Tandem pins will not retract, lack of air pressure?

Have you tried holding the knob out? Some of our trailers have worn out knobs that you have to hold out to actually exhaust the air to retract them.

 

I have found that on a few trailers with troublesome air-actuated pins, that it helps to completely "air up" the trailer system [and bags] then pull the red button and immediate go back and release the pins, and if they don't all retract then, then immediately rock the trailer back and forth gently to unbind them and you should hopefully hear a "thunk" when they [all] retract.

A trailer that has been parked will probably not realease upon pushing the release button because it does not have sufficient pressure available to overcome the springs.

 

I normally just rock it a bit .. If you have to drive to get air into to system I think you have other issues I'd be scared of brakes locking up if you had to get on and off them a few times if it's so slow to air up tanks

 

I always wait until the pressure is built up on the truck.

Never have an issue when I wait.
I usually hook up hoses first then release trailer brake. Got plenty of air by the time I finish up the rest.

 

Can be a air leak, bad regulator valve, you name it.

The above advice is all I've ever had to do on the air ones, though I've had a stuck evacuation valve I had to jury rig to get the thing to release.

Yes the tandem pins have constant spring pressure out.

On old school pins if you get a broken arm you have to manually take the spring out and put it back in to move the bloody things.

 

The problem is/gets worse when the air bags drop right away.

 

Mine has the same problem sometimes.
Like others have said, air it up fully. Then pull red button and hustle back there and pull the button.

Sometimes they refuse to go in, usually under a heavy load that needs the axles to be slid a few holes. I carry 2 wheel chocks and put my 4 way lockers in and use Low or reverse only and very easy, it will force them to move or push the wheel chocks. For some reason, I find putting the chocks in front of the right front set of duals seems to work best. No idea why.

 

It's possible the pins have friction against the slider assembly. Often times driving, braking the tandems are slightly 'back' and the pins are under pressure. So what you have to do is pull the little valve button, get back in and back up to release pressure off the pins so they will retract. Then you can slide around forward or back.