[Shepherd777]

Originally Posted by JRMichler

That series hybrid will need one huge electric motor. Just to throw out some numbers:

Assume tires 40" diameter.
Assume 80,000 lbs gross vehicle weight.
Assume it needs to pull up a 10% grade at low speed.
Assume geared for 1260 RPM at 55 MPH, that would be a 2.5:1 rear axle ratio.

You would need 8000 lbs traction force plus another 1000 lbs for friction and whatnot.
That's 9000 X 20 / 12 = 15,000 foot-lbs torque at the drive wheels.
15,000 / 2.5 = 6,000 ft-lbs at the drive motor.

If the main engine is 450 hp, that would feed a 400 hp electric motor.
The electric motor would be rated for 6,000 ft-lbs up to 350 RPM (400 hp).
Above that, it would run in constant power mode.

I'm not aware of any off the shelf electric motors anywhere close to those specs. Which would explain why the big manufacturers did not develop series hybrids for Class 8 trucks. In order to get the motor frame size down to where it will fit in the truck, I think it will need liquid cooling.

Your first two assumptions are correct.

Max grade on the interstate highway system in the U.S. is limited to 6%. A short 10% grade on a back road in Somewhere, USA should not be a problem.

Your 2.5:1 axle ratio assumption is incorrect. But I cannot elaborate in public.

I really cannot get into the math on the internet. I appreciate your calculations. All of our math is just physics and absolutely quantifiable.

Remember, in both Parallel and Dual Mode hybrid, the vehicle is powered exclusively by the electric motor only, during certain operation cycles.

A big manufacturer does indeed make off the shelf traction motors and motor/generators for our application. That application being a series hybrid Class 8 truck. The big manufacturer is Indiana based Remy. So the motors are not built in China, but in the good-ol' USA.

Large OEM's do currently make Series hybrid drive large-capacity buses, and large trucks such as garbage trucks. No OEM currently makes OTR Series hybrid drive trucks.

They are indeed liquid cooled and Dexron VI ATF is used as the coolant.

Remy's sister division, Delco Remy, has been a Partner of ours for four years now.

The torque and power curves shown below are not necessarily correct for our application, and are posted for your reference and perusal only.





Again, I appreciate your credentials and thoughtful calculations, but I really cannot elaborate any further on the internet.