Catastrophic parking brake failure

[dave wagner]

While driving to work the other day in my m135 about 8 miles into the drive going around 45mph. A massive bang I immediately let off the throttle and looked in the mirror to see something sliding on the road and going in the ditch. My first thought was a tire blew out. When I stepped on the brakes they were gone. Looked at the air guage zero. Next idea one of the air tanks exploded. Pulled up the parking brake lever next. Lever pulls all the way up with no resistance. Luckily I was going up a small hill in the predawn no traffic road so it wasn't as bad as it could have been. Looked under the truck with my cellphone light wow! The parking brake drum blew up ripped off the brake lining and mounts, tore out some air lines. After I got the truck back home and surveyed the damage it looked like I could repair all the damage with my parts truck. These pictures are of the parts I found in the ditch and the drum off the donor truck. After inspecting my other m135 very closely it has some hair line cracks to. I found new parts so I don't need parts, just don't want anyone else to have a similar experience.

 

[Whitey]

Wow. Glad you're OK.

 

[nw42]

It looks like those parts have been cracked for 50 years

 

[gunboy1656]

How much drivers seat is left? Had to be a real eye opener first thing in the morning.

Glad you found a good set of parts, check over the rest of the system real good.

 

[m1010plowboy]

Brake failure

Thanks for posting this Dave. You know you're going to take a beating for not catching this with a pre-trip inspection and I appreciate the education without injury. We all learn from these incidents and fortunately are ultimately responsible for preventing them. I will re-inspect my Park brake today as will a lot of other folks, thanks to you.

It's not a component one would expect to detonate. Then again, it never is.

This will help drive the need for additional inspection time spent on old steel, I hope.

Insert guy eating Popcorn.

 

[DeucesWild11]

Well I don't know the early deuces but perhaps don't use a drum with a crack in it??

 

[islandguydon]

My next stop would have been to a quarter wash to spray out the chit all over my seat from the BANG.

 

[dave wagner]

About missing the crack in the drum. Just got around to fixing this. It happened last fall thats why the peices are rusty. When it broke the peices I found were new brakes. The donor truck drum was an easy catch from over 20 foot away. My other M135 was not that easy, I wire wheeled off the surface rust and had to look very close to see a small crack. What I think started these cracks was someone leaving the parking brake on for a long time while driving.

 

[Stretch44875]

That drum is spinning pretty quick, especially on the m35a2's with the overdrive. Wouldn't take much for one to go boom if it was cracked. I've looked at the drums on the trucks, but never thought to look for a crack. Really bad luck for it to have take out the service brakes too.

Just figured it up, on my truck with the custom .71 overdrive, it's spinning 3500rpm at 2500rpm engine, in 5th gear.

 

[Ferroequinologist]

Back in steam days flywheel failures were known to kill many and destroy whole boiler rooms at factories. Lots of potential energy stored up in a rotating mass.

I never thought to check the drum for cracks either- it will become another check box on the list.

 

[butch atkins]

Need to tell this.SIS (self inflicted stupidity).I let my M211 parking brake get kind of loose,would still hold but you had to jerk the s#@% out of the E-brake handle to get it to stay up .The parking brake will not hold the truck under power when driving it.Dont know about M35 brake ,but there are 2 cams that actuate the parking brake band ,I let mine get out of adjustment and the cams stuck the parking brake band to the drum.They were jammed and didnt release.I had a hot date waiting to go" trail riding",jumped in truck,fired it up headed out to a sure thing .About 1 mile from the house ,came to a stop sign and the most awful smell came from the truck."OOH OOOH THAT SMELL,CANT YOU SMELL THAT SMELL".Knew instantly what it was.Had to drive back home ,wait for E-Brake band to cool off enough to adjust it to the proper clearance,took alot of adj cause it wore a lot of the lining off.Got lucky didnt have disaster like yours.MORAL OF THE STORY. MAKE SURE YOU ADJUST THAT PARKING BRAKE LINKAGE EXACTLY AS TM9-8024 SAYS TO.IF IT TAKES MORE THAN 3 CLICKS ON THE PARKING BRAKE HANDLE .YOU NEED TO LOOK AT IT. And yes i got lucky twice that night. LOL.good luck to all on your projects

 

[doghead]

The M35A2 Parking brake drum is not cast.

 

[Gunfreak25]

Remember guy's, these trucks are aging. I will be inspecting mine with a fine tooth comb, thanks for posting.


I also ran across a post awhile back where a guy had the steering gear shaft on his M211 break clean off during normal daytime driving. BOOM. Zero steering. He was very lucky to have both the truck and himself unharmed.

 

[rosco]

That drum exploded from the extreme heat generated by leaving the E-brake on while driving. I once rebuilt/re-lined the emergency brake in my M37, adjusted by the book etc. My wife jumped in it and took off for the store, or something. Same exact thing. She left the brake on - about 45 MPH. It exploded: first the smell, then smoke, then the noise......... and finally the OH Sh..........

 

[maddawg308]

Now just think of all the PM work it's gonna take to get the seat foam cushion material out of your a s s. You'll be crapping canvas for weeks.

 

[neilhank]

Close call there.

 

[RedbeardTheZombieHunter]

Sounds like a pretty high pucker factor! Lucky you didn't pinch a hole in the driver's seat upholstery! Glad you and the truck are ok and no one got hurt! A flung chunk of cast iron from that drum could make a really expensive dent in a Mercedes! I think I'll be adding a detailed parking break inspection to the TTD list on my deuce!

 

[dave wagner]

Check this out. I got two new still in the box drums to fix both trucks. Who would think to check for cracks, duh! As I was tighting the drive shaft bolts it became apparent I should have.

 

[butch atkins]

Maybe time to look for a good used one.Kind of hard to get 2 bad NOS parts .Are you doing something you shouldnt be ?best friends wife,robbing banks,stealing social security checks from mailboxes?Just kidding,that is some kind of bad luck.Be thankful you didnt injure yourself or someone else.Good luck on your project

 

[Gunfreak25]

Jesus, I am going to get mine magnafluxed while I have the D-shafts out. I reccomend everyone else do the same. Not cool.