Trucks & Trailers - how to test trailer brakes and see if they work

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Orthunnus
01-25-2012, 10:31 AM
How can I tell if my brakes are working? Any quick tests? I heard of unhooking the harness and going slow in reverse. You trailer should lock up if the brakes work. Anything else

Thanks
steve


DoubleO7
01-25-2012, 10:35 AM
With surge brakes you would want to go in reverse quickly, with a jolt.
If you go too soft and slow, the actuator might not move at all.

Skip
01-25-2012, 11:05 AM
Just drive it for a few minutes with a few stops. If the trailer brakes are warm, they are most likely working.


rwidman
01-25-2012, 11:20 AM
Just drive it for a few minutes with a few stops. If the trailer brakes are warm, they are most likely working.
Yes. Brakes work by converting energy to heat.

Better is to buy a non-contact infared thermometer. Drive for a while, then shoot the temoerature of the hubs or better yet, the actual rotors. If they are hot, your brakes are working. If not, the brakes are not working. If the temeratures are not similar for every braking wheel, you have a problem.

Finally, you can insert the lockout pin and drive (carefully) for a few miles, then stop and measure the temperature. If they are hot, they are dragging. Don't forget to remove the lockout pin.

On some systems, it's not a pin but it's the same principle.

Thalasso
01-25-2012, 11:47 AM
How can I tell if my brakes are working? Any quick tests? I heard of unhooking the harness and going slow in reverse. You trailer should lock up if the brakes work. Anything else

Thanks
steve

What type of braking system do you have ? Disc or drum. Here is how the D.O.T insp. do it.While the trailer is hooked up to the vehicle,trip the emergency brake cable on the actuator.( It might need to have a couple bolts loosened to do this by hand). When you try to drive away the wheels should be locked up. Taking a temp. of the wheels doesn't mean they are adjusted right.Drum brakes don't work in reverse so the idea of backing quick won't work.

BDeer
01-25-2012, 03:12 PM
Drum brakes don't work in reverse so the idea of backing quick won't work.

Run that one by me again? Forgive me as i have no experience with drum brakes in a trailer surge brake application, but how or why exactly would they not work in reverse?(other than the obvious reverse lockout we just discussed disabling)

Kevin Desselle
01-25-2012, 04:38 PM
Run that one by me again? Forgive me as i have no experience with drum brakes in a trailer surge brake application, but how or why exactly would they not work in reverse?(other than the obvious reverse lockout we just discussed disabling)

Thalasso is correct. Unlike automotive drum brakes, drum brakes for trailers are (freebacking). They are designed in a way that will only let the shoe seat with the drum surface in forward motion. If you switch the right side to the left and left side to the right, you wouldn’t be able to back up and would lose all braking in forward. This is why it’s very important to make sure free backing brakes are installed on the correct sides.

Yes you can do a quick test to see if the brakes are working.
All brake couplers can be manually pumped at the coupler. If you know the brand, I can tell you exactly how.
Jack up one wheel at a time and have someone spin the tire while you pump the brake at the coupler. The tire should stop with a sudden jolt when you apply pressure and spin freely when you release.

Backing a trailer up to check the brakes won’t let you know of a problem with a sticking caliper that’s not retracting. A sticking caliper can cause the brakes to burn up. Pumping the actuator manually will also let you know if there’s a stiff pedal and holding pressure or a soft pedal that may be from a system full of air.

Thalasso
01-25-2012, 06:34 PM
Run that one by me again? Forgive me as i have no experience with drum brakes in a trailer surge brake application, but how or why exactly would they not work in reverse?(other than the obvious reverse lockout we just discussed disabling)

They just aren't designed that way. If they were you would need a lockout just like disc brakes. Ever back drum brakes up a hill ? They dont stop you.

Joe
01-25-2012, 07:22 PM
They just aren't designed that way. If they were you would need a lockout just like disc brakes. Ever back drum brakes up a hill ? They dont stop you.


How does the piston in the master cylinder know what direction you are going when its being compressed? How do the wheel cylinder know that the trailer is moving in reverse when they expand the brake pads? Why would reverse matter if the brakes aren't locked out?

It sounds like the brakes just didn't work that well.

Curmudgeon
01-25-2012, 10:42 PM
Why would reverse matter if the brakes aren't locked out?

They know and it do matter. I'm guessing you've never had surge drum brakes ... ;)


To Deny What One Does Not Know Is Risky.

Kevin Desselle
01-26-2012, 07:55 AM
How does the piston in the master cylinder know what direction you are going when its being compressed? How do the wheel cylinder know that the trailer is moving in reverse when they expand the brake pads? Why would reverse matter if the brakes aren't locked out?

It sounds like the brakes just didn't work that well.

Joe, Most trailer drum brakes are “freebacking”. This is done mechanically in the brake cluster and activated by the direction of the rotation. As you can see in the pic, there is a right and left side. Freebacking brakes have only one rod coming out of the wheel cylinder. In a reverse rotation, this design pivots the shoes so they will not make full contact with the drum surface. Freebacking drum brakes do not require a blocking solenoid.
http://i128.photobucket.com/albums/p180/sporttrail/non%20trailer%20pics/001-6.jpg

DoubleO7
01-26-2012, 08:45 AM
Technically "freebacking" drum brakes do actually move and work when you go into reverse.
But the design inside virtually renders the braking ability to nothing. There is nothing downstream of the coupler/actuator that prevents that. The brakes shoes will still move a tiny bit and make contact with the drum but they do not have the mechanical advantage that the design has when going forward.

The "freebacking" drum brake assembly has the cylinder pushing. The mechanicals then take advantage of the foward rotation of the drum and "wedges" the shoes into the drum to gain greater braking
ability.

Joe
01-26-2012, 09:08 AM
Why would reverse matter if the brakes aren't locked out?

They know and it do matter. I'm guessing you've never had surge drum brakes ... ;)


To Deny What One Does Not Know Is Risky.


I cant use those things on a salt water trailer.

Joe
01-26-2012, 09:09 AM
Technically "freebacking" drum brakes do actually move and work when you go into reverse.
But the design inside virtually renders the braking ability to nothing. There is nothing downstream of the coupler/actuator that prevents that. The brakes shoes will still move a tiny bit and make contact with the drum but they do not have the mechanical advantage that the design has when going forward.

The "freebacking" drum brake assembly has the cylinder pushing. The mechanicals then take advantage of the foward rotation of the drum and "wedges" the shoes into the drum to gain greater braking
ability.

I'd never seen the inside of one until that pic above. Makes sense now.

I was thinking it was identical to a cars drum braking system. It is not.

Orthunnus
01-26-2012, 09:51 AM
everyone thanks for the input. What I have is a realextreme trailer with kodiak ss250 disc brakes. Dual axel 10400# trailer.

I filled the master cylinder and bled the brakes with a bleeding tool.

Now I need to test them.

Steve

Thalasso
01-26-2012, 10:07 AM
everyone thanks for the input. What I have is a realextreme trailer with kodiak ss250 disc brakes. Dual axel 10400# trailer.

I filled the master cylinder and bled the brakes with a bleeding tool.

Now I need to test them.

Steve There are a few ways to check, but if you are lucky enough to get pulled over and checked, this is how they will do it. really simple. Here is how the D.O.T insp. do it.While the trailer is hooked up to the vehicle,trip the emergency brake cable on the actuator.( It might need to have a couple bolts loosened to do this by hand). When you try to drive away the wheels should be locked up.

weimdad
02-13-2012, 11:42 AM
How can I tell if my brakes are working? Any quick tests? I heard of unhooking the harness and going slow in reverse. You trailer should lock up if the brakes work. Anything else

Thanks
steve

That will work. I have to back up my drive way and have to put a steel pin in the slot to keep the acuator from activating the brakes.



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