Stovebolt.com Forums The Shop Area The HiPo Shop Someone talk me out of a crazy idea...

I am thinking a one way bearing line on MC starters would be ideal for the attachment to the PTO. Once it gets to speed it releases automatically. You will need to figure out a shut off for the motor.

The PTO has to have a massive gear reduction, doesn't it? How will you deal with shifting while it wants to put power into the system?

You'll need to figure out a way to disengage the main engine clutch, and keep it disengaged, such as locking the pedal down to the floor while running on electric power, since the cluster gear is meshed with the input shaft and will turn it, and the clutch disc anytime the cluster is in motion. A PTO engages a straight cut spur gear on the cluster (counter) gear. How do you intend to avoid wearing out the throwout bearing?
Jerry

Making it possible to run on gas *or* electric is easy. Run on gas with the engine on and the PTO disengaged. Run on electric with the PTO engaged and the clutch locked in.

The throwout bearing should be fine because if the engine is not running, the clutch and bearing will not be spinning, right?

I am having some touble finding the gearing on the PTO to do the math and see what gear(s) the electric motor could direct drive it at what speeds. All I can find is "they vary wildly so make sure the one you get meets your needs".

The more interesting problem would be using it in hybrid mode with both gas and electric enabled. That is where the controls become more interesting and the issue of depowering the electric side for shifting becomes relevant. The max RPM of the electric motor (7k) is higher than redline on the engine (4.5k), so having them coupled via the clutch/input shaft would not be inherantly problematic (depending on PTO gearing).

Or you could just go with GM's crate EV package (when it becomes available.) Probably an easier conversion, but mega-dollars instead of mega-hours.

That is assuming it ever actually exists. I will F*** credit that their EV conversion system is available for sale.

Besides, what is the fun in buying an off-the-shelf unit that any monkey with a toolbelt can install? It is the home-built crazy stuff that is really fun. I mean, why do you think we keep Jerry around?

Good catch on the flywheel and pressure plate not turning. An either/or situation could be addressed much more easily than a scenario where both systems were running at the same time. As long as the countergear is turning, all of the reduction gears should transmit power, and high gear will be available by the countergear driving the main input shaft. That will be a massive overdrive situation, since the input shaft will be driven at least twice as fast as the countergear. You'll need a LOT of gear reduction between the electric motor and the PTO, and unless the motor is reversible in some way, you might end up able to go VERY fast in reverse, with several speeds available, and only one forward speed. How are your mirror driving skills?
Jerry

The direction of rotation is easy. It is an AC induction motor, so swapping 2 of the phases will reverse the rotation.

Looking at the programming guide, it has a clutch de-power mode explicitly for use with manual transmissions.

This might not even be that hard to set up.

Durn you Jerry, you were supposed to make me abandon this plan, not figure out that it wouldn't be that bad.

I wonder what the closest to 1:1 gearing I could get in a PTO would be. Any ideas where I could find that info? My search-fu is failing me.

Edit: Chelsea has a pto/pump chat that gives pump to engine speed ratios in the 99%-103% range with torque ratings in the 360+ ft-lb range. That would be more than enough torque and a good RPM match. Those are for allison transmissions though, not having much luck finding a muncie equivalent table.

Good point. Count on Jerry for being the cobble-king.

The more interesting problem would be using it in hybrid mode with both gas and electric enabled. That is where the controls become more interesting and the issue of depowering the electric side for shifting becomes relevant. The max RPM of the electric motor (7k) is higher than redline on the engine (4.5k), so having them coupled via the clutch/input shaft would not be inherantly problematic (depending on PTO gearing).[/quote]

The PTO is not a 1 to 1 I don't think? If it is, it will make your life easier, but I believe there is a significant reduction?

Could a guy that has a PTO SM420 just do some shaft turning and rotation counting?

I don’t recall from memory how much the shop manual has to say about the PTO. There might be a grainy pic of the gears themselves that one could do some math.