Trailer brakes not working

Ok, so in my case it sounds like the check valve may be stuck open. I don’t hear any leaks but the tank needs to fill every time.

 

If your mechanically minded get a 3/4 af spanner take your maxi's off chock up your wheels get under the back axles of your trailer and you'll see on the rocker arms an adjuster wind it back a touch then tighten it right up and wind it back a half turn this adjusts your brake tension also while under there check for brake pad wear.

 

If it sticks wide open, you'll know it, it'll dump all air out of the tanks when you pull the red know out and they'll take long to set. Typically when they go bad, they just fail to seat. Set the brakes and then remove the red gladhand, put your thumb over it for 30 seconds or so to see if it's leaking back into the air line slowly. If it's not leaking into the red line, your leak is elsewhere.

I'm not sure what kind of valve you have. Sealco valves are common and you can buy a cartridge for them that usually fixes them right up in 10-15 minutes. No need to remove the valve. Bendix SR5 valves are also common and I just replace them. New ones are about $70.

 

I’ll have to see which I have and fix it. Occasionally, I have to drop my trailer and let a yard jockey pull it. Those guys are notoriously impatient when it comes to waiting for brakes to release. It’s not their $3500 worth of tires they’re flat spotting.

 

Mr @GrapeApe is it possible the check valve can fail in a way that can cause the spring brakes to not release?

 

Not that I have ever run into, but I can't say that it's impossible, just unlikely. That looks to be a Sealco 110500 valve. That has what they call spring brake priority, meaning that it won't fill the tanks at all until the chambers have enough pressure to release the spring brakes.

If your spring brakes are not releasing, it's a fairly simple diagnosis. The spring brake release valve is the only thing between the red supply line and the spring side of the chambers. Check air at each point until you find where it's not coming through. It could be a blockage inside the valve.

Here's some info from Sealco that might help you diagnosis:

A basics on how they work:
Sealco Commercial Vehicle Products - Spring Brake Valves

Some troubleshooting:
Sealco Commercial Vehicle Products - Troubleshooting

The troubleshooter isn't very good, but does cover common problems.

 

Thanks sir . I made a little YouTube video on how to change it.

 

I love this, it's the reason I come here to try and help. You saved at least $100, probably more, doing that yourself and took the time to record it to help others. Well done sir!

 

Ok so my trail brakes are not releasing When I push down it won’t stay but it’s getting air to the trail Any suggestions on what the problem could be