What’s the point in the Park function of a automatic?

[Nickbrapp]

I was thinking today, manual cars have neutral, which most people use when they park, and the parking brake,

So why does an auto have park, neutral and parking brake?

You always see on tv especially in American programs they only use the transmission park, so why do we have both?

[EmailAddress]

We have hills.

[TonyRPH]

A manual left in gear will offer some roll resistance because the clutch is engaged and the engine compression will resist rolling to some degree.

An automatic left in gear has no clutch to engage, so can't offer any rolling resistance from the engine.

Hence the 'Park' facility, which engages a pawl in the gearbox to prevent the output shaft turning.

[sooty61]

I would say most people use P when they park. I never use the handbrake

[ScoobyChris]

sooty61 said:

I would say most people use P when they park. I never use the handbrake

In my car it engages P when the engine gets switched off anyway but I use the handbrake also. In manual cars, I’ll always leave it in gear with handbrake on.

Chris

Edited by ScoobyChris on Saturday 18th March 21:51

[MDMA .]

If you didn’t have park, you couldn’t take your keys out the ignition

[Nickbrapp]

MDMA . said:

If you didn’t have park, you couldn’t take your keys out the ignition

But why do we have park

Why not leave an auto in neutral and use the parking brake the same as manual cars?

[Silvanus]

MDMA . said:

If you didn’t have park, you couldn’t take your keys out the ignition

Not many modern cars have an ignition key. My work auto doesn't.

[TonyRPH]

Nickbrapp said:

But why do we have park

See my post above - it's to provide additional assurance in addition to the handbrake - just like leaving a manual car in gear.

[joropug]

Nickbrapp said:

But why do we have park

Why not leave an auto in neutral and use the parking brake the same as manual cars?

I guess the better question is why don’t manuals have park function.

In a manual I always leave in gear, on a flat I never used the handbrake (BMWs mostly that had awful handbrakes anyway)

In my torque converter auto I use the handbrake only if it’s going to roll back or forward, to take the pressure off.

Our DCT automatic however does park and handbrake simultaneously when you turn the engine off.

[samoht]

One of my cars has a dual clutch with no Park function at all, so you just put it into Neutral and then rely on the handbrake to secure the car. So that's a bit like what OP is saying.

I imagine that when torque converter autos first came out, handbrakes were less reliable than they are now and so leaving the car 'in gear' was more common, and so the autos needed some equivalent function to back up the handbrake.


Personally I prefer the way Nissan EVs work, if you brake it to a stop on the footbrake then the car will stay put until you explicitly request it to move, regardless of slope. Like, how often do you want a car to start rolling away?? So make it do the sensible thing by default.

[Wacky Racer]

You should never leave a manual car parked up in neutral.

Always in first, plus apply the handbrake....No chance of the car rolling away.

[Dogwatch]

Wacky Racer said:

You should never leave a manual car parked up in neutral.

Always in first, plus apply the handbrake....No chance of the car rolling away.

[Higgs boson]

Wacky Racer said:

You should never leave a manual car parked up in neutral.

Always in first, plus apply the handbrake....No chance of the car rolling away.

If I'm facing downhill, I stick it in reverse. You likely do, too.

[stevemcs]

We see quite a few automatic cars fail there mot because the owner never uses the handbrake, personally I always use the handbrake

[Cliftonite]

Wacky Racer said:

You should never leave a manual car parked up in neutral.

Always in first, plus apply the handbrake....No chance of the car rolling away.

Seems this is too complex for the majority of drivers to fathom?

Why take the risk of a failed (or forgotten) handbrake when leaving a car in first (or reverse) gear is such a simple and effective way of nullifying it?

In a similar vein, using the handbrake in an automatic relives pressure on the gearbox pawl and reduces the risk of damage, e.g. when parked on a slope or if a collision occurs.

[Second Best]

Cliftonite said:

Seems this is too complex for the majority of drivers to fathom?

Why take the risk of a failed (or forgotten) handbrake when leaving a car in first (or reverse) gear is such a simple and effective way of nullifying it?

In a similar vein, using the handbrake in an automatic relives pressure on the gearbox pawl and reduces the risk of damage, e.g. when parked on a slope or if a collision occurs.

When I learned to drive (in the late 2000s) I was taught handbrake and neutral, unless you're parked on a steep incline. Most of my non-petrolhead friends also leave their car in neutral when parked, sometimes it's caught them out when we've driven each other's cars and they've started it without checking if it's in gear. I find it funnier than they do.

Does anybody else here have an EV with a manual handbrake? I didn't think EVs were able to have a "Park" setting, so to speak, indeed mine just has R/N/D. Disengage the handbrake and you can push it around.

[cootuk]

At least you don't have air brakes to worry about. We don't leave wagons stood long term in gear as, if they lose air pressure, you will find yourself trying to start it in gear until you can jolt it back to neutral.

[Ninja59]

Modern automatic you pretty much cannot leave one or the other off. They both go on when the engine turns off.

But like a manual you can leave it in gear like am extra form of protection against rolling away.

[ATG]

I don't trust the gearbox or the handbrake, so I chock the wheels and use an anchor or chain my car to a convenient piece of street furniture like a lollipop person or someone praying outside the VD clinic.