Re: No brakes? - Range Rover
>> ..as the handbrake acts on a separate disk on the back of the gearbox...
> The seperate transmission brake on Land Rover vehicles is actually a drum brake.
Actually, I believe most (all ?) of the new models no longer have this. DIscovery 3/4 have parking brakes which are a set of shoes that work inside a drum which is part of the disk hub - and applied electrically. My mate tells me they change a lot of the actuator assemblies when they seize up.
And in any case, if you do have a transmission brake, then you really do not want to be trying to use it at speed. I know people that have ripped the backplate off the gearbox, and if that doesn't happen, there's still the propshaft, diff, and driveshafts to let go. The transmission brake is usually not very smooth either - so you'd be applying not just the braking effort, but a lot of cyclic variation (ie vibration and shock) to the rear axle etc.
As to the "you can always turn it off" brigade. In theory you can, but if there's a computer/electronics fault then there is never any guarantee that "press and hold the start button" will actually turn off the engine. The only (almost) guaranteed method is to have a physical switch that will physically remove power to some required service (fuel supply or ignition).
Also, as pointed out, we don't know the extent of the driver's disability, and whether he would have been capable of taking a hand of the controls to press and hold a button for long enough to kill the engine.
As an aside, when the 'first' 'new' Range Rover (P38) came out, there were a couple of reports of people careering down hills, in neutral, with no brakes. Nothing wrong could ever be found, and there was never any proof either way - Land Rover never accepted any problem existed. It is thought the process went like :
Attempting steep/slippery hill. Fail with wheels spinning. Apply brakes and attempt to engage reverse. Car rolls backwards at speed.
The theory was that the spinning wheels confused the ABS into thinking it was skidding and so it took the brakes off to correct the skid - allowing the car to roll back down the hill. Meanwhile, the "fly by wire" gearbox refuses to engage reverse while the vehicle is moving. So no brakes, in neutral, on a hill steep enough that you failed to get up it.
I've seen how fast a vehicle can pick up speed on such hills. "Exciting" probably doesn't do justice to the experience !