# Boat trailer brake lock-up, why did it lock?



## Joshua

I have a tandem axle boat trailer with hydraulic drum brakes on one axle.  I hooked up the trailer to my vehicle and the brakes locked up.  I pulled it a bit thinking they would release.  They did not, so I backed off the hydraulic brake line to let brake fluid out.  They where still engauged a bit but I got the boat home.  

Did my coupler fail or is there a problem with the drum brakes?  I was going to replace the hydralic coupler but could there be another problem?  

What can cause trailer brakes to lockup?  Am I missing something here?

Thanks for any info,
Josh


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## loboloco

Joshua, what type of actuator does it have?  Either the actuator is faulty or the master cylinder is probably your problem.  It could be the coupling, depending on type of actuator, but I would look first at the actuator.  Don't fool with boat trailers much, so not sure which of the myriad systems they commonly use.


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## Trakternut

If it's a newer trailer, it may have an breakaway system. You'll see a box which contains a motorcycle-type battery.  There is also a light cable which hooks to your towing vehicle. Make sure the plunger it's attached to is pushed in. How this works is, should your trailer come unhooked, the towing vehicle pulls away, pulling the little plunger out, activating the brakes, stopping the trailer.
If the  plunger is in, check the battery. If it's dead, the brakes will stay locked up.  You may need to replace that battery.
The little box with the battery and actuator will be on the trailer's tongue, fairly near to the coupler.


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## OhioTC18 RIP

Do hydraulic brakes have an electric break away feature?


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## loboloco

OhioTC18 said:


> Do hydraulic brakes have an electric break away feature?


I have seen that on GC trailers, others have a pull break away that is a lot like a parking brake on a car.   I think this may be like the more modern pneumatic trailers and the default position is brakes engaged.


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## Joshua

The coupler seems to be having problems.  I can not get the coupler off the ball on my truck now!  I am going to put on a new hydraulic coupler at $200.00 and hope the problem is solved.  The drum brakes don't look to be in bad condition.  I understand the piston in the drum can go bad too...can this cause a lockup?


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## tommu56

it might have a thing on it to set the brakes if cable is pulled 







i think the cable with the hook is the brake away and they use some sort of spring to apply pressure to master cylinder 

get the manual for the coupler and check it out 

tom


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