• A Plus Truck Repair

28" Haulmark Cargo Trailer Electric Brakes Repair

Updated: Jul 3

I had a emergency repair road call recently from a guy who owned one of this 2-axle Cargo Trailers with electric brakes. His complaint was "dragging brakes on driver side", also he said that it almost felt like something broke inside the brake, separated and was making a rattling noise. I have started from from the axle the driver pointed me out to, but after taking the wheels off of both axles on driver side could not find anything suspicious. Everything looked normal. After verifying all was operational (I had the driver to hook the trailer up to the truck and had him apply the brakes several times while wheels being in the air off the ground about 2-3" and I was spinning them one at a time until complete stop when brakes were applied several times) I have moved to the passenger side axle to make sure everything looks OK there also. Despite that side not being a driver's primary concern I still decided to check it out, since that what mechanics customarily do: they listen to the customer's concern, but also create their own "picture" of potential problem by verifying the customer's concern. After taking off both wheels from passenger's side axles I have found the culprit: the front axle of passenger's side of trailer had the self adjusting mechanism fallen apart and rattling inside the drum while trailer was in motion thus creating a sound driver was concerned about. I have also noticed that none of the wheel hubs had inspection slot covers behind the wheel hub. I concluded that since the driver goes all over the US with this trailer he might of gotten some water inside the wheel, which corroded the self adjusting mechanism's spring, which eventually rusted out and snapped and got loose the mechanism which ultimately led to ruining of the brake drum, shoes and created a customer to call us for a repair. Picture below shows the broken brakes self adjusting mechanism. Also, to properly preload the wheel bearings I have first tightened the axle nut to about 20 Ft lb and then turned the brake drum about 10 times in each direction (10 times clockwise and 10 times anticlockwise). After that I have loosened the axle nut completely and just hand tightened it before setting the locking washer in. I also made sure none of the bearings were overheated and were functional. After reassembly I have repeated the procedure of checking out the brake's functionality same way I have done for the driver side axles. All in all the repair was completed successfully and customer was very satisfied with it. I am sure he is going to have a lot of trouble free miles with his Haulmark Cargo Trailer. At a bare minimum I am sure there will not be any worries about his brakes functionality for a long time. Also, our tech ordered and installed all 8 slot plugs ( 2 per wheel hub shield) just to make sure that road dust, debris and rain water will be kept outside. Happy Cargo Load Moving guys!

Electric brake solenoid, engaging the brake shoes operation during braking.

Damaged Brake Shoe at passenger side axle caused by ruined brake self adjusting mechanism

This spring was broken on the other side of the axle, causing a rattling noise

Culprit of a problem: broken pieces of self adjusting mechanism, causing brakes to drag

TAGS: repair, repair truck, semi truck repair, sacramento truck repair, help onroad.


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