That’s exactly the logic behind the old American idea of double drive units and unbraked steer axles which provided the best of all worlds situation of a 3 axle unit,which provides more contact at the road where it matters,with only weight transfer acting on the front of the trailer which puts weight onto the drive axles but without the effects of a braked steer axle causing the nose of the unit to dive thereby removing weight from the rear of the unit.
Seriously though i’m very unsure about that, an unbraked steering axle leading presumably to locked or locking drive axle(s) sounds to me like a recipe for disaster, be interesting to hear from our overseas contingent as to the system in practice.
In general I think it was more just a case of trading some overall stopping distance,caused by the loss of the braked front axle on a 3 axle unit,for less possibility of the drive axles losing grip and/or locking up,and then being pushed sideways by the trailer,because they didn’t lose the weight on them which having a braked front axle caused.In general,at least before the probable idea of modern braking systems,which seem to be able to manage the braking effort between unit and trailer axles front to rear,the idea seemed to work fine.
Therefore I’d bet that old 6x4 with unbraked steer idea would be able to stop a loaded artic better and more safely than a typical euro type 4x2 unit,at least of the same period,because at least when pulling a trailer the idea is to keep as much weight as possible on the drive axle/s under braking.But I don’t think that there’d be anyone around who’s used the two types of system in practice because I think it was only legal across the Atlantic and maybe Oz some years ago but never here or euroland.
Am I the only one with a headache after reading this thread?
I jack knifed once (pre ABS) in a Volvo F10 with a brand new tilt on the back.
rang the guvnor who went mentalist down the phone (probably thinking the cab was a write off)
The only damage done was a crease under the cab on o/s and a damaged dropside panel on tilt.
Got back to yard and next day fitter told me brakes had all flipped the cam down one side of unit which was the reason it jack knifed.I think I never noticed because the brakes on the trailer were so good being as it was new and the fact that it was early in my career so maybe I may not have recognised the signs.Also I was busy unwrapping my Mars bar as well
My truck has ABS/ASR and a seperate trailer brake, this past (and ongoing ) winter, due to lots of black ice, I have been in jacknife situations numerous times, sometimes the wind has pushed me and the truck naturally bends at the pivot point, sometimes it has been the rough surface of the packed ice that has pushed it out of line and sometimes this has happened at 65mph as a clear road became ice covered in the blink of an eye
So far I’ve been lucky, I haven’t gone beyond the point of no return, I’m amazed at how far that is as I’ve had a side window full of trailer almost every time, the only thing I’ve ever done is steer into it, hold on bloody tight and swear
Accelerating to try and get it straight and I would be in the ditch, braking by the pedal or the trailer brake and I would be in the ditch, the only way to get it straight again is to do everything very gently, no sudden yanking of the steering wheel or anything like that, just try and get it straight again and hope that it doesn’t suddenly grip and throw you the other way in a pendulum type swing guaranteed to fold it in half. Luckily I’m travelling on empty roads, so there’s nothing else to hit and I have the room to let it sort itself out… So far
Wheres the myth. 26 tonne of trailer will push 8 tonne of unit out the way.
Weight transfer lifts the load off the trailer axles and puts it on to the tractor.
If your lucky it stays in a straight line if not you jack knife.
If you got a nice dry road chances are it will stay straight in the wet who knows.
And for all the “ABS” bull if them trailer wheels dont lock out you got a big “lump” pushing a little “lump” about and if your on ice or snow its in the lap of the bloody gods.Once tractor and trailer get more than 15 degrees out of line your up there without a paddle.
Jonah 1:
:shock:
Am I the only one with a headache after reading this thread?
I jack knifed once (pre ABS) in a Volvo F10 with a brand new tilt on the back.
rang the guvnor who went mentalist down the phone (probably thinking the cab was a write off)
The only damage done was a crease under the cab on o/s and a damaged dropside panel on tilt.
Got back to yard and next day fitter told me brakes had all flipped the cam down one side of unit which was the reason it jack knifed.I think I never noticed because the brakes on the trailer were so good being as it was new and the fact that it was early in my career so maybe I may not have recognised the signs.Also I was busy unwrapping my Mars bar as well
What!!!Flipped the cam? so not had you worn out the linings but the lining carrier too!
Once heard this crap about Scania what a load of tripe.Your brakes got to be in one sad state to over ride an “s” cam.More like somebody had fitted o/s cams to n/s drums.
Bking:
Your brakes got to be in one sad state to over ride an “s” cam.More like somebody had fitted o/s cams to n/s drums.
They were !
He was a “proper cowboy operator”
I had a fitter come out to me one day because I couldn’t build any air up, he took the head off the compressor and there were 2 discs of hardened carbon with a hole about 2mm big in the center for the air to travel through
I also had an engine shoot 2 rods through the engine block going up Reigate Hill on M25
He had photocopied o licence in windscreen (and that didn’t belong to him)
etc etc etc
Jonah 1:
:shock:
Am I the only one with a headache after reading this thread?
I jack knifed once (pre ABS) in a Volvo F10 with a brand new tilt on the back.
rang the guvnor who went mentalist down the phone (probably thinking the cab was a write off)
The only damage done was a crease under the cab on o/s and a damaged dropside panel on tilt.
Got back to yard and next day fitter told me brakes had all flipped the cam down one side of unit which was the reason it jack knifed.I think I never noticed because the brakes on the trailer were so good being as it was new and the fact that it was early in my career so maybe I may not have recognised the signs.Also I was busy unwrapping my Mars bar as well
What!!!Flipped the cam? so not had you worn out the linings but the lining carrier too!
Once heard this crap about Scania what a load of tripe.Your brakes got to be in one sad state to over ride an “s” cam.More like somebody had fitted o/s cams to n/s drums.
It’s not just worn out shoes that can throw a cam over, flat spot on the cam roller or worn out cam bush.Broken return spring maybe. just general poor maintenance.
If anyone caught 24 Hours in A&E there was a driver on there who just clipped the kerb and then jacknifed. There but the grace of (Choose your superior being) go us.
In years gone by when I was paid for things like this to investigate, a poorly maintained Load sensing valve, on the tractor unit would more like be the reason for a JK. Fitters used to tie them up, to get the tractor through a test, and more than often forget to undo them!
Winseer:
If your trailer starts to swing around the side of you, then you floor the accelerator (in the dry and straight) and flick the trailer brake/handbrake to effectively “jerk the combination straight again”.
If you’re going around a corner, it won’t work. If it’s icy it won’t work. If it’s wet, it might still not work.
There’s a reason of course that we have a yellow airline as well as a red one. You can drive it around on “only” the red, but I wouldn’t advise it. Shunters do it all the time, but even they run into the occasional bother come the rain and snow…
Are you for real?
Please enlighten me as to why we have a yellow airline,as well as a red one? you sound like a professional driver who i could learn a few things from. Flick the handbrake lol Wtf,i wouldn’t let you drive my dyson round the living room.
It’s scary that some people don’t know basic things, Then naive people like Shoshaye try to take the mick out of someones obviously good advice, It’s the sort of thing that most drivers would already know.
Shoesaye, does your dyson not have a secondary braking system? this thread has gone on for many months and I am still learning from it. Like Phil I am learning that there are too many people driving trucks who do not understand the basic controls.
The handbrake valve has two purposes, the hand valve has three positions, off, on, and locked on. The next time you are on a straight quiet road, try it out it may just save your life or save you blocking the road for 12 hours. Before this type of valve we had the “Dead Mans Handle” like those fitted to Volvo F88 and Scania 112. We also used the Clayton Dewandre type valves which also had two positions and you had to push the lever forward to charge the system before you could release the parking brake.
Long before Anti Blockier Systems and Girling Skidcheck, we used cadence braking techniques, before we had air gauges and buzzers we had semaphore flags that popped up out of the dashboard or demister slots
Winseer:
If your trailer starts to swing around the side of you, then you floor the accelerator (in the dry and straight) and flick the trailer brake/handbrake to effectively “jerk the combination straight again”.
If you’re going around a corner, it won’t work. If it’s icy it won’t work. If it’s wet, it might still not work.
There’s a reason of course that we have a yellow airline as well as a red one. You can drive it around on “only” the red, but I wouldn’t advise it. Shunters do it all the time, but even they run into the occasional bother come the rain and snow…
Are you for real?
Please enlighten me as to why we have a yellow airline,as well as a red one? you sound like a professional driver who i could learn a few things from. Flick the handbrake lol Wtf,i wouldn’t let you drive my dyson round the living room.
It’s scary that some people don’t know basic things, Then naive people like Shoshaye try to take the mick out of someones obviously good advice, It’s the sort of thing that most drivers would already know.
Shoesaye, does your dyson not have a secondary braking system? this thread has gone on for many months and I am still learning from it. Like Phil I am learning that there are too many people driving trucks who do not understand the basic controls.
The handbrake valve has two purposes, the hand valve has three positions, off, on, and locked on. The next time you are on a straight quiet road, try it out it may just save your life or save you blocking the road for 12 hours. Before this type of valve we had the “Dead Mans Handle” like those fitted to Volvo F88 and Scania 112. We also used the Clayton Dewandre type valves which also had two positions and you had to push the lever forward to charge the system before you could release the parking brake.
Long before Anti Blockier Systems and Girling Skidcheck, we used cadence braking techniques, before we had air gauges and buzzers we had semaphore flags that popped up out of the dashboard or demister slots
Wheel Nut:
Long before Anti Blockier Systems and Girling Skidcheck, we used cadence braking techniques, before we had air gauges and buzzers we had semaphore flags that popped up out of the dashboard or demister slots
bloody hell wheel nut, how old are you?
Still young enough to remember demisters, some of these proper old hands only had 3 greatcoats and a potato
) winter, due to lots of black ice, I have been in jacknife situations numerous times, sometimes the wind has pushed me and the truck naturally bends at the pivot point, sometimes it has been the rough surface of the packed ice that has pushed it out of line and sometimes this has happened at 65mph as a clear road became ice covered in the blink of an eye 
