks to: Raceline Wheels (800)529-4335 Hutchins Auto Repair (530)221-5113 Check out PARAphernalia GEAR for 550 Paracord and items

09-14-2007, 01:10 AM	#6 (permalink)
nissancrawler Registered User Join Date: Jul 2006 Member # 76684 Location: Wichita, KS Posts: 2,919	Would it hurt the controller any to do that, or should there be a diode for the controller also? __________________ [QUOTE=nahmus;9175355]asking chit chat to stop before they are done is kinda like asking piranhas to stop after one bite.[/QUOTE]

09-14-2007, 11:36 AM	#8 (permalink)
Chris III Join Date: Oct 2000 Member # 2032 Posts: 11,063	I was going to throw in, the brakes on mine work in reverse pretty well. :shrug:

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