M816 brake issue

[dreameweaver]

I have an M816 wrecker, when I set the brakes to use the winch the brakes will not release. The micro brake switch works well. It says to release step on pedal. Not sure if there is something else that may be wrong, so if anyone has ran into this problem any help would be great.

 

[73m819]

Need to step REAL hard on the brake peddle (harder then you did to set them), I have the same issue on the 819

 

[doghead]

I've never had that issue.

 

[73m819]

Think it depends on how hard the brakes are set in the first place, If I just use stopping brake pressure, they release fairly easy, if I really press the brake peddle down then set them, then it takes a bit of pressure to release them

 

[doghead]

Found this on Mico's site.

The brake lock does not incorporate a pressure limiting

function. Therefore, the operator should avoid

excessive brake pedal force when applying the brake

lock. Excessive force causes high pressure to be

locked in the brakes which can be difficult to release.

Changes in outside temperature can cause locked

up pressure to increase or decrease. A rise in temperature

can cause increased pressure in the brake

system which can lead to damaged brake system

components and made it difficult to release locked

brake pressure. To minimize the effects of temperature

changes, the brake lock must be released and reapplied

every hour.

 

[dreameweaver]

I have pressed the pedal hard, but brakes are hard and the pedal does not want to go down ??

 

[dreameweaver]

Ok few things to try. Will check back for any other info. Thanks

 

[crasheej]

I have pressed the pedal hard, but brakes are hard and the pedal does not want to go down ??

If the brakes are not adjusted correctle you can have locked up.

 

[gimpyrobb]

Sounds like you could just crack a bleeder open and release the pressure. Then they will either release on their own, or lower the peddle pressure to release the brakes.

 

[doghead]

So, today I had an interesting failure with the M819.

The steel brake line from Master Cylinder failed while my Mico Brake was engaged(when I went to release the brake). Without the ability to build brake line pressure, I was not able to release the Mico Brake.

I tried pressing the button a few times, while trying to move the truck, eventually it released.

I only moved it a few feet to a better location, to repair the line in the near future.

fwiw, My manual parking brake works fine, and it was chocked when the failure occurred.