Is it possible to break a prop shaft by mis treating the truck or is our TM just getting overly paranoid about one particular (malcontent) driver whose currently living very much on borrowed time ■■?
I worked in recovery for a few years so he’s asking my opinion. I’ve certainly recovered quite a few but never put them down to sabotage, I would’ve thought junking the clutch would be much easier.
The only way to break a prop shaft is either by driving over something and hitting the prop shaft or it will break from old age cant seem to think of any other ways
Chas:
Is it possible to break a prop shaft by mis treating the truck or is our TM just getting overly paranoid about one particular (malcontent) driver whose currently living very much on borrowed time ■■?I worked in recovery for a few years so he’s asking my opinion. I’ve certainly recovered quite a few but never put them down to sabotage, I would’ve thought junking the clutch would be much easier.
Would imagine it would take a pretty determined driver to break a prop shaft IMPO, guess it’s not impossible but imagine those things are pretty rigid!!!
Clutch would be easier to break by buring it out (i imagine 
)
Not sure though how you would exaplain to TM how it happened as surely recovery firm/dealership would detect foul play when they repair it■■?
bubsy06:
The only way to break a prop shaft is either by driving over something and hitting the prop shaft or it will break from old age cant seem to think of any other ways
TM’s line of thought is he’s been purposely abusing the gearbox, slamming gears etc to break it !
Personally I reckon they should just have a punch up outside the gates & get it over with 
Chas:
bubsy06:
The only way to break a prop shaft is either by driving over something and hitting the prop shaft or it will break from old age cant seem to think of any other waysTM’s line of thought is he’s been purposely abusing the gearbox, slamming gears etc to break it !
Personally I reckon they should just have a punch up outside the gates & get it over with
You would break the gearbox or clutch not the prop shaft.
punch up sounds better
If a propshaft were to go as such it will normally be the U/J. I would’ve thought it would be difficult to make one go, but I suppose you could shorten its life. 
DAFMAD:
but I suppose you could shorten its life.
Bloke quickly hides oxyacetylene torch as he see’s the guv walking over chuntering
"onest guv, it just broke on it’s own 
"
In my experience it was the half shafts that used to break - especially on tippers working on rough ground.
I’d say the only way to do it would be to dump the clutch on full engine revs wit the handbrake/ brakes on . However you’d be as likely to bugger up the clutch, gearbox or diff. My guess the most vulnerable would be the gearbox.
If you wanted to knacker the prop shaft inject some grease / sand mix into the UJ greese points.
You can easily snap the propshaft to universal joint bolts by engaging reverse whilst still rolling forward and then letting the clutch out.
So in answer this could be done deliberately if a driver had a mind for it.
Drive shafts would be the first to go in my opinion, as they offer the most weakness.
Never seen a broken propshaft on a commercial vehicle, but have seen plenty of halfshafts g/boxes and clutches u/s.
The Universal Joint on propshafts does go but to sheer a propshaft really does take some effort!
Recovered many motors where the UJ had gone mainly due to wear and tear, more often than not a decent fitter will spot the wear before it breaks out on the road.
1:40 in and you will get the idea of what happens when a prop really does let go.
I’m on the 8 wheel tippers and i’ve had 2 centre bearings go (on 2 different trucks) and 2 rear UJ’s (again 2 different trucks) but never broken the prop…was just put down to general wear and tear, although i’ve been told Scania’s are prone to UJ’s going■■?
IMO as an retired mechanic you’d be far more likely to break the clutch or gearbox before a propshaft lets go…
I worked with a guy that drove a six wheel ridgid with a 24ft body,it broke two prop shafts.I believe the longer the shaft the more chance of it snapping!
Tractor unit’s are unlikely to go as easily.
Props usually go through lack of grease or running out of line !! Centre bolts broken are the favorite.
Ellies Dad if it was a stretch that could be the problem, as another section of propshaft is added and has to be balanced and in alignment. Ther is also a centre bearing between the two shafts which maintained and aligned
Years ago when I was working as a fitter for Jock Kelly in Nottingham, I got dragged up to the office to find the little swine having a fit because one of the units had dropped a propshaft on the M1, busting a fuel tank.
Jock accused me of not checking the prop bolts; I went off to fetch it, found that the gearbox housing had actually broken and the mainshaft stub was hanging out of the back, still attached to the prop. Suspected cause was driver getting mixed up between ERF and Seddon Atkinson gearshift patterns; 9-speed Fuller Roadranger, remember them? 
Either that or his head had been in David Brown mode; older drivers’ll know what I mean.
Towed the unit back, straight into the workshop, took the prop off and stomped upstairs into Jock’s office, and without a word dumped it on his desk; all prop bolts intact! Jock’s tea went flying, I walked out before he could open his mouth, and went home.
Came back in the following morning; nothing was ever said but he never accused me of shoddy work again!
I saw a Daf twist the prop off on a hill, and have heard of other occasions. It takes a bit of doing but it is most likely when you are spinning your wheels and they suddenly catch traction again.
Halfshafts on Scanias are a weak spot, but they take a hell of a beating before they give as a general rule. All it takes for a prop to throw a fit is a vibration from either a balance weight rusting off or a dry UJ, something like that, or a radical shock.
Centre prop bearings are the favourite cause though.
have had a U/J come off and the drive shaft drop while on a freeway once, and my TM tried to pin it on me, being a newbie at the time, i still had my doubts so ignored him, went off and rang my old man, got the required information from him, which was that the most probably cause was the workshop not greasing them every month at LEAST, i had been driving said truck (1984 Volvo F7 - this was in 2006) for at least 6 months and never seen it pulled in for maintenance, so when i tackled the TM and bit back he tried to make out that i was paranoid that everyone was out to get me
im sure everyones got TM relations stories thats off the point, but having seen a few other drivers drop drive / tail / half shafts since, even good drivers who look after their gear, i would suggest that its not preventable by the driver nor is it caused by negligence or abuse, and that it is in fact down to lack of general maintenance by the mechanics.
Your TM is to blame as he must be using the cheapest labour to maintain the vehicles.
He is probably getting a fitter to do the work instead of a mechanic.
You can’t [zb] up a prop or U/J by your driving style.
Typical TM “Can i blame the driver who isn’t here”?