Declutch in Automobiles

The problem is present in most.
Continuously variable transmissions don't have this problem.
The clue is in the name 'Automatic'... the gearchange is automated presumably including measures to de-clutch/dissengage/match revs etc. E.G using a fluid flywheel/clutch, or on motorbikes a centrifugal clutch.
They are set up to creep when in drive so they don't roll backwards.
In a manual bow you simply have to learn to do the same, use the clutch to creep.
Maybe beginers should buy/learn in automatics...
Del

Part of the UK driving test in a manual shift vehicle is the "hill start", which involves demonstrating pulling away on a rising grade under full control of the clutch, accelerator and handbrake simultaneously without the vehicle running backwards. This skill must be acquired before a full driving licence can be issued, among many other skills.

At what point did it become a problem?

I becomes a problem when the vehicles are there waiting in a row in signal and usually there is tendency not to maintain the minimum distance betweeen the two vehicles. If your vehicle roll back u hit the person behind. Its really a problem for beginners. What idea can be thought to overcome this. any suggestions???

Tighter standards for the Driving Test!

You could put the handbrake on - that will stop you rolling backward or forward.

This is exactly what you would do in a manual transmission model.

That's right, if the hill is fairly steep the creep effect doesn't stop the car rolling back. I agree handbrake is the right method, but I've known auto drivers who don't bother, but use the footbrake, easy enough with 2 pedals. Hard luck on drivers behind, at night or in rain, who get the brake lights in their eyes.

Having said that, there's also plenty of manual drivers who don't seem to know they have a handbrake. Lazy and inconsiderate driving, in my opinion.

Codey

That's why having third party insurance cover, as a minimum, is mandatory when using a motorised vehicle on the UK's roads.

Where is this thread going, please? A hill-start is approaching...

Got to agree....if someone can't do that, they need more training to drive. They haven't yet learned the needed coordination to drive a stick shift. The handbrake trick works on some cars....but not all depending on the exact configuration of the emergency brake and release mechanism. The best for that was on an old AMC I once owned, you set and released it with your left hand. The ones with the center console Emergency brake are just as easy. The ones that set with your foot but release by hand are too abrupt.

But as others have said....its an indication someone needs more training to drive, and should practice it more at times when there isn't much traffic. Its not a hard skill to learn, but it does take practice. But like riding a bicycle. you never forget and pick it back up even after years of driving an automatic.

When I got my liscense at 16, that was part of the test if you showed up in a stickshift. But wasn't manditory if you showed up in an automatic. We tested in your own car, whatever it was.

I drive both regularly. There really isn't a reason to drift back at all or smoke the clutch through excessive slippage even on the steepest hills I have encountered.

Exactly. When driving a stickshift and stopped on steep hills I've applied the handbrake to help hold the car while keeping one foot on the gas and the other on the clutch. On shallow hills, careful balancing between gas and clutch keeps the car from rolling backward. In either case, just a bit of practice allows smooth forward motion without rolling backwards once the traffic in front begins moving again. You need to make sure you've downshifted into first gear when you come to a stop.

Before I learned how to coordinate clutch and brake at steep inclines, I used the handbrake to stay idle, then when the signal turned green, I slowly released the clutch while pumping a little more gas, and when I felt the slight pull on the vehicle, I released the handbrake and moved up-hill with ease.

Anyhow, it looks unevitable to pay someone for damages at certain point in your life, you can dramatically reduce this by practicing on lonely streets.

Don't be too shy, don't be too bald, just be yourself and enjoy the ride.

Studebaker introduced what you are looking for in 1936. Called hill holder.

Subaru presently offers them on their manual transmission vehicles. Some of the automakers have them too.

Why the problem of declutching is not present in Auto transmission vehicles compared with manual transmission vehicles?

That's why the call it automatic transmission. The clutching is being done for you by a series of clutch packs one for each gear. Pressure is being applied by hydraulics to the packs. A control valve controls the shifting it use to be off engine vacuum, electronic have taken over on most vehicles there.

Not to long ago, I seen a woman freeze in a brand new Subaru that had hill hold at the corner of Divisadero St/ Union St in San Francisco. She was headed up hill on the South bound side and had over 4 blocks of traffic behind her waiting Never did find out what happen, as I was headed the other direction going down hill and could not stop

I changed to a Subaru Forester a couple of months ago & the hill hold device is great. On a hill you engage 1st gear & apply the foot brake then you can release the brake & the car maintains the brake pressure without needing the hand brake. The brakes release as the clutch pedal comes up to the bite point.

Sometimes, simple answers are best!

Unfortunately, automobiles are complex machines. The OP obviously has little or no working knowledge of automotive systems.

If you think the driving test for normal passenger cars is too hard try doing the full class A commercial licence test needed to drive a semi rig!

Personally I think the basic driving test should be as hard or harder than the class a CDL test. We all have far to many clueless idiots on the road as is. It would not bother me one bit to see about 25 % of the population knocked back to public transportation myself.

I once had a 1947 Pontiac with a hill holder. When you depressed the clutch it would engage a check valve in the brake line. You could step on the brake and it would stay engaged until you released the clutch. You could do the smoothest uphill starts with it.

When I was driving my pickup truck I would engage the emergency brake and release it simultaneously with the clutch.

However in later model cars the parking brake system is a set of cables that engages the rear brakes rather than a separate brake on the transmission. These only prevent a car from rolling forward but not backward as I discovered when trying to park my '64 Ford van on the raised berm at a drive-in movie. It kept rolling backwards. So I kept a block under the seat and would lean out and chock the wheel before taking my foot off the brake.

Nowadays I'm driving an automatic and if I know I'm going to be waiting a long time at a light I'll put it in park and rest my foot until the light changes.

automatic transmission clutch packs are hydrualicly engauged by a pump that's connected dirrectly to the output shaft of the engine, so the cluches are always under pressue determined by the rpms of the idling engine. the cluch of a manual transmission totally dis-engauges the trammission from the engine. one foot on the brake pedal and the other on the gas. it's takes practice.

Another GA from me K_Fry, your answers left me with nothing to add. As you said the 'Torque Converter', (a fluid coupling), is the correct answer to the OP's question. Good Job!

Thanks. I wonder what happened with the woman and Suburu. I wouldn't be surprised if she thought the car was "stuck" and never engaged the clutch enough to release the brake. Of course the adjustment could be off -- on my old Suburu, the system was adjustable, and cable actuated, if I recall.

Another possible problem for her would be trying to drift back into a parking spot (on a hill), which people do without thinking about it: you don't put the car in reverse and engage the clutch, etc. So if she was in first gear, with the clutch to the floor, and took her foot off the brake to allow the car to drift back, she'd be disappointed.

Wrong. The clutches in an automatic are either applied, and locked up, or released. No designed slippage. The clutches are fully applied as quickly as possible. There may be some designed in slowness just to soften the harshness of the shifts. but this is only fractions of a second.

At least in the USA, mechanics often don't know how to correctly set up a manual transmission car. The handbrake is neglected, but it is critical to starting on a hill (most car pedals aren't set up for heel-and-toe working of the brake and accelerator pedals, like all trucks used to be). Clutch travel is often set incorrectly. I'm not sure when I learned the correct technique for starting on a hill, but it wasn't from my instructor, and hill starting technique was not tested when I got my license. This would have been 1970 or so, so the problem is not new. Here in the Philippines, where most vehicles are manual shift but handbrakes mostly don't work properly (drivers parking on a slope usually chock their wheels), it is alternately comical and frightening to watch people starting on a slope. The smell of burnt clutch disks wafts on the tropical breeze. I stay well back, then enjoy the look on people's faces when it's my turn and I don't slide back one inch. THAT's how it's done.

Here in the Philippines, where most vehicles are manual shift but handbrakes mostly don't work properly. Sounds to me like some education is required.

Years back (in UK) when brakes were manually adjusted, some DIY-ers would wait till there was a problem before doing anything. The first problem would be handbrake failing, as the handbrake actuator has less travel than the service brake cylinder (the footbrake pedal was nearer the floor, but he wasn't bothered about that as long as it still worked). So he would think - handbrake problem, obviously I need to adjust the handbrake cable. This didn't cure the handbrake but improved the footbrake travel. Specially in the early Minis as the handbrake cable adjust nuts (2 separate cables) were inside the car at the handbrake lever, and drivers couldn't resist fiddling with them.

If the various adjustments are suspect, best to disconnect the handbrake cable and make sure it is pulled right back in the off direction at the wheels. Then do the shoe adjustment in the usual way. Then reconnect the handbrake cable (lengthen it first if necessary) and adjust till it is just about to apply the brakes.

But I'd have thought mechanics would know how to do it properly, maybe in the Philippines most people DIY?

Codey

Some Chrysler products in the early 50s had fluid coupling between the clutch and the engine. You could leave it in gear on a hill and do a smooth takeoff.