What's new
What's new

OT Electric trailer brake operation

metlmunchr

Diamond
Joined
Jul 25, 2004
Location
Asheville NC USA
My trailer pulling experience is about 80% with air brakes and the remainder with small trailers and no brakes, so I'm about halfway in the dark on the electric brakes on my RV trailer.

I've got a Tekonsha brake controller, hooked up and adjusted per the directions. Works great going forward with nice progressive application. But no braking whatsoever if going in reverse, even by actuating the controller manually. Is this right? Or is something screwed up somewhere? My driveway has a slight grade to the street, and I can pull forward, apply the trailer brakes manually, and push in the clutch. The trailer brakes stop the forward motion, but once it stops, the truck and trailer will roll backward with the controller still applied manually. Its not something wired thru the backup light switch since I'm still in 1st gear with the clutch disengaged.

Maybe this is the way they're supposed to work, but I couldn't find any info saying that, so I figured some of you trailer pullers would know. And if that's not correct operation, any ideas of what might be wrong?

Thanks in advance.
 
Possible stupid Qs time ;)

If the trailer brakes are twin leading shoe drums, the braking effect in reverse is minimal.

Has the hitch got an override that automatically releases the braking system when pulling? - that would show it's self backwards on a slope.
 
Is this a modern gyroscope controller or an older design pendulum type. I believe the pendulum type do not work in reverse, also slope will affect them. They need to readjusted as the slope changes.
Bil lD.
 
Possible stupid Qs time ;)

If the trailer brakes are twin leading shoe drums, the braking effect in reverse is minimal.

Has the hitch got an override that automatically releases the braking system when pulling? - that would show it's self backwards on a slope.

They're drums but I don't know the details of construction.

Nothing connected to the hitch. There's a small cable you hook up along with the safety chains that will actuate the brakes via a 12V battery mounted on the trailer tongue if the trailer comes loose from the truck, but nothing else I know of.
 
I had a single axle travel trailer with a Kelsey-Hayes electric brake setup years ago. These were drum brakes, but as I recall there was a machined area on the inside of the brake drum plate, and a round electromagnet riveted to one of the shoes. When energised, the magent tried to stick to the rotating drum, and this supplied the braking force. Rolling in reverse, the rotation is the wrong direction and only serves to release the brakes. Then again, one doesn't drive very fast when backing a trailer, so this shouldn't be a problem.

Having the control actuated by the master cylinder is nice for driving, and the only time I'd use the separate trailer brake handle was to dampen the motion if the trailer started to sway, which wasn't often because the hitch had sway bars. You really don't want to be using the trailer brakes by themselves; there is a lot less braking force available than on the tow vehicle, and you'll just wear them out fast.

Dennis
 
You haven't told us what type of controller you have. If it's a Tekonsha P2, P3 or newer it should provide braking in both forward and reverse. This style controller uses a signal from the brake lights in conjunction with a built in motion detector (decelerometer) to determine when to apply the brakes. The controller has to be installed according to the instructions so it can detect deceleration. In addition if the brake lights on the trailer aren't functional there won't be a signal for the controller to act on. Also with the P2 or P3 controllers you should be able to apply the trailer brakes while it's stationary.

There's a digital readout that shows how much voltage is going to the magnets in the drums. 3 volts or more should activate the trailer brakes sufficiently for you to feel them in the tow vehicle. The voltage is adjustable with a small thumb wheel on the controller

I have a 10,000 lb. equipment trailer with 4 wheel electric brakes. They work fine in both the forward and reverse directions. Having said this I would also check the adjustment of the shoes in the drums. When going forward the primary (larger rear) shoe provides most of the stopping power. As it's applied the forward rotation of the drum acts to wrap the shoe on its mounts causeing the entire surface to contact the drum. When in reverse the secondary (smaller front) shoe provides most of the stopping power. Since it's smaller, by definition you'll have less braking power. However if the shoes are properly adjusted you'll have more than adequate stopping power in either direction.
 
Electric brakes use an arm that swings with a magnet that drags on the face inside the drum. Not where the shoes rub, but the face between the shoe contact area and the hub. The magnet is by the hub when the brakes are off, the magnet sticks to the face when energized and walks outward on the face as the drum rotates. The arm has a cam at the pivot end that spreads the shoes, the higher the voltage to the magnet the more brake action you get. When you back up the magnet wants to walk to the hub so you get no brakes. So yes you have no brakes in reverse.
 
is this a new trailer or pre owned ? All the tags with electric brakes I had worked in fwd and rev . A way to check to make sure it's not your control , is , make sure your brake away batt is fully charged and pull pin on brake away (switch attached to cable ) . Pull fwd it should grab same with rev . If not in rev. this way, then trailer brakes aren't right . I never heard of them not working in reverse otherwise the brake away would be useless should the trailer become unhitched going up hill .
 
The brake control is the Tekonsha Voyager. Went thru the drill on what they refer to as leveling the control (doesn't have anything to do with orienting the control level fore and aft) and then the setting for max braking. As I mentioned, going forward it works as near to perfect as I could ask for in progressively applying the brakes, as in you don't know the trailer is back there.

All trailer lights functioning, brake, clearance, etc.

Haven't checked the brake shoe adjustment. Bought the trailer from a friend who bought it new about 10 yrs ago. He put it under a roof at a local lake and it stayed there until I bought it, so it probably has less than 1K miles of road use. OTOH, the shoe adjustment may have never been done at the factory.
 
#7 wins the prize. Adjust the brakes and perhaps lube the actuating arm cam and shoe contact points (where the shoe edge touches the back plate with white grease). Otherwise they should work as advertised.

2more¢
 
I had a funny thing happen this summer, I was pulling my 5th wheel to Colorado I was turning in to a gas station just making the corner and had a brake lock up. I was stuck half way in the drive and half in the street and couldn't move. Others couldn't get in or out of the drive, finely I decided to drag the camper out of the way. I thought I was going to have to put it in 4x4 to move the thing. My wife noticed we had more than one wheel dragging, then I remember the brake away cable. Sure enough it was pulled. It blew over and got caught in the gap between the bed and tail gate, when I turned it pulled the pin. It was a hell of a mess for a little bit till I figured it out.
 
Electric brakes use an arm that swings with a magnet that drags on the face inside the drum. Not where the shoes rub, but the face between the shoe contact area and the hub. The magnet is by the hub when the brakes are off, the magnet sticks to the face when energized and walks outward on the face as the drum rotates. The arm has a cam at the pivot end that spreads the shoes, the higher the voltage to the magnet the more brake action you get. When you back up the magnet wants to walk to the hub so you get no brakes. So yes you have no brakes in reverse.

Thanks Moon. I found a pic online of an assembled brake with the drum removed. With that pic and your explanation I finally understand how they work and why they don't work in reverse. That they don't work in reverse doesn't make any difference to me but I wanted to make sure that there wasn't something wrong since I didn't know jack about how they should work.

I read thru probably 50 pages of stuff online about electric brakes and controllers prior to posting this thread, and never saw a word anywhere indicating anything about their operation in reverse. Seems like it would be relevant information so people would know you can't use them as a hill holder at a red light.
 
Electric brakes use an arm that swings with a magnet that drags on the face inside the drum. Not where the shoes rub, but the face between the shoe contact area and the hub. The magnet is by the hub when the brakes are off, the magnet sticks to the face when energized and walks outward on the face as the drum rotates. The arm has a cam at the pivot end that spreads the shoes, the higher the voltage to the magnet the more brake action you get. When you back up the magnet wants to walk to the hub so you get no brakes. So yes you have no brakes in reverse.


This is partially correct till you start talking about reverse . I have used and fixed many electric brake trailers in the 25 years in the excavation industry . I have not come across 1 that the brakes do not work in reverse . If that was the case , then you can take the brake away switch and battery off and throw it away . If they are not working in reverse something is wrong !! Most likely rust .

I'm not trying to argue , but the statement that they do not work in reverse defies logic .
 
This is partially correct till you start talking about reverse . I have used and fixed many electric brake trailers in the 25 years in the excavation industry . I have not come across 1 that the brakes do not work in reverse . If that was the case , then you can take the brake away switch and battery off and throw it away . If they are not working in reverse something is wrong !! Most likely rust .

I'm not trying to argue , but the statement that they do not work in reverse defies logic .

So what you are telling the world is that after 25 years you still don't know how electric trailer brakes work.
 
So what you are telling the world is that after 25 years you still don't know how electric trailer brakes work.


You know, you might be right I could be a lil rusty since I got out of that bizz . I know exactly how they work , I can put them together in my sleep . What your telling us is that if you should be towing up hill and for some odd chance that your hitch should brake,or you get a space brain moment and forget the saftey pin in the hitch that the brake away is useless altogether since the brakes totally don't work in reverse , right ? So I can throw this away and not worry about keeping the battery charged ?
49755165-7015-48F4-94EF-4C12D5D49034_zpsa2bz6lfl.jpg

And before you say thats why the safety chains , I've seen them pull out of the frames rare yes , but has happened .

FWIW, they work well enough to keep the machine , truck and trailer from rolling back when loading . Ever see the back end of the truck in the air when your on the beavertail ?
 
You know, you might be right I could be a lil rusty since I got out of that bizz . I know exactly how they work , I can put them together in my sleep . What your telling us is that if you should be towing up hill and for some odd chance that your hitch should brake,or you get a space brain moment and forget the saftey pin in the hitch that the brake away is useless altogether since the brakes totally don't work in reverse , right ? So I can throw this away and not worry about keeping the battery charged ?

You must be right. Because the government would NEVER mandate a safety feature that only works in 1% of total product failures. ;)
 
You know, you might be right I could be a lil rusty since I got out of that bizz . I know exactly how they work , I can put them together in my sleep . What your telling us is that if you should be towing up hill and for some odd chance that your hitch should brake,or you get a space brain moment and forget the saftey pin in the hitch that the brake away is useless altogether since the brakes totally don't work in reverse , right ? So I can throw this away and not worry about keeping the battery charged ?
49755165-7015-48F4-94EF-4C12D5D49034_zpsa2bz6lfl.jpg

And before you say thats why the safety chains , I've seen them pull out of the frames rare yes , but has happened .

FWIW, they work well enough to keep the machine , truck and trailer from rolling back when loading . Ever see the back end of the truck in the air when your on the beavertail ?

You are towing up a hill as your hitch breaks, the trailer has some forward momentum, the break away pin pulls out, puts all 12v from the safety battery to the brake magnets, they swing all the way out and lock the brakes. As long as the safety battery has power the brakes remain locked hill or no hill. The brakes hold while you are loading because your load pushes the trailer forward till the drive wheels are on the trailer then the brake is not needed anyway.
 
I have to agree with ihbuilder that the brakes do work in reverse. The magnet on the swing arm is centered between the shoes. It can move an equal distance in either direction. The cam at the top the swing arm is also centered between the shoes, so it spreads the shoes to contact the drum braking surface When the controller sends current to the magnets. The magnet, swing arm, and cam assembly doesn't know or care which direction the trailer is moving.

To satisfy all those that say electric brakes don't work in reverse I e mailed E Trailer and asked the question. Here's the question and the response by one of their experts:

Do Electric Trailer Brakes Work in Forward and in Reverse

Question:

I have a 4 wheel trailer with Dexter electric brakes. Are the brakes supposed to work in reverse?

Expert Reply:

Yes, electric brake assemblies will work in reverse. The brake controller in your tow vehicle would still activate in reverse as long as the brakes are applied.

The actuating arm of the Dexter assemblies part # 23-27 will apply the brakes when pushed in either direction. That means that in forward or reverse the assemblies will still apply trailer brakes.

expert reply by: Jameson C
 
You may get some brake action as the magnet arm swings towards the hub, but the magnet and arm get much more leverage as they swing out. That is why the brake assemblies are marked for left and right hand use. I repaired a trailer a while back, the complaint was very poor braking in forward and brakes locking when backing up. The problem was the axle / brake assy. was backwards. This was all nearly new Dexter brakes and axles as I remember. I turned the axle around so the brake assemblies were on the correct side, now it has brakes going forward and next to no brakes in reverse.
 








 
Back
Top