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Today I got a letter from the Registrar of Motor Vehicles which said..

Dear Mrs Beaumont.

IMPORTANT SAFETY INFORMATION FOR TRUCK & BUS DRIVERS.

On the 18th August 2014, a fatal crash occurred at the intersection at the bottom of the South Eastern Freeway in Adelaide involving an out of control truck.
I am writing to remind all truck & bus drivers of your legal requirements to comply with Australian Road Rule 108 when driving down a steep road. That is, you must use a low gear to limit the speed of the vehicle without using the primary (foot) brake.
The enclosed brochure explains this law & the serious consequences that follow if drivers do not comply.
Please read this information carefully and consider the risks. Never attempt to drive a vehicle if you are not familiar with it's braking systems and controls.
Yours sincerely
Julie Holmes
Registrar Of Motor Vehicles
8 Dec 2014


When we were taking the bus over to the mechanic last week I followed a truck down the hill and our speed was just on 30kph, he didn't touch his brakes at all for the whole drive down the hill. But as expected a super dickhead truck did, he passed us like we were not there. Hoping the cameras caught him. This also brings me to a couple of other questions. 1/ Remember when I was having all that grief about going down that hill to have the VIN # read and they were INSISTING I did go down that hill even when I said I had no idea about the braking system etc?? and 2/ What are we really classed as? a bus or a Motorhome??

I'd say we are classed as a heavy vehicle be it bus or motorhome.

George

For the purposes of vehicle size etc, it is a bus, for licence requirements, it is a motorhome or panelvan/Pantech truck, i.e. no passengers for hire or reward, for insurance purposes, it's a motorhome, for registration purposes it's a motorhome.
Clear as mud eh

The prev signs going down the hill was ALL VEHICLES with xxx?? or more axles MUST use low gear and speed limit is 60kph (can't remember if it was 4,5 or 6 axles) but you get the drift.. I think they should put ALL heavy vehicles etc so much clearer.

5 axles it is, Dot.

There is a problem with light diesel trucks that have neither engine brake nor exhaust brake - particularly modern diesels with small but powerful engines. They have virtually no engine braking capacity, not as much as a petrol engine that has a carburetor butterfly that creates a vacuum within the intake manifold thereby adding to its braking capacity. The high compression factor against a rising piston is almost completely negated by the "spring" effect forcing the piston down even though there is no combustion. The "Jake" or compression brake overcomes this spring effect by releasing the compressed air directly into the exhaust manifold at the top of the piston stroke resulting in no force being applied to the downward stroke.

Very little is achieved by changing down a gear in a modern light (high speed - as they are sometimes known) diesel. Some additional friction is achieved but that is minimal. On the steeper grades such as the Mt. Barker freeway down into Adelaide, changing down a gear makes the engine spin faster with minimal braking effect. Even slowing the vehicle right down and engaging 3rd or 2nd gear of a 6 speed box can't do it without some assistance from the foot brake from time to time. To achieve an equilibrium the vehicle would be so slow as to present a danger to other vehicles travelling down the hill. In my case, the Fiat 3.0 litre at 5 tonne, about 80 kph down the Mt. Barker freeway is the speed at which the least amount of foot braking is required (other that in 1st gear at about 10 kph).

My argument does not seek to justify the use of the foot brake, but points out that some vehicles cannot safely get down the mountain without some judicious use of the foot brake. If I am making an argument for something, it is that vehicles of the type that cannot hold a safe speed down hills with engine resistance alone should be fitted with a suitable engine or exhaust brake. Of course it is not practicable to retrofit an engine brake but an exhaust brake can be fitted to almost any engine. And, you guessed it - there is currently no "off the shelf" unit for the Fiat. In answer to the comment that I anticipate, SGV won't sell me one because they don't know what the allowable back pressure for the Fiat is.

Comments welcome - unless you disagree with me

Thanks for that info Steve, 5 axles it was. I understood each and every word you wrote.hmmmm. I must admit to having to give the foot brake a tickle every now and again but nothing that would constitute them getting warm and anyway I had that big truck in front of me I am happy that I was able to pass a couple of trucks going back up the hill I reckon those extra cameras will be catching some of those cowboys out there. No excuses as the signage with the hills warnings starts way way back and the signs are very clear. Lets hope these accidents now stop.

another 6 since last post.. We must be popular then?

We do not have an exhaust brake on the swaggie, and with the auto, the potential for fun n games on hills is high. I lock down to a ratio that will allow me to maintain a safe speed, and keep an eye on the revs, if they start creeping too high, its a jolly good stabbing on the brakes till it behaves itself. Most times its only a couple of dabs required. I tend to start in a lower rge till I get a feel for what is happening.

I can see regenerative braking and take off/hill climb assist becoming more and more popular as a form of engine braking. Basically it's small electric motor either replacing the alternator, mounted to the front of the engine or mounted along the tail shaft for rear wheel drive heavier vehicles. eventually they will be built into the flywheel area during production doing away with the alternator and starter motor. This idea would work very well in a motorhome as the battery required could double as the house power supply or feed a DC to DC charger to top up the house batteries.
That is a project for big bus, I have the electric motor and controller, the battery bank will double as the house battery.

T1 Terry

Girt has a 6.5l turbo diesel with auto box. No Jake-Brake. We have disc brakes on all 4 corners.
When we're descending hills with a "Trucks Use Low Gear" sign at the top, we generally lock it into 2nd, as 1st can't be engaged while rolling. Even so, speed gradually builds, and a judicious application of foot-brake is required.
Still, it's better than barbecued disc-pads!