[windrider919]

Hi all. Well, I'm new here but I will throw my two cents in.

Why do so many state that the motor would be overspeeding when the engine is driving it? Motors usually are variable speed or constant speed but in my experience as a millwright run at 1800, 3600 or 4800RPM. I have even seen specialty motors run at 6k RPM. Now most piston engines have an RPM range of 600(idle) to 4500 [+- redline, depending on part balance, etc] and then the torque is delivered to the transmission which.....wait for it......REDUCES the output RPM.

In lower transmission gears, the engine creates more RPM and more horsepower, which is important for accelerating when taking off. In straight drive, the output of the automatic transmission is turning at the exact same speed as the engine. In a manual transmission the same rule applies in the gear before overdrive. In overdrive, the output of the transmission is actually turning at a faster speed than the engine. Overdrive is great for fuel mileage. But even then we are only talking maybe 10% faster. Changing the trucks gear axle ratio, affects the engine RPM at a given speed and the wheel speed. As an example if the objective were to save fuel, the axle ratio would be changed to a higher gear ratio. If the trucks gear ratio is 4.10 and was changed to a higher ratio like 3.55, the engine would turn approximately 15% slower, everything else being equal.

Since most engine / transmissions gearing are set to cruse at 2400 to 3600RPM at 55/60 down the road the drive shaft must be turning at a RPM either slower or at about engine RPM.

Roughly calculating backwards (reverse engineering as a check):
24” tall tire x 3.1415 = 75.4” / 12 = 6.283' circumference

1Mile = 5280feet

60mph = 5280 ft/min / 6.283' = 840.36 RPM of the tire

With a 3.5:1 rear end that should be: 3.55 X 840.36 = 2983.3 drive shaft RPM

So an electric motor would NOT be overspeeding in direct drive.

Note: In this application, Brake regeneration would work quite well to recharge the battery bank For example, in Ford F350s there already is a drive line brake which is also the emergency brake. It might require some control synchronization but the hardware is already out there.

In this application the electric motor would be able to INCREASE the torque to the rear end if used in combination with the IC engine if linked to the engine throttle. With todays high torque motors the acceleration could be awesome with low 0-60 times.

Another point that I saw was that the engine powers the power steering and the brake booster. If the engine is cut off the control forces will increase significantly. Unless they have been disconnected from the engine and powered separately. Again, that conversion is available as a kit for increasing available engine HP just like electric fans replacing direct drive fans do.

If a manual transmission then switch over would be easy, put it in neutral and kill the engine, drive on electric. But if the truck is an automatic then there is the problem of the trans fluid pump not operating when the engine is not running. It would be the same as if the truck were being towed. And everyone should be aware that the trans bearings will burn up from lack of lubrication in a short (relatively) period. hats why tow trucks lift the drive wheels on an automatic transmission vehicle. Again, there are kits to correct this situation. Cars with auto trans being towed behind RVs MUST have an auxiliary electric pump to circulate the trans fluid while being towed. That too could be added to the truck. Another point was made of adding the motor torque into the transmission via the transfer case. That could work but I question how some of the clutches, etc would work if driven backwards. And of course there is the battery bank to be considered, expensive no matter what type used because you need so many of them for any mileage at all.

The bottom line is that it is probably not a economic conversion. It could be done but the hybrid vehicle would be the worst of all worlds. At least in my opinion. Thats why we don't see them on the streets today, not cost effective.

Hey, I'm new. Like I said, my .02 worth.