BR400 Brakes

[cbender]

We have a 1994 BR400+ with about 5000 hours. Last season, I had a couple of incidences where the brakes would not release. A simple cycling forward/reverse may have been the fix then, but during this fall's summer service, I could not get the brakes to release.

I am currently trying to look at a weak brake solenoid and will soon be able to test for charge pressure at the solenoid. Does anyone have any other ideas if it ends up not being one of these? No apparent leaks related to this problem.

[Power Giant]

Call the dealership. LOL

[cbender]

Call the dealership. LOL

Thanks, I just did that yesterday.

[midwestsnopro]

check the charge pressure on your drive pump. If you look by the hydro filters located on the pumps, one of them will have a small hose going back to the brake valve. Check the pump with that hose attached to it. The brakes are released by the charge pressure of that pump and if the charge pressure drops, usually while under more of a load the brakes can become applied. if you need help checking charge pressure, post another time and I will walk you through it.

[nhmx271]

If micos then are junk-If ausco dry brakes then see former. Charge pressure drop under load is critical, you can have 400 psi/no load/1800 rpm-stroke pump and psi drops more then 50 psi and you have pump problems-if that is the case then brakes will have drove through and they are trashed , however they would not hold at all. If you have dry brakes and cat has sat then can be iced up and can't be released-brakes are a saftey issue and should be gone through every year-never cut corners as you would not like the way your friends would console your grieving widow.

[cbender]

Thanks for all the input, I'll let you know how it all works out.

[johnny wrench]

bender you didn't say if the pumps are stroking against the brakes but i'm assuming they are. try the easy stuff first ,check brake coil ,should be @30 ohms if not replace it, make sure ground ring on bottom of coil is making good contact with valve.initial release is 160psi full release is 240psi on mico 545 brakes ,as far as I know ausco's weren't available in 94'. if prob is still there, check for 24v at coil with brakes off, if good voltage and still no luck check your charge pressure on the brake side of the valve if it's good prob is likely in the brake packs, possibly a broken rotor wedged up in the stack. I have alot of experience with these brakes and they are very reliable if they are not abused and serviced properly. good luck!

[cbender]

Ok, so this is what I love about working on snowcats....I checked the electrical and got the proper 24 volts at the brake solenoid (I did swap the coil with one of the others) and got in the cat to warm it up for the hydraulic pressure test. Well guess what?? Now the brakes release just fine and as a bonus, the tiller lift circuit works again after 4 years of having it jumpered to an unused rocker switch. You can't imagine how happy (but confused) I am.