like the title says. i got 2 prohibitions yesterday, one on the unit for a cracked brake disc, and one on the trailer because it had an 18" flat spot on it.
they accepted that it wasn’t the sort of thing a driver is likely to spot. they were quite decent about the whole thing, however they didn’t make me a coffee.
it turns out that every time the pull one of our lorries, they find a lot of faults, they have never given one of ours a clean bill of health.
and you know what’s really funny? my boss was the former chairman of the RHA.
a friend on mine bought a unit from a main dealer with a brand new MoT, after approx 1 month, he got tugged by VOSA for a spot check, they found a cracked brake disc on the unit.
they gave it an immediate PG9, he had to drop his trailer there and then, was allowed to take the unit to a place to be repaired and only allowed to drive at a max speed of 25Mph.
he had to get a friend to pick his trailer up and take it back to thier yard
limeyphil:
like the title says. i got 2 prohibitions yesterday, one on the unit for a cracked brake disc, and one on the trailer because it had an 18" flat spot on it.
they accepted that it wasn’t the sort of thing a driver is likely to spot. they were quite decent about the whole thing, however they didn’t make me a coffee.
it turns out that every time the pull one of our lorries, they find a lot of faults, they have never given one of ours a clean bill of health.
and you know what’s really funny? my boss was the former chairman of the RHA.
So what did they say about the flat spot? Isn’t that 3 points?
bobthedog:
Ridiculous… Every heavy vehicle on discs will have heat radiation cracks. It seems VOSA are just looking for new victims.
true, but the disc on my mates truck was a full on crack, all the way through the disc from inner edge to outer edge
i was i the depot were i worked once and a truck pulled it to tip someone noticed he had a puncture on his front wheel must off just happened anyway tyre firm come out to change the tyre and as he was breaking the tyre off the rim the rim fell in two 5 pieces, i had never see that before after that the fitter replaced both rims as the other one had hairline cracks in it
bobthedog:
Ridiculous… Every heavy vehicle on discs will have heat radiation cracks. It seems VOSA are just looking for new victims.
true, but the disc on my mates truck was a full on crack, all the way through the disc from inner edge to outer edge
i was i the depot were i worked once and a truck pulled it to tip someone noticed he had a puncture on his front wheel must off just happened anyway tyre firm come out to change the tyre and as he was breaking the tyre off the rim the rim fell in two 5 pieces, i had never see that before after that the fitter replaced both rims as the other one had hairline cracks in it
Disc brake technology on trucks is a relatively new one so it’s not right to blame drivers when problems show up.The rims issue sounds scary never heard of it on anything in the past.Maybe there should be more testing of disc brakes.Were those rims alloy ones because they’ve been used for years with no probs?.
The problem with cracks in the disc is one that can only be properly checked when , the unit or trailer in question is over a pit or you get under the unit, The heat from brakeing has not yet been beaten and unless they can find a steel/metal that will dissipate heat quickly then you will STILL be getting such reports in the future, The manufacturs know about the problem but what is their answer■■?
brit pete: The problem with cracks in the disc is one that can only be properly checked when , the unit or trailer in question is over a pit or you get under the unit, The heat from brakeing has not yet been beaten and unless they can find a steel/metal that will dissipate heat quickly then you will STILL be getting such reports in the future, The manufacturs know about the problem but what is their answer■■?
Ok, I get that, but what about drums then? They didn’t crack (often)
Is it because the discs stop better so we brake later, which generates more heat & leads to cracking?
Also do VOSA inspect the disc thoroughly & try to identify if it’s a recent crack i.e. one that has appeared since the last safety inspection or is a crack a crack? If it’s the latter then that’s a bit unfair, the crack, like a cut in a tyre or a crack in a windscreen could have only just occured, it’s a bit draconian to be targeting this purely to make up their numbers, if it’s a safety isssue then that’s another story, but it would have to be a pretty serious crack to put the disc at risk of breaking up.
Do not agree with the brakeing later theory, but do agree that they have better stopping power, would it not be possible that set up which directed air on to the disc when the vehicle was moveing some thing like a cone shaped set up, just a idea as this may help dissipate the heat from the disc???and so help reduce the problem of cracks in the disc,
The truck racers use a water cooled system, they weigh about 5tons & do 100mph, I would’ve thought there is as much if not more heat generated from stopping 44tons from 56mph, if discs are cracking then it’s only through the heat so if the race trucks need to water cool their discs how are discs supposed to cope with the repeated use of everyday trucking?
I don’t know if air cooling will have any great effect, is it not the initial temperature that causes the cracking rather than a gradual cooling down process?
newmercman:
The truck racers use a water cooled system, they weigh about 5tons & do 100mph, I would’ve thought there is as much if not more heat generated from stopping 44tons from 56mph, if discs are cracking then it’s only through the heat so if the race trucks need to water cool their discs how are discs supposed to cope with the repeated use of everyday trucking?
I don’t know if air cooling will have any great effect, is it not the initial temperature that causes the cracking rather than a gradual cooling down process?
Truck racing is hardly a good comparison, they will use the lightest discs they can, to use water cooling to prevent brake fade is one thing. 44tonne trucks going down Sutton bank or the Katzenbach. How much payload are you going to take up with your onboard water tank?
Maybe the council could dig water gulleys into the road, then if the truck manufacturers put a scoop under the truck. Sounds like a record breaking run of the Flying Scotsman
I had staged retarders on my dump trucks, it would slow down and hold a 45 ton dump truck on a 30 degree slope to tickover speed, I think there were 6 or 7 stages on the retarder handle, this could surely be used on trucks in place of the feeble engine brakes used now, I can’t remember who made the retarders now but they were very effective.
I had staged retarders on my dump trucks, it would slow down and hold a 45 ton dump truck on a 30 degree slope to tickover speed, I think there were 6 or 7 stages on the retarder handle, this could surely be used on trucks in place of the feeble engine brakes used now, I can’t remember who made the retarders now but they were very effective.
I don’t know what the volvo trucks are like but the B12 volvo coaches I used to drive had very good retarders in additon to the ex brake. it was like doing an emergency stop when I flicked the handle all the way down at 62mph. They made a whining noise
@steve-o &brados the retarder set up and also the jake brake are good but it is the discs that are lacking in quality and strength, so the manufactures must do more R&D and quickly as they are the ones who wish to sell their product to the customer
Wheel Nut:
Truck racing is hardly a good comparison, they will use the lightest discs they can, to use water cooling to prevent brake fade is one thing. 44tonne trucks going down Sutton bank or the Katzenbach. How much payload are you going to take up with your onboard water tank?
Maybe the council could dig water gulleys into the road, then if the truck manufacturers put a scoop under the truck. Sounds like a record breaking run of the Flying Scotsman
Maybe we need carbon discs
Truck racing is the only comparison, unless there’s something else lorries are used for that I don’t know about & I never said that it was an option for road going vehicles, the point was, that as Britpete said, they need better cooling to prevent discs cracking, the brake component manufacturers must be aware of this as they are heavily involved in the truck racing scene & came up with the water cooling idea.
Also a truck loaded to 44t will be overloaded going down the Katzanbach & having driven that road many times, surely it wouldn’t need a single brake application if driven correctly? Proper use of the exhaust/engine brake/retarder would mean that the discs stayed cool all the way down
brit pete: @steve-o &brados the retarder set up and also the jake brake are good but it is the discs that are lacking in quality and strength, so the manufactures must do more R&D and quickly as they are the ones who wish to sell their product to the customer
Why not just go back to drums until they’re all certain that they’ve got it right.They’ve been bringing wagons of all sorts and weights down the alpine passes for years on drums using exhaust brakes without many issues so why make problems for ourselves.Jake brakes were mainly only fitted to Yank type engines Cat,■■■■■■■ etc.? which most European trucks don’t have these days.
Never had trouble with cracked discs, but recently had trouble with the calipers not floating/centering on the disc (haldex) because the sliding spigots had become solid, eventually only the inside of the disc is being braked pushing the hub onto the outside bearing. Had a wheel bearing fail and suddenly seize, scarey moment and a decent tyre trashed into the bargain so pulled all the wheels off and found a second one. Would help if they put gators on both spigots, not just the top one
Cracked brake discs are nothing new, should be checked at each safety inspection specifically for cracks. Monitor the crack and when it reaches a certain length / depth change the disks and pads as a set.
Calipers seizing and severe cracks on discs is really down to poor maintenance. Telma retarders had a weight penalty and never really found favour in the truck market, jake brakes are excellent if setup right.
Drums had there own problems, especially when asbestos free linings were used. An 18 inch flat spot
Vosa are clowns but if they find fault with your truck on every occassion then former RHA chairman is a bigger clown.
