Auto Transmission Problem

[luckey007]

AFAIK an AT vehicle should behave like in Neutral when I take off the foot from the accelerator. But in my car-CE110- when it is in OD when I take the foot back I feel engine brake like thing. It doesn't happen in other gears.Friends, is this normal or something wrong with it.

Please help guys.

Thanks in advance.

[VVTi]

An Auto behaves in the manner you mention when you take the foot off the pedal. As soon as you do that, the engine braking begins.

Whether OD is on or not, it really does not matter,. The moment you take the foot of the gas, the car will slow down and not go to this 'neutral' that you assume it does.

How can it be in Neutral when its in gear? And the CE110 is a diesel engine powered car, hence you will have a more profound affect due to the torque of the diesel.

[luckey007]

An Auto behaves in the manner you mention when you take the foot off the pedal. As soon as you do that, the engine braking begins.

Whether OD is on or not, it really does not matter,. The moment you take the foot of the gas, the car will slow down and not go to this 'neutral' that you assume it does.

How can it be in Neutral when its in gear? And the CE110 is a diesel engine powered car, hence you will have a more profound affect due to the torque of the diesel.

Thanks a lot for the quick reply.

These are the reasons for my assumption.

1.In AT the power is transferred via a torque converter, not by a clutch.

2.In this forum also it is said that brake wear is more in AT vehicles due to the absence of engine brake.

3.And why is it advised to not to go in a steep slope in D position.

4.If there is engine break-That means the rotational power of the wheels can be transferred to the engine- why can't we start an AT vehicle by pushing?

And dear friend I did not mean the exact neutral position. I wanted to say was it "behaves" like until you press the gas. Just like when you riding a push bike in a slope it gets your power you only paddle faster than the bikes speed and you can't stop bike simply slowing the paddling speed.

Please clarify my doubts. Thanks.

Edited August 4, 2011 by luckey007

[VVTi]

Thanks a lot for the quick reply.

These are the reasons for my assumption.

1.In AT the power is transferred via a torque converter, not by a clutch.

2.In this forum also it is said that brake wear is more in AT vehicles due to the absence of engine brake.

3.And why is it advised to not to go in a steep slope in D position.

4.If there is engine break-That means the rotational power of the wheels can be transferred to the engine- why can't we start an AT vehicle by pushing?

And dear friend I did not mean the exact neutral position. I wanted to say was it "behaves" like until you press the gas. Just like when you riding a push bike in a slope it gets your power you only paddle faster than the bikes speed and you can't stop bike simply slowing the paddling speed.

Please clarify my doubts. Thanks.

1. Correct

2. That's becasue in an AT when you apply the brakes the engine is still driving the wheels and hence the brake force required is higher. In a MT, many if not all drivers press the clutch while braking, (unless in an emergency) thereby reducing the load on the wheels, thus reducing the brake force needed.

3. I am not sure what this means. Normal driving D is the best option. But then if you are coming down a steep slope, many choose 3 2 or L to give the additional engine breaking required to slow down, else on D the car will pick up speed and while the gears change up. This will require bigger braking forces and sometimes depending on your skill levels, leaving skid marks on your tighty whiteys... Especially coming from from NE....

4. This is the simplest of all theories. AT works on hydraulic pressure powered by the engine rotating the TC. So without the required hydraulic pressure to turn the GB, how does one start a AT car by pushing. There is no physical link, Only a fluid link.

A MT has a physical link, making it easy for a push start.

[VVTi]

machang, also, riding a bike with a free wheeling hub and driving a car with an AT are 2 different things... do not mix the two up.

[toyota sucks]

Thanks a lot for the quick reply.

These are the reasons for my assumption.

1.In AT the power is transferred via a torque converter, not by a clutch.

2.In this forum also it is said that brake wear is more in AT vehicles due to the absence of engine brake.

3.And why is it advised to not to go in a steep slope in D position.

4.If there is engine break-That means the rotational power of the wheels can be transferred to the engine- why can't we start an AT vehicle by pushing?

And dear friend I did not mean the exact neutral position. I wanted to say was it "behaves" like until you press the gas. Just like when you riding a push bike in a slope it gets your power you only paddle faster than the bikes speed and you can't stop bike simply slowing the paddling speed.

Please clarify my doubts. Thanks.

Specially how can a person push start a auto as when to connect it to the engine it must be in D and it dosen't start in D

So there is no useful push start options in autos except the useless push start

[The Don]

1. Correct

2. That's becasue in an AT when you apply the brakes the engine is still driving the wheels and hence the brake force required is higher. In a MT, many if not all drivers press the clutch while braking, (unless in an emergency) thereby reducing the load on the wheels, thus reducing the brake force needed.

3. I am not sure what this means. Normal driving D is the best option. But then if you are coming down a steep slope, many choose 3 2 or L to give the additional engine breaking required to slow down, else on D the car will pick up speed and while the gears change up. This will require bigger braking forces and sometimes depending on your skill levels, leaving skid marks on your tighty whiteys... Especially coming from from NE....

4. This is the simplest of all theories. AT works on hydraulic pressure powered by the engine rotating the TC. So without the required hydraulic pressure to turn the GB, how does one start a AT car by pushing. There is no physical link, Only a fluid link.

A MT has a physical link, making it easy for a push start.

VVTI, I'm not sure if your point #2 is correct. Most drivers clutch at the last minute or go to a lower gear and re engage to slow the car down. While I do not doubt there is some engine resistance felt through when the accelerator is disengaged, it is certainly not as profound as a manual in a lower gear.

Do you think what is happening here is that the automatic transmission is shifting down when the accelerator is disengaged and the driver will feel the resistance provided by the engine ?

[luckey007]

machang, also, riding a bike with a free wheeling hub and driving a car with an AT are 2 different things... do not mix the two up.

I thought the TC transfers power to only one direction.-just like free wheel-

[toyota sucks]

VVTI, I'm not sure if your point #2 is correct. Most drivers clutch at the last minute or go to a lower gear and re engage to slow the car down. While I do not doubt there is some engine resistance felt through when the accelerator is disengaged, it is certainly not as profound as a manual in a lower gear.

Do you think what is happening here is that the automatic transmission is shifting down when the accelerator is disengaged and the driver will feel the resistance provided by the engine ?

engine breaking happens only in 1 and 2 gears,

it doesn't happen in D

if this happens or delays to become free rolling it's a defect of the gearbox

[leyland]

Apparently only petrol (gasoline) engines provide engine breaking in the true sense of the word. Lite-duty diesels do not have engine breaking it seems unless the engine has been specifically designed to provide engine breaking. See the wiki entry @ http://en.wikipedia.org/wiki/Engine_braking - Didn't know about this until I searched the web. Also I don't think most diesel vehicles in SL including lorries & buses (especially those Tata's and Leyland's) have engine breaking either since I have not heard the unique (IMO awesome) sound those large diesels produce during engine breaking here in SL. I remember signs on some road sections close to residential areas in Aus specifically prohibiting engine breaking during the night.

[luckey007]

engine breaking happens only in 1 and 2 gears,

it doesn't happen in D

if this happens or delays to become free rolling it's a defect of the gearbox

My problem is it doesn't free roll in OD and does free rolling in other gears when the gear liver is in D.

Edited August 5, 2011 by luckey007

[Kavvz]

Apparently only petrol (gasoline) engines provide engine breaking in the true sense of the word. Lite-duty diesels do not have engine breaking it seems unless the engine has been specifically designed to provide engine breaking. See the wiki entry @ http://en.wikipedia.org/wiki/Engine_braking - Didn't know about this until I searched the web. Also I don't think most diesel vehicles in SL including lorries & buses (especially those Tata's and Leyland's) have engine breaking either since I have not heard the unique (IMO awesome) sound those large diesels produce during engine breaking here in SL. I remember signs on some road sections close to residential areas in Aus specifically prohibiting engine breaking during the night.

They do. Buses make quite a racket when its engaged, and you can frequently hear drivers engine braking before taking a bend or as they ride your bumper whilst awaiting an opportunity to hurtle head on into the path of unsuspecting traffic. On Tata diesels the engine brake is activated via a small plasticky pedal located near the driver's seat; set away from the other pedals and located such, so as to be depressed by the driver's left heel rather than the ball of the foot.

[Sylvi]

They do. Buses make quite a racket when its engaged, and you can frequently hear drivers engine braking before taking a bend or as they ride your bumper whilst awaiting an opportunity to hurtle head on into the path of unsuspecting traffic. On Tata diesels the engine brake is activated via a small plasticky pedal located near the driver's seat; set away from the other pedals and located such, so as to be depressed by the driver's left heel rather than the ball of the foot.

'Kavvz',

Engine brake what you mention it blocks the exhaust gases coming out from the engine. As the gas peddle is not operated at that time no power is produced from the diesel engine.

When the exhaust brake is operated The engine is still working then the pressure is build up due to closer of the exhaust system and the Vehicle speed comes down this is mostly is used by hill country drivers to control the speed of the vehicle when they drive on down hill.

Sylvi Wijesinghe.