Cat vs Powerstroke torque curves

transamz9 wrote:
I have a stupid question for all the mathematicians on here. Everyone always says that torque is not work it's a force. Answer me this. If you ran out of HP on a slope and stalled out and stop you are now not making any hp correct? So now no work is being achieved because now you have torque applied to hold you from rolling backwards but no RPM are being achieved. Now reduce the applied torque just enough to allow you to roll backwards but still keep torque applied. Now you have RPMS, how do you measure how much hp it takes to hold a certain speed going backwards down the hill?

Trick question?

It doesn't take HP to hold a certain speed while rolling backward. You have to "use up" the power. Ignoring friction and wind resistance, you have to consume the same HP as going forward at the same speed would have taken. This power is used to make heat in your torque converter much Iike it would make heat if you used brakes instead. Now you do also need to apply some power from the engine to hold back. The is same amount that is normally wasted as heat just to lock up the converter.

If you include friction, some power is lost as heat in both directions so the "hold back" dissipated HP is lower than the climbing provided HP.

Think of it another way: Consider a long tow rope over the crest of an indentically sloped hill connecting two identical trucks (again, ignoring friction). The truck going down at some speed would exactly pull the one going up the other side at the same speed. The HP needed to pull the one up equals the HP "created" by the one going down. In this example the truck rolling down is using up the power by pulling the other one up, rather than simply making heat.