Ignition switches - safety

[G4XWD Jim]

In the many years that I have been driving I've had a few occasions where the throttle has jammed open or the carburettor return spring has broken resulting in the engine running away with itself. I've been able to stop it without too much drama with the ignition switch or in the case of a motorbike using the exhaust valve lifter. (old bikes) 

What would one do with a modern car that has a credit type card to make the ignition circuit live. I'm thinking particularly about electric cars with their high torque of which I know nothing. Can they go berserk, how many safety features do they have.

My Daughter in law had a Renault Espace which had a card and no ignition switch. As long as the card was near the car the ignition circuit lit up. Her little daughter dropped the card somewhere down the back of the dashboard, irretrievably and they couldn't stop the engine. Her husband managed eventually to sort it but what a fiddle.

Any thoughts

Jim

[Kalee20]

Dunno. But I once had a car where the throttle return spring broke, the pedal went straight to the floor and it started accelerating (gently - Morris Minor with 948cc engine).

All I had to do was switch off the ignition and coast to a stop. Then a rubber bungee, which luckily I had with me, did service for the rest of the journey.

Not being able to stop the engine, independently of steering lock, lights, brakes possibly, does worry me slightly - with an electrically-actuated handbrake, can you use it if the main hydraulic brakes fail, for instance?

[peter scott]

I would think that the brakes should be able to exceed the torque of any car engine or electric motor. By coincidence I am just finished reading a book in which the throttle connection of a light aircraft broke. When this happens a spring operates at the carburettor to open the throttle wide. The pilot then regains control by operating the ignition switch.

Peter

[Ed_Dinning]

Hi Folks, I think it comes down to the driver thinking and not panicking.
A few years ago there was the case of a driver who claimed that his car ran away with throttle fully open (petrol not diesel where it can happen). He controlled the car on the brakes until he boiled the brake fluid as he was worried the steering would lock (no the accessory position stops the engine but does not engage the steering lock until in the fully off position and /or key removed).
I don't think to police believed him either as he was prosecuted.
In most modern cars there are twin circuit brakes, so diagonal operation is possible and even without servo assistance the cars should be capable of being stopped
In the Ford system power is still available to the handbrake motor even with the key out, so if you walk away and then remember you need to set the handbrake it cam be done without inserting the key.
Stopping with only this sort of braking may be a bit "interesting" as the rear pistons are then wound in to the rear discs

I believe that the road traffic acts specify that the braking system must be able to overcome the engine power.

It was a well known technique in early aircraft to "blip" the ignition switches on approach to landing to reduce engine revs as the throttle systems on early aircraft were more like an on/off control

As ever on a car the weakest component that causes all the failures is the nut that holds the steering wheel

Ed

[Richard_FM]

I heard of a lorry speeding on a motorway about 20 years ago & claiming the throttle had stuck.

I did wonder if it was possible if this happens to push the clutch in & shift into neutral.

Another option would be to gently put the hand break on, but as it only operatives on the rear wheels this might be risky.

[Amie]

Heavy goods vehicles have air brakes and the "hand" brake acts on all wheels?

Thanks,
Amie.

[Nick]

On landrovers the handbrake is a transmission brake on the back of the transfer box, not on any wheel.

When working on them you have to chock the wheels.

[Murphyv310]

There was an issue in the 90's with a US Ford pick up that had a fault in very hot conditions. The engine ECU developed a power supply issue that in rare cases would make the engine run at full pelt. Switching off the ignition didn't work and you were not able to shift into neutral. I believe there were either two or three people killed. Ford's answer was the lawsuit was cheaper than a recall and new electronics to the vehicles. What happened after in court I don't know.
Snag is I cannot remember what actual model it was but if I do find it I'll post it up. This was from a report on TV about 15 years ago.

[Kalee20]

I did have an issue years ago, driving my boss's Jaguar Automatic, where I switched off the ignition, on the move.

What happened was, and it was after dark, lights of a big vehicle were coming towards me, on a bend, fairly narrow road. I braked slightly. But as I moved my foot from accelerator to brake, my knee caught the huge fob dangling from ignition key (on right-hand side of steering column) and flicked it off.

Immediately, headlights went out - safety feature to stop main lights being left on without engine running, and flattening battery. And the engine of course started to run down.

Steering got heavy, as power assistance was lost. No matter, switch ignition back on. Headlights back on.

But by this time, engine had come to a rest (it was an automatic) so it didn't pick up and without engine running and driving the steering hydraulics,
steering remained heavy. Turn switch to 'start' position. But apart from the lights going off again (again, feature to reduce load on battery while cranking engine), nothing happened - because the gear selector was not in 'Park' or 'Neutral'. Release - lights back on again.

No matter, shift to neutral. Try and start again. But, key won't turn (another safety feature, to prevent turning wrong way and engaging starter motor on an already-running engine).

Switch off ignition. Lights off. Switch on, lights on. Turn to 'Start', this time everything is right, engine starts. Lights back on, and steering suddenly goes light again.

Move transmission lever back to 'Drive', and carry on.

And all this when negotiating a bend, with a big vehicle oncoming, no doubt wondering about the on-off-on-off-on-off-on-off-on of my headlights...

[chriswood]

All the recent cars I had or rented without conventional keys have multiple safety systems to avoid the position where throttle can jam open or run away. Most throttles on new cars are drive by wire there is no linkage, the only things which are still direct ie not controlled by the onboard computers are the foot brake and steering which have power assistance so if the car is maintained you should always be able to stop and steer. So they seem pretty fool proof, that is not to say  without problems as several times cars have needed software updates to fix problems. It is also possible a manufacturer will do what Boeing did with MCAS and inadvertently design a system which causes a crash.