Auto trans question

Having sold my 09 OR/AC V6 6sp man, I will pick up the new '13 V6 S/DCSB 5sp auto tomorrow.
I have never owned an auto trans and need a bit of education.

What is "torque converter" ; is it possible to tell, perhaps on tach, when it locks and unlocks, as opposed to a shift to next lower gear ?

What about cruise when coming to a hill; back off 5 and stay in 5th or anticipate the shift and move to 4 ahead of the computer to prevent losing the momentum and going down 2 gears for a short time. This is most likely a personal preference thing, and is certainly dependent on the hill, but am just curious what other folks think.

Thanks, Roger

 

A simplified explanation:

The torque converter in an automatic transmission basically takes the place of the clutch/pressure plate's job for a manual. It is the mechanical connection between the engine and the transmission. The Torque converter lockup is when the internal parts of the torque converter are "locked" together. This improves fuel economy, and reduces heat.

You can tell on your tach if it is locked up, but first you will need to drive it and get used to the shift points and know what gear yo uare in. traditionally a torque converter will not lock up under speeds of 45 mph, or when engine load is higher than 10%.