Say your accelerator jammed

Sure, the Steering on my MX-5 can't be much more than 2 turns lock to lock. Without assistance the wheel still turns though, and at motorway speeds failure of the assistance would be noticeable but the car would still be eminently steerable.

Parking would need some fairly serious effort.

Why don't the government do something!

Yeah but, how about an automatic? If the throttle is jammed open then I imagine as the vehicle speed drops, the box is going to react as if you've hit a fecking big hill and start dropping cogs.

Could you stop a car at full throttle in first gear say? Add the possible effect of reducing servo assistance with a wide open throttle and brake fade (which I think could come on very quickly in those circumstances) it might well not be possible to stop a full throttle auto with the brakes alone.

Does anyone know if there are any autos that *can't* be forced into neutral whilst under load? Evidently some owners are under the impression that this can't be done.

Tim

Indeed - you get valve 'float' on most which limits the maximum revs.

Yes.

I'd say it still would on one with half decent brakes.

Don't know of any. My BMW has a computer controlled auto and you can on that.

I bought an 8v Punto, and there's really no question of it needing a rev limiter. Just as well, considering what the kids do to it.

If you leave it in gear & turn the ignition off you won't lose either. Even if you do the you won't lose the servo unless you pump the brakes.

Duncan Wood

But unless you pump the brakes you won't loose the servo assist. If you turn the engine off the pedal doesn't rise up under your foot.

Douglas Payne expressed precisely :

If the pedal is pressed and kept pressed, it will use up a minimal amount of vacuum. However repeatedly pressing and releasing could use up all of the vacuum. Test it - climb in the car and without starting it press the brake several times. Assuming there is no fault in the servo, you should be able to press it four of five times before the vacuum is exhausted.

One of the suggestions is to knock it out of gear - that cannot usually be done when the car is accelerating or decelerating, unless the clutch is pressed. Pressure on the gears keeps it in gear.

Tim laid this down on his screen :

I checked this out for a completely unconnected reason about twelve months ago on my auto and yes I can most certainly bring it to a stop from in excess of 70mph.

David Taylor used his keyboard to write :

Or too busy making phone calls - why would a busy and panicking driver with a car full of perfectly capable passengers, make the call and commentary?

When they built electric trains in the 60-70's, the failsafe was a long electrical wire that ran right down the train, looped through various emergency stop handles and other interlocks and required a flowing current to hold a contactor *in* to maintain motive power, and another contactor to allow the brakes to be let off.

If the wire broke or the current interrupted, motors off, brakes on emergency application...

They *thought* about basic s*it like this back then.

I worry about SWMBO's MINI (stupid start button) buy at least that has a mechanical clutch and a plain box.

But I am starting to think that they really need an emergency pull knob that guarantees to disengage the engine at a very low and simple level like cut off power to the injector pump and ECU and spark assembly where applicable and cut the fuel on a diesel.

How many still use vacuum servos?

Be very easy to disable the fuel pump on a petrol engine - but the engine wouldn't stop instantly due to the pressure left in the rail.

Nearly all.

Dave Plowman (News) has brought this to us :

Both of mine do.

Dave Plowman (News) wrote on 06/02/2010 :

It would be even easier to cut off the ignition on a petrol and an instant stop would result.

or depress the clutch or select neutral.

Seems not with keyless ignition. And trying to interrupt the ignition circuit with an additional switch of some kind could prove tricky. The fuel pump less so.

Remember that story in the news ages ago. A lad in a BMW called 999 as the accelerator was stuck, and the car was going over 100mph an accelerating. The conversation was played in the news, I think. He was adviced not to switch ignition key off as that would lock the steering wheel. The story seemed quite implausible at the time and there was a lot of ng discussion. The lad sounded too much like a dash for fame methinks. Possibly someone here can still dig it up?