55 Michigan loader brake system

[Caseybow123]

Started up the Michigan 55 loader yesterday to start stacking logs for the mill. Unfortunately,  front brakes are locked up and will not release. Anyone have experience with the air brake system on these machines. All I know about them is that they work great when they work, but no experience at all when they fail. 
I was tapping the brake pedal to hopefully get air to the front so they would release, as I have done this many times before. It however didn't work this time. I stepped on the pedal a little harder and a rush of air could be heard leaking out by my foot. The pedal then went soft. It did harden up again and air pressure guage was reading 120 , but front still locked. I am thinking possibly I need a new foot pedal air valve(Treadle valve). Does this sound like a fair assumption?

[mudfarmer]

No experience with it but had a minute and found this link with a bunch of info that might help?? (might not!) michigan 55b Brake problems | Heavy Equipment Forums

[Caseybow123]

Thanks Farmer, I have read this post already. Ontario Al informed me about it.

[C5C Tree Farmer]

Check to see if the quick release valve for the front axle is operational. Sometimes they corrode shut. This is the small "T" valve used where the feed line branches into the two lines that go to each of the wheels.

[Caseybow123]

Thank you Treefarmer,
 I will add this to the list. When it warms up some here in Saskatchewan I will be doing a variety of tests on it to hopefully find the problem.  I am very uneducated in air brake technology, although it seems to be a fairly straight forward system. I only wish my shop door opening was a couple inches higher so I could get it into a heated shop. A couple days in a warm environment may correct all my issues. Until it warms up though I am trying to gain as much info and experience I can.
Cheers.

[GRANITEstateMP]

Caseybow123,

We just had a similar shop door problem with a silage truck needing head work. We let a lot of air out of the tires, got it inside, aired them up again. Inside is a happy place for broken equipment

[Caseybow123]

Was going to try dumping air from tires, but after measuring still too high to clear door.

Caseybow123,

We just had a similar shop door problem with a silage truck needing head work. We let a lot of air out of the tires, got it inside, aired them up again. Inside is a happy place for broken equipment

[OntarioAl]

Tarp in all 
Put a set up a torpedo heater blowing in
Wait for a relatively mild day and fire up the heater
Cheers
Al

[Caseybow123]

I had a chance to go underneath the loader this morning.  When I started the loader and air pressure builds, you can watch the small pushrod come out of the air chamber, which in turn squeezes calipers to apply brakes. I disconnected the air supply to the front tank and the front brakes released. After capping off the lines to use loader with no brakes(flat ground only), I found that the declutch pedal still works. I would assume then my problem would be either a stuck treadle valvein the brake applied position or a non- functioning ERQ valve. Does this sound like I am on the right track?

[C5C Tree Farmer]

The treadle valve is in the apply position. Under the pedal is a roller that pushes on a steel cap which activates the air valve. Sometimes the steel cap corrodes in the bore and sticks in the applied position. Another scenario I've seen is that the pedal hinge gets corroded and the return spring in the treadle valve can't push the pedal back up. Try spraying the area with penetrant and verify that the cap is moving up and down freely and the pedal comes back up into the release position.