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

A bunch of places these days (such as my work) have special parking reserved for hybrids. I have been toying with the idea of putting together some kind of hybrid drive for the 58 just to troll security.

I also just sorted out that I have a 265 rather than the 283 I thought I had.

What weird problems would I create by using the PTO port on the SM420 for an electric assist? I am envisioning something similar to the GMT800 system that used a 48V motor in the bellhousing to provide a torque boost.

I am not worried about the controls side of it, more the mechnical problems I could run into from backfeeding the PTO.

YESSSSS!!!!! Go for it! Anything to tweak the tree huggers' noses is OK in my book! You could even use a small 3 or 4 speed transmission between the drive unit and the PTO to give some extra torque for getting the vehicle moving from a stop- - - - -maybe a passenger car 3 speed from a torque tube driveline from the early 1950's. Those transmissions are tiny, but they had enough torque capacity to move a full size car down the road.

Since the PTO drives through a set of straight cut gears on the cluster gear assembly, there would be some noise involved. At one time, the big 28 volt DC starting motors for radial aircraft engines were dirt cheap from military surplus outlets, but those things were WW II surplus. It took a lot of torque to crank up a 9 cylinder, 1200 HP Wright Cyclone engine on Dad's B-17. The truck pullers used to adapt them to run a hydraulic pump for power steering on their pulling rigs.
Jerry

If this guy [thefoat.com] can do over 100 mph in the 1/4 mile on two forklift motors, you could hook one up thru a PTO on your truck. You'd have plenty of room for batteries in the bed. BTW, that video was taken at the drag strip I used to run on just north of Anchorage. That pass wasn't quite 100 MPH, but I've seen him do over 100.

I was thinking something like this: https://www.evwest.com/catalog/prod...;osCsid=2966c1ba58f8827f28b96223aa30f1f9

48VDC could come from 4x batteries mounted along the frame rail under the bed. It has 70ft-lbs of torque up to about 2000RPM, which is about where the 265 gets its wind.

It would take some creativity to couple the potentiometer throttle with the engine throttle, but nothing some time with the mill couldn't solve. The regenerative braking system comes with a mode for operation inline with the brale lifht switch.

If the PTO would not get mad being backdriven at those speeds, I think it would be fairly easy to do.

Now I just need to find a PTO and a few thousand dollars to build it...

As far as the noise, I suspect it would be similar to the electric humvee I built in grad school. It had a straight cut planetary for the "transmission" as well. It was a lot of fun to bang around in and mess with people.

How do you intend to get 48 volt Alternating Current from DC batteries?
Jerry

I have an extra 420 PTO if necessary!

Ed

The controller takes 30-60 VDC and converts it to AC to run the motor.

Honestly I am just toying with the idea. I was half hoping the design of the PTO would prevent it so I could put the idea to rest.

My top priorities are getting my brakes and rear diff in order so I can safely get on the road. Once it is safe to stop and go, then I can start considering other upgrades.

The current sticking point that I need to think more about is shifting gears. Since the PTO is on the transmission side of the clutch, the electric motor would stay engaged even when the clutch was pressed in. As long as the driver did not try to rev match using the throttle, it should work if the regenerative braking was turned down. Most EVs and controllers* start regenerating when the throttle is below a programmed threshold. That would wreak havok on shifts, but it looks like it can be turned off in this particular controller.

The ROI on this idea would be purely entertainment to screw with the treehuggers and show off at car shows. There is certainly some value to that, but maybe not enough to be worth the cost. The upside is that I could be driving it while working on it by just disengaging the PTO.

The GMT800 version of this picked up 2-3mpg city and lost about 1/2mpg highway, so the operating cost benefits are pretty minimal.

I sat down for a while after my transmission thread and spent a while re-evaluating my short term and long term goals and have backed off a lot of the things I was going to do right away. I originally planned to get it on the road quickly so I could start enjoying it, but I fell into "while I am here" scope creep and it ballooned into a much larger project.

My long term plan is to do a high tech tech upgrade to GMT800 technology across the board (LS, AWD, ABS, etc), but that is a 10k+ project and I just don't currently have the resources for it. Once I get it driving (hopefully this summer) I can decide if a mild hybrid conversion would entertain me enough to push out the big upgrades.

*all that I have worked with, but I am not willing to commit to it being a universal truth

Use an intermediate roller clutch from a Turbo 350 transmission to let the drive free wheel while you're shifting. Just machine an aluminum housing to adapt the roller clutch between the drive motor and the transmission. The vehicle will freewheel as you let off the loud pedal and allow up and down shifts with no load on the driveline.
Jerry

Jerry, I will have to look at how that would work. I am not intimately familiar with the inner workings of the TH350. Is it a one way clutch like a ratchet or something? Or would it need an additional linkage to engage/disengage?

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.

From what limited information I can find, there were (are) many ratios available. If I limit my search to 6-bolt PTOs, the closest to 1:1 I can find in modern documentation is a 2:1. Most appear to be 4:1 or 8:1. I am still having trouble determining compatibility on those though.

The pto ratio depends on specifically which pto is mounted to the transmission
The input shaft is about 20 teeth
The intermediate shaft is about 40 teeth
That gets you to 1/2 engine speed
The intermediate shaft presents about 33 teeth to the pto gear
I studied a photo of one of my pto parts and it looks like it’s about 24-26 teeth
So the pto is doing about 60-70% of engine rpm
This is anecdotal data
But usually the pto is slower than the engine
I would not recommend exceeding about 150 ft/lb of torque or maybe 10-20 HP into the pto input without doing a more thorough study of the forces involved, maybe it could handle more but I don’t know if the original tiny thin pto casting could do it, might pop off, that’s how they fail when you forget to disengage the pto and drive down the road with too much torque on them.

Enclosed is picture of 420 Chelsea PTO, cannot read MN. Some numbers visible on casting. Bronze or brass bushings, 26 teeth. Not sure bushings would stand duty required for an alternator/generator!

Ed

Ed, that is extremely helpful. Thank you.

Looks like that PTO is a 0.86 drive ratio and rated for 225 ft-lbs intermittent use (defined as 5min per 15min interval).

The motor I am looking at is 70ft-lbs of torque up to 2000rpm. With that drive ratio, that would be 60ft-lbs up to 2300rpm. That is comparable to the torque of the hybrid system that GM put in suburbans in the early 2000s and it would push them up to about 20 (supposedly 35, but I have found a lot of evidence that it was not that strong). This truck weighs about 1/3 of a modern suburban with the aero of a brick, so I would expect at least similar performance.

I agree that the bushings look like the weakest point. It would probably be prudent long term to replace them with real bearings. That starts down a long and potentially endless path of strength upgrades.

Since you would need to do some metal machining work
Maybe attaching your motor directly to the drive shaft at the output of the transmission with a 2:1 ratio chain drive would be more ideal
Saves the pto for pto things
And fixes the rotation intermediate gears issues and clutch and
Pilot bushing possible wear issues.
Find a transmission with the brake drum and swap that for a big chain gear.
2:1 on the drive shaft multiplied by the rear end ratio gets you at the typical motor to wheel ratios of all the modern electric vehicles on the road today, 5.x-8.x typical.
-s

To replace the bronze bearings with roller or ball bearings would require a whole new housing. The bearing retainer area is very thin, strong and thick enough for existing use, not for larger bearings.

Ed

Another thought would be to attach a 4wd transfer case on the back of your 420(Novak makes an adapter), so something could be driven off the extra(front) output that could be controlled separately from the truck driveshaft.

Ed

My original idea was to put a solid axle up front with an electric drive on it and keep the engine/trans/rear axle stock.

The thickness of the PTO housing is deeply concerning. That is probably the biggest reason this is a bad idea.

Don't do it.
Nobody else will say it.
I don't really mean it.
Just giving you an out if you wanted to take it.
(Anyone on this site who knows me personally will tell you that, above all else, I am best known as a giver.)

So i have been thinking about all the suggestions on this..................

If one were able to do the following I think it would be a win:

1. Electric motor will be attached to the DS at the tail of the transmission. Whether the DS goes through the motor or it has some type of gear chain attachment i don't think matters.
2. Have a connection like a MC starter does. Don't know the techy name for it, but it grabs one way to crank engine, then when engine moves faster it releases. If you want regen braking do away with this idea.
3. Electric motor will be activated with a POT on the gas pedal. That way when you shift it pauses as well.
4. Pick the amount of HP and battery life you want.
5. Find a guy smarter than I am to figure out the details of this, but I do think it would work.

More power to you but I think between the gear reduction and the weight and drag of the truck you are way beyond the design of the PTO for anything more than going across the yard. Go for it. It never stops me. Nobody told the bumblebee it couldn't fly.

It was an interesting idea for discussion/planning, but between the limited bushings on the PTO and emergent financial limitations I think this idea is pretty much dead.

The idea is interesting, but I believe the only viable option would be to weld up a housing of heavy steel plate with tapered roller bearings that will bolt to the PTO opening, and use the gears and other components from the original PTO. That would be quite an exercise in precision machining to make it work. If I manage to win the nest multi-million dollar Powerball lottery I might just tool up and do something like that.
Jerry

I found this thread late, but I think the idea is quite interesting.

The biggest issue I see would be that the tree huggers, once you got your "hybrid" up and running, would issue a company definition of acceptable "hybrids", and yours would not qualify. Definitely sore losers!

Jon

In this case, they can't because the definition is set by an international certifying authority (LEED). I dis explicitly look into that first.

Weld up a tapered roller bearing housing that will bolt to the PTO opening that will put a planetary gear set between the drive motor and the cluster gear. That will slow down the input speed to the cluster to prevent overspeeding it.
Jerry

Fibonachu This is way late and probably not thought out very well,mount a sheave (pully) on your driveshaft,belt up your golf cart motor. Put your sheave ahead of the carrier bearing in the crack between the cab and bed (if needed). Get it so you can take the belt off for hi-way work or just park it up in there. Use the golf cart controls so your brakes will work. Could use one of those belts you can separate. I guess with an electric clutch you could just let the belt run full time. Just a thought, been working on our golf cart used in our big yard,lot of stuff there. With this system just put the driveline in neutral could let the engine idle for heat,steering etc.or turn it off.