Backing up with disc trailer brakes

[xtn]

Well, in order for the surge brakes to operate while you're backing up - regardless of the ground's slope - the tongue mechanism must get compressed. Either your braking system is faulty in some way, or the tongue mechanism isn't getting compressed, due to some combination of slope, very light acceleration, and/or friction in the tongue mechanism. Maybe the joint where it slides together needs to be lubricated?

xtn

 

[BigEddy]

Easy test.

Chock the trailer wheel and back up slightly. Have someone watch the coupler while you apply backing pressure. Does the tongue compress? It should shorten about an inch. If it does then at least the surge cylinder is moving. If it doesn't then it's seized or the backing solenoid is stuck on and you have no trailer brakes at any time.

Once you know the hitch end is working then its time to check each wheel. With a tandem I'd be tempted to remove one wheel and apply backing pressure as before then try to spin the empty hub. No pressure - spins. Apply pressure - stops. The usual test is to try to back a load up a steepish gravel hill. The trailer wheels should lock when the tongue compresses and skid.

You can sometimes use a 2x4 as a lever to apply pressure to the tongue for testing. Loop the safety chains around one end, rest on the hitch end and pull on the long end to apply or remove pressure. Jack up one side and have a bud check for braking at each wheel.

All above assumes properly installed and bled lines with a full reservoir.

 

[Coyote machine]

Easy test.

Chock the trailer wheel and back up slightly. Have someone watch the coupler while you apply backing pressure. Does the tongue compress? It should shorten about an inch. If it does then at least the surge cylinder is moving. If it doesn't then it's seized or the backing solenoid is stuck on and you have no trailer brakes at any time.

Once you know the hitch end is working then its time to check each wheel. With a tandem I'd be tempted to remove one wheel and apply backing pressure as before then try to spin the empty hub. No pressure - spins. Apply pressure - stops. The usual test is to try to back a load up a steepish gravel hill. The trailer wheels should lock when the tongue compresses and skid.

You can sometimes use a 2x4 as a lever to apply pressure to the tongue for testing. Loop the safety chains around one end, rest on the hitch end and pull on the long end to apply or remove pressure. Jack up one side and have a bud check for braking at each wheel.

All above assumes properly installed and bled lines with a full reservoir.

Sounds like a good method. I will be trying it in the next few days, weather depending...
If for some reason I forget to post back results someone please PM me to jolt the memory banks.

TX

CM