Free Backing Hydraulic Trailer Brakes Not Allow Trailer To Back Up

Updated 09/27/2011 | Published 09/26/2011

Products Featured in This Question

Dexter Galphorite Free-Backing Hydraulic Trailer Brake Assembly - 10" - Right Hand - 3,750 lbs

(53)

$91.76

Uni-Servo Wheel Cylinder for 10", 12" and 13" Dexter Brake Assemblies - Zinc - RH

(79)

$50.43

Uni-Servo Wheel Cylinder for 10", 12" and 13" Dexter Brake Assemblies - Zinc - LH

(79)

$52.84

Question:

I am not sure how to tell if I have free backing plates or not compared to the pictures you show, it looks like I do have free backing plates. Recently, I bled the brakes, adjusted the shoes up and now I cannot back up. Is there something that I am missing Thanks

asked by: Greg

Expert Reply:

Basically, a free backing brake assembly like # T4423400, will have one shoe that is shorter than the other and the bracket will be a different shape. On a regular assembly, the shoes will by mirror images of each other. Also, on a free backing assembly, you would be able to back up.

Also if the actuator has a reverse lockout on it, make sure it is engaged so you can back up. There are 2 types of lockout: manual and electric. A manual lockout will have a lever on the coupler that you have to physically push into the lockout position and it will be labeled.

An electric lockout uses a wire, attached to the reverse light circuit on the vehicle and a solenoid on the coupler, to engage the solenoid and not allow fluid to go back to the brakes when the vehicle is put in reverse.

A free backing brake will apply the brakes at first but then release as you continue to back up. If you do have free backing brakes that are not allowing you to back up, it could be a problem with the wheel cylinder, air in the lines, or the brakes may be too aggressively adjusted.

If the wheel cylinder is malfunctioning, you would need to replace it. For Titan 10 inch hydraulic brakes like what you have referenced, use # T0977700 (right hand side) or # T0977600 (left hand side).

If you suspect there is air in the lines, you will need to bleed the brakes again. I have included a link to a video showing the brake bleeding process our installers follow.

If the brakes are adjusted too tight, it could cause the problem. You would either need to apply more force to get the free backing brakes to disengage, or re-adjust the brakes. When you are adjusting the brakes, you want to be able to spin the wheel (with the brakes NOT engaged) and you should be able to hear the pad drag a little on the inside of the drum.

I have included a link to another video showing our installer adjusting some brakes. It is near the end of the video around the 4:54 mark.