Hi,
It is my first car with automatic gear, so sorry for a diletant question.[:I]
What is going when the gear is on "parking"? Is it rigid connection between gear and wheels in this position?
Is it necessary to use arm brake at "parking" position of gear?
Is any demage caused if no?[?]
Thanks ahead.
Automatic gear-need explanation
Moderator: RichardW
Mark,
Simplest explanation is that the "park" position on any auto transmission is effectively working on the same principle as a flywheel or cog with a solid pin being jammed in between a couple of the teeth. It jams it solid.
As autos take the power from the engine via a fluid coupling or torque converter as it is called, there is no direct mechanical connection between these two major components, hence the park mechanism.
It is always adviseable to also use the hand brake for several reasons such as to act as a back up for the park mechanism in case it doesn't quite snap into position and suddenly starts to roll forward whereupon they can sound like a ratchet unless they suddenly catch & then usually start breaking things and also to take some of the strain off it due to the inclination of the mechanism to hold the weight of the car. The result of this can be that when you return to your car, it will start OK but when you go to select a gear, the lever will just flop around as though it's not connected to anything and no gears will select, obviously due to the spigots jamming on the cog. Whilst this used to happen on earlier model autos (early Borg Warners, Torque flight & Toyoglide boxes in particular) I haven't heard of it in more recent times although I can see no reason why this would not apply. The biggest nono of all, is to put into park with the car in any type of motion as this can easily lead to terminal damage.
Alan S
Simplest explanation is that the "park" position on any auto transmission is effectively working on the same principle as a flywheel or cog with a solid pin being jammed in between a couple of the teeth. It jams it solid.
As autos take the power from the engine via a fluid coupling or torque converter as it is called, there is no direct mechanical connection between these two major components, hence the park mechanism.
It is always adviseable to also use the hand brake for several reasons such as to act as a back up for the park mechanism in case it doesn't quite snap into position and suddenly starts to roll forward whereupon they can sound like a ratchet unless they suddenly catch & then usually start breaking things and also to take some of the strain off it due to the inclination of the mechanism to hold the weight of the car. The result of this can be that when you return to your car, it will start OK but when you go to select a gear, the lever will just flop around as though it's not connected to anything and no gears will select, obviously due to the spigots jamming on the cog. Whilst this used to happen on earlier model autos (early Borg Warners, Torque flight & Toyoglide boxes in particular) I haven't heard of it in more recent times although I can see no reason why this would not apply. The biggest nono of all, is to put into park with the car in any type of motion as this can easily lead to terminal damage.
Alan S
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Dave Burns
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The gear that locks the transmition is called the sprag wheel, the teeth on it are virtualy square cut to prevent the locking pawl being forced out under load.
On expensive cars the park feature is engaged and released hydraulicly, making gear selection from this position easey, on cheaper cars the lever may need a slight tug to release it from the park position if the sprag wheel is loaded.
Dave
On expensive cars the park feature is engaged and released hydraulicly, making gear selection from this position easey, on cheaper cars the lever may need a slight tug to release it from the park position if the sprag wheel is loaded.
Dave