What is the specific purpose of this on automatic transmissions? Does it serve more than one purpose?
They allow you to run in first (L) and then 2nd gear (2) without the transmission shifiting into a higher gear. This is good for say, snowy conditions.
“Low” and “2[SUP]nd[/SUP]” gears. They give you more power for hauling and getting out of mud or snow, but they’re not for use when driving at high speeds.
Hope this helps.
Adam
There also handy for driving your car up and down the Mount Washington Auto Road in New Hampshire. It keeps you from frying your brakes.
Yep if you check your owners manual it will show you the max speeds for the L and 2 gears for your particular car. You want to make sure you do not take it past the redline in these gears because you can cause some major damage.
Sometimes an automatic will ‘hunt’ (IE switch back and forth between two gears) for the right gear in certain situations, by using L or 2 you can prevent this from happening. For example when climbing a hill the transmission will switch from 2 to 3 but not have enough power to climb in 3, so drops back to 2 and so on.
It also allows you to hold a lower gear if you expect to have to accelerate quickly while you are already moving. Normally when you try to to accelerate quickly in an automatic there is a short delay while the transmission downshifts.
Also, here is a similar thread on this topic.
You will rarely use them but it’s good to have the option to do so “just-in-case”. As another poster indicated, read your owner’s manual.
Even if you never use them it’s better to build the car with the option than without.