Sometimes air brake on international grab and dont release.

[Georgia Iron]

I have a 89 model international 9400 series tractor truck that is converted to a dump truck. Sometimes (10 % chance) when I really hit the brakes they grab and don't let go when I take my foot off. I either have to tap the pedal or wait until they release on there own. This happened to me while backing a load up a hill a week ago and the brakes grabbed and I was slow letting out the clutch. It killed the engine and the steering wheel spun out of my hand and caught my thumb. Broke my thumb. I dont brake easy but this sure as hell sucked.

My truck is old and has wear. What typically causes the air brakes to do this?

 

[RZucker]

I have a 89 model international 9400 series tractor truck that is converted to a dump truck. Sometimes (10 % chance) when I really hit the brakes they grab and don't let go when I take my foot off. I either have to tap the pedal or wait until they release on there own. This happened to me while backing a load up a hill a week ago and the brakes grabbed and I was slow letting out the clutch. It killed the engine and the steering wheel spun out of my hand and caught my thumb. Broke my thumb. I dont brake easy but this sure as hell sucked.

My truck is old and has wear. What typically causes the air brakes to do this?

Check for a sticky brake pedal, or the pedal valve may have junk in it not allowing the plunger to return to the off position. Floor mount pedal or is it hanging from the fire wall?

 

[Tenwheeler]

Take the pin out of the brake pedal and remove it. I thank it has a pin and roller under it. Those push on a piston into the foot valve. Get it out and clean all that up. If that's not it post back.

 

[Birken Vogt]

Relay valve possibly.

 

[Hallback]

Ahhh, the ol broken thumb syndrome.
You learn to wrap thumbs over wheel instead of under with manual steering.
I still drive that way just because of that.

 

[Georgia Iron]

10-4 I will check the pedal. I did clean the dirt from around it, it was caked under it pretty good. But it still has the issue. The truck has power steering. I was fighting the wheel hard, which I think is because it got up next to a concrete curb. I had gloves on which did not help with my grip one hand was on the gear stick and one on the wheel. When it broke free of my hand it spun fast and one of the middle sections jammed straight into the end of my thumb and dam did that smart me.

You know we all have close calls, some way too close.

I have been almost hurt in so many ways dealing with saws, trees, loading concrete, moving ramps, and misc. stuff working with loads. Most everytime I seem to just slip by and and say dam that was close. This and an excavator door got me. I dont know how I did not loose my fingers in the excavator door when it decided to slam shut when the weight tipped foward and the outside door latch let go and slammed into my fingers in the dark. NEVER put your hands on the cab where the door closes EVER. Or just always make sure the door is closed.

It really gets me to get hurt in what seems to be in a way that you should not get hurt by a reliable machine. That truck has not let me down yet but it broke me. I hope you can see my humor in that.

 

[Muffler Bearing]

Time to check the action at your wheel ends. Look for a bent S-cam tube. Grease those S cams really good check to make sure none of them are sticking. The spring that returns the pushrod isn't nearly as strong as the air chamber applying them.

 

[Wes J]

I tend to agree. I have seen cams and rollers that were badly rusted and sticky. Mostly on van trailers that sit parked with the spring brakes on.

 

[Mother Deuce]

Ahhh, the ol broken thumb syndrome.
You learn to wrap thumbs over wheel instead of under with manual steering.
I still drive that way just because of that.

The old manual Kenworth center points would teach that class quick off highway!

 

[RZucker]

The old manual Kenworth center points would teach that class quick off highway!

When I was 13-14 years old (Jurassic Era) I drove a 1948 KW ex off road logger with 24' rubber and a cernterpoint front end hauling water to a well drilling rig, That old beast taught me early on to keep my thumbs out of the spokes. 220 Cummins with a 4x3 trans. It's still out there some where with a big A-frame boom on the back. I still remember the cab serial number was 0001.