Why dont they make them anymore,it was a lever on the dash that activated the trailer brakes,thus saving your unit brakes wearing out,useful when an o/d as the freight forwarders trailer would wear out quicker than my unit,as they paid for the maintenance and tyres/breakdown.
toby1234abc:
Why dont they make them anymore,it was a lever on the dash that activated the trailer brakes,thus saving your unit brakes wearing out,useful when an o/d as the freight forwarders trailer would wear out quicker than my unit,as they paid for the maintenance and tyres/breakdown.
you mean like the switch he used in the cab in blackdog when the truck was about to ram him 
Firstly, that lever did not operate a JAKE brake. It operated the trailer brakes. I agree that they were a godsend, especially to us OD’s pulling other peoples trailers, you could predominantly use the trailer brakes and aviod wear and tear on the units brakes.
The JAKE Brake was an engine brake manufactured by JACOBS (hence JAKE Brake) which operated on the camshaft of the engine, retarding the engine speed. The JAKE Brake fitted to both my CAT powered ERF EC12 and my ■■■■■■■ powered Peterbilt would pretty much bring them to a halt without the use of the foot brakes at all.
They were more commonly called the Deadman, and handy as mentioned for ferry trailers, that’s if you were lucky to pick a ferry trailer up that had any brakes left 
Most trucks had them, either on the column Volvo 86 /88 stylee or on the dash Scarnia likee
Someone told me that steering locks for cars were never designed to deter car thieves,as not strong enough,the lock was for maintenance for the car,when it was needed to have the wheels straight,like on a open pit in the garage.Are there any other reasons,one strong tug on it,it breaks the lock anyway.
It was ok for you guys using the trailer brakes all the time. But anyone not owning a Scania, had to do all the braking with the unit, cos the trailer brakes were shot!
I think the trailer brake lever was removed due to the ABS then EBS braking systems, having ‘anti-lock’ capabiliites.
Someone might correct me on this. But I think that the trailer brake was intended for slowing the trailers down steep descents,
on loose surfaces to resist jack-knifing. Bearing in mind the weights that Scanias were plated to run at. Which was about 52 tonnes
train weight, if I remember.
It was excellent for moving the sliding 5th wheel though 
Pat
And pulling up to traffic lights without touching the unit brakes.
never seen the old ones but was in a new renault premium that had it. just a switch behind the handbrake.
those levers in the old scanias were spot on for keeping your duster behind or was that just me 
This lever was more commonly known as the “DEADMAN”,Uncle Tony taught me “use whenever possible to save my unit brakes” Back then we only had 4 axles in total.
I was told they did away with the trailer brake as they couldn’t get it to work with the ABS. I am sure they could if they wanted, but, it wouldn’t have any ABS.
i drove a 4 series scania on a S reg that had this lever fitted was good when i had another trailer behind me !! as the brakes on the unit werent the best i had felt anyways although they did work correctly !!
In olden days when lorries had 3 airlines Blue, Yellow and Red the blue line was our secondary braking until the manufacturers came up with a 2 line system. The old dead man’s handle let air through the blue line. My first 2 line truck was a 1984 MAN at Norman Lewis.
We still have the secondary brake on modern trucks, it is just the first stage bit before the handbrake locks.
DAFMAD:
I was told they did away with the trailer brake as they couldn’t get it to work with the ABS. I am sure they could if they wanted, but, it wouldn’t have any ABS.
Strange, as we have ABS trailers overe here, and every tractor unit has a trailer brake lever on the dash. Oh and we dont have a seperate ABS cable here, all electrical connections are made through the 1 plug in.
BigJon:
DAFMAD:
I was told they did away with the trailer brake as they couldn’t get it to work with the ABS. I am sure they could if they wanted, but, it wouldn’t have any ABS.Strange, as we have ABS trailers overe here, and every tractor unit has a trailer brake lever on the dash. Oh and we dont have a seperate ABS cable here, all electrical connections are made through the 1 plug in.
Agreed, but, that was Scanias reasons given.
The relative theory behind the “Deadman” trailer brake goes back to old (and current) practice of horse and cart going downhill.
To prevent the weight of the cart pushing the horses downhill and losing control and prevent a “runaway” situation :-
a chained attatched slipper skid pad is placed and jambed under the rear axle wheels.
Thus creating a high restistance friction brake with the road surface and greatly reducing downhill speed, and preventing a “runaway” incident , whilst still being able to steer and manoever.
Same theory can be applied to handbrake in a car going downhill in snow or icy conditions at reduced speed and still be able to steer , (dont try it with a moving 4x4 eg L/rover , as they have transmission handbrakes and it could be a very costly mistake 
)
Car Rally drivers make use of handbrake very effectively.
Obviously, as technology development moves on and design manufacture integrates new systems , the truck braking system has moved on too.
I think the LGV handbrake does (or did ) still apply the (rear axle - rigids) Trailer brakes - in the secondary position before it goes into full parking brake mode (all wheels all axles),
as parking brake lever is moved (applied) - just before it flicks over into locked park position.
As said prior ,
the “jake” brake is an engine speed revolution retarder, which is funnily enough where the “exhaust brake” comes into play too 
“exhaust brake” applied - engine cannot release exhaust gases so chokes the engine into slowing revolutions. Happy days
whats a break 
hat coat TAXI
The Jacobs (Jake) engine brake is a compression brake, it closes the exhaust valves which basically stops the piston from pushing out air on the exhaust stroke, the increased resistance then slows the engine, this is transmitted through the rest of the driveline & the vehicle slows down, higher revs are better because of the increased pressure build up in the cylinders. An exhaust or turbo brake works on the same principle, although it closes the exhaust & not the valves, they’re lighter, less complicated/expensive & also less efficient.
A retarder comes in two main forms, electrostatic & hydraulic, the electrostatic ones work independant of engine speed & work like an electric motor except the polarities are, I think, the same rather than opposite, therefore instead of making the shaft, in this case the prop revolve, they try to stop it. The hydraulic ones need revs as their basic principal is to engage a pump that pushes fluid through small holes, the pressure/resistance required to do this increases with speed & this slows the vehicle.
Seperate controls for independant accuation of trailer brakes stopped when the latest generation of ABS was introduced in around 92, well in GB anyway, the europeans still had them & as far as I know the Scandinavians still do.
One thing I find troubling is that people think it’s a good thing that you can use trailer brakes to save your unit brakes, it makes sense until you glaze the trailer linings & then have to rely on your unit brakes to stop in an emergency, anyone who has shunted a loaded trailer with just the red line on will tell you that the unit brakes alone are not going to stop you very quickly at all, with that in mind it’s probably a good job they are not fitted anymore or the HATO boys would be very busy closing the highways & byways of Britain as the emergency services hosed mangled drivers from their wrecked cabs after they run into the back of stopped vehicles at 56mph
nick2008:
whats a breakhat coat TAXI
according to the WTD a break must be taken after a period of 4.5 hrs driving and be 45 mins before you can commence with another 4.5 hrs driving…
can i share your taxi mate…