# Gearing Up?



## Jimdear2 (Oct 12, 2008)

I've seen those boxes, they are farm equipment which means they are a bit rough around the edges with lots of backlash on straight cut gears (noisy). That's on the ones I've seen . . . the ones you are looking at may be better. I also would be a bit concerned about running at twice design speed because of heat buildup, maybe an upgrade to the bearings and lubricant. Also check to make sure the gears have been heat treated.

Seems to me using a box like this would sure open up your choice of motors allowing use of more splined shaft motors without a lot of machine work.

One of the big problems that I have seen is how to reconcile electric DC series motors which run best at lower RPM with vehicles that were designed around higher RPM ICE engines.

Looks like a good find, why don't you post a link.




green caveman said:


> Before I spend too much (more) time researching this, I'd appreciate comments from more knowledgeable/experienced minds.
> 
> The output shaft of the 36V forklift motor I have matches the spline pattern of some of the tractor PTO's out there. This set me thinking that if I add, say, a PTO generator gearbox, I can increase the engine speed and run the motor at a lower speed. I could, presumably, also run the motor at a lower voltage (with the problem of lower power or more amps) and still maintain a decent road speed.
> 
> ...


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## green caveman (Oct 2, 2009)

Jimdear2 said:


> I've seen those boxes, they are farm equipment which means they are a bit rough around the edges with lots of backlash on straight cut gears (noisy). That's on the ones I've seen . . . the ones you are looking at may be better.


Ah! Good point. I was thinking that any PTO gearbox with a decent ratio would work, but, as you point out, the gearbox from a manure spreader may not be ideal.



Jimdear2 said:


> I also would be a bit concerned about running at twice design speed because of heat buildup, maybe an upgrade to the bearings and lubricant. Also check to make sure the gears have been heat treated.


You could probably cruise around town with the motor running close to 540RPM, or less. Prolonged highway driving may be a problem. I should calculate the ratios for the Sidekick. I'm just judging from the metro which is 4000rpm @70mph. At 50mph you'd be ~60% overspeed, the Sidekick is probably a little better. Practically, where we live, 50mph is a reasonably upper limit - there are no freeways within the range of the vehicle.



Jimdear2 said:


> Seems to me using a box like this would sure open up your choice of motors allowing use of more splined shaft motors without a lot of machine work.


I agree. I have the motor and I was just happy that someone else figured out the PTO match which should make the coupler easier. I would never have figured out the match - it took me about two weeks to figure out that PTO stood for "Power Take Off" and that it was a standard tractor component. (Thanks to all forum member for any help I've received).

Not having to machine splines is, clearly, a major cost saving even if you have to cut/modify the disc.



Jimdear2 said:


> One of the big problems that I have seen is how to reconcile electric DC series motors which run best at lower RPM with vehicles that were designed around higher RPM ICE engines.


Is "best" in this case just torque, or are there other advantages?



Jimdear2 said:


> Looks like a good find, why don't you post a link.


I hate to post ebay links because the auctions go away, but this is one that get me started thinking of this:

Generator PTO Gear Box

but that doesn't (directly) fit the motor. 

Something more like this which has a female input would be better if the motor fit directly because it would be easier to mount (and all the other obvious reasons).


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## Woodsmith (Jun 5, 2008)

OT



green caveman said:


> I hate to post ebay links because the auctions go away, but this is one that get me started thinking of this:
> 
> Generator PTO Gear Box
> 
> ...


If these gear boxes are smooth running could they be run as reduction gear boxes?
They sound ideal as a reduction box for those who want to run a direct drive. Fit one of these between the motor and the high ratio diff normally found on modern cars to get a good direct drive ratio.

The female shaft on the small gear would be idea for motor coupling if the splines match. The one with the male shaft could be splined to match the female shaft of some big pump motors.

Just a thought.


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## green caveman (Oct 2, 2009)

Woodsmith said:


> If these gear boxes are smooth running could they be run as reduction gear boxes?


I would need it to run both ways since I want regen braking. 

How about this from Surplus Center.

What's a MID-MOUNT PTO GEARBOX?

There is also a selection of right-angle gear boxes around the net, but I'm not sure I could fit the motor sideways. Could stick it out through the hood/bonnet like a turbo charger.


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## EV-propulsion.com (Jun 1, 2009)

A midmount PTO is typically mounted on the front side of a transmission, on the engine driven side of the transmission. This means that the transmission can be in neutral and still operate the accessory. A rear PTO is driven by the output of the transmission, so the transmission would have to be in gear for the accessory to operate.

Very interesting idea I might add. Some Pto's handle alot of load. Costs may be prohibitive though.

Mike
www.EV-propulsion.com


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## Jimdear2 (Oct 12, 2008)

green caveman said:


> I would need it to run both ways since I want regen braking.
> 
> How about this from Surplus Center.
> 
> ...


The item (this) from surplus Center only weighs 8 lbs., it might be ok for use as a gear reducer on a very light vehicle but not a 2000 - 3000 lb car. Same with the other one shown with the female spline.

The mid mount PTO is used to drive things like belly mount mower decks on small tractors. The big drive gear engages into a gear on the input of the transmission through a hole in the housing, you remove a plate for access. The external lever shifts it in and out of gear. Again it's pretty light duty and not something usable on a car.

To answer Woodsmith's question. These things are farm equipment, cheaply made but will generally will take a lot of abuse. The tolerances are not close and they generally use straight cut gears, very noisy. If you wanted to use one as a gear reducer, the generator drive unit shown in an earlier post would probably work when run in reverse, I think that one is prety hefty.

Another one to look at are the units that use a hydraulic motor to drive a shaft that is in a housing that can be mounted to mimic a tractors PTO Shaft.

Happy Hunting.


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## green caveman (Oct 2, 2009)

EV-propulsion.com said:


> A midmount PTO is typically mounted on the front side of a transmission, on the engine driven side of the transmission. This means that the transmission can be in neutral and still operate the accessory. A rear PTO is driven by the output of the transmission, so the transmission would have to be in gear for the accessory to operate.
> 
> Very interesting idea I might add. Some Pto's handle alot of load. Costs may be prohibitive though.
> 
> ...


Mid-mount is $50 at Surplus Center. I wish that they had a picture of the other side of the device so that I could understand it better. It sounds as though there should be a shaft there also, but perhaps the transmission just meshes with the exposed gear. It looks as though it might be noisy/rough.

The boxes are in the few hundred dollar range. The adapter plate cost would basically double though since you almost need two. 

Of course, if it doesn't work then it becomes expensive because you're out the cost of the box and another adapter plate to direct connect the motor.


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## Woodsmith (Jun 5, 2008)

Jimdear2 said:


> To answer Woodsmith's question. These things are farm equipment, cheaply made but will generally will take a lot of abuse. The tolerances are not close and they generally use straight cut gears, very noisy.


A case where calling it 'agricultural' wouldn't be derrogatory I guess.


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## EV-propulsion.com (Jun 1, 2009)

Oh yes, that midmount is definitely not usable, as jimdear has stated. For a strong enough gearbox, if available, would be well over 2 thousand dollars in my opinion. Something like this shown earlier might be more usable-I'm sure its not cheap if it is large enough











​


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## green caveman (Oct 2, 2009)

Jimdear2 said:


> Another one to look at are the units that use a hydraulic motor to drive a shaft that is in a housing that can be mounted to mimic a tractors PTO Shaft.
> 
> Happy Hunting.


Good lead,

Hydraulic Speed Increaser/Decreasers
(There must be other manufacturers)

As the old joke goes, now we're just arguing about the price.


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## green caveman (Oct 2, 2009)

EV-propulsion.com said:


> For a strong enough gearbox, if available, would be well over 2 thousand dollars in my opinion.


This is $300 on eBay (one of the original links) and claims
to be good for up to a 40kW generator.








I'm just quoting the page and no other information as to whether it would be suitable for running a car. The $2K may be a more realistic figure for something that would work well, quietly and be durable/reliable.

It does seem you can use it to increase or decrease the speed. From the seller:

"Yes, it works in any direction, CW or CCW and you can reverse the input. YOu can turn the high speed end and it will reduce the output speed
Thanks, hope this helps."


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## martymcfly (Sep 10, 2008)

A couple of silly questions. I am wanting to convert a motorcycle, but the donors that I have found have all been shaft drive. The shaft is one to one at the back wheel. Do these come in any different ratio's? Could I use one of these to get a desireable ratio for a 72 volt motorcycle?


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## green caveman (Oct 2, 2009)

This is a John Deere box, about $750. Would anyone venture an opinion on whether it will run in both directions? Any general comments?

From my understanding, if I add some sort of gearbox I will be able to run the motor a lower speeds which will give me more torque/power and also allow me to run the motor at a lower voltage. Do I gain any other efficiencies, more range, lower max amps, etc. etc.? I would expect that the range might even decrease since I'm adding more moving parts. Would anyone care to correct/speculate. Thanks.


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## Jimdear2 (Oct 12, 2008)

green caveman said:


> This is a John Deere box, about $750. Would anyone venture an opinion on whether it will run in both directions? Any general comments?
> 
> From my understanding, if I add some sort of gearbox I will be able to run the motor a lower speeds which will give me more torque/power and also allow me to run the motor at a lower voltage. Do I gain any other efficiencies, more range, lower max amps, etc. etc.? I would expect that the range might even decrease since I'm adding more moving parts. Would anyone care to correct/speculate. Thanks.


It will run in both directions and with the angle cut gears probably be quiet. Without knowing it's original function, its size and torque rating, I cannot guess if it will do what you want.

Nice looking box.


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## green caveman (Oct 2, 2009)

Jimdear2 said:


> It will run in both directions and with the angle cut gears probably be quiet. Without knowing it's original function, its size and torque rating, I cannot guess if it will do what you want.
> 
> Nice looking box.


It's sold as a PTO generator gearbox. I 'm trying to find the ratings, HP and speed. In desperation I may have to go through and find the biggest generator for which they sell it as an accessory. If it would work on a 1000 RPM PTO and has enough torque it would seem to be a workable solution.

BUT, is it really worth it, or am I just adding complexity to the conversion without really adding much value?


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## Woodsmith (Jun 5, 2008)

Running it as a step up or step down won't affect it but running it backwards from its original direction of rotation might.

Helical cut gears have an axial thrust.
If a motor was attached to the small gear and turned CW it will thrust towards the motor. If it is turned CCW it will thrust away from the motor.
Likewise the larger gear will also thrust one way or the other regardless of whether it is the driver or the driven gear.

The box will need to be able to bear the end thrust either through the ball bearings or on thrust bearings on the shaft ends or on the face of the gears.

So depending on how it is constructed reverse direction of drive may or may not be a problem.


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## green caveman (Oct 2, 2009)

Woodsmith said:


> Running it as a step up or step down won't affect it but running it backwards from its original direction of rotation might.
> 
> Helical cut gears have an axial thrust.
> If a motor was attached to the small gear and turned CW it will thrust towards the motor. If it is turned CCW it will thrust away from the motor.
> ...


Do I understand you correctly that you are saying the motor attached to the small gear should be turned clockwise, meaning the output will be CCW? In this case, I would need to know the original direction of the engine. You'd think that would be easy, but I certainly don't know.

You're right that the direction is the same at all times, it's just that for regen you're driving the motor rather than vice-versa.
_
Unless there's something odd about the Tracker/Sidekick, then the engine should run clockwise. If this really can't be run CCW, then it won't work._


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## Woodsmith (Jun 5, 2008)

It was really a little bit of an arbitrary post.

All you will need to think about is that there is an axial thrust and the gear box will need to be able to work with that. Quite possibly there is no difference in the gearbox which ever way the thrust is but it is worth checking if a large load is placed on it.

Looking at the gear teeth they are helical, like a screw thread. As the gear is turned it will try to thrust one way or the other, like a screw being turned. Turn a screw one way and it will pull inwards, turn it the other way it will push outwards.
Knowing this you can work out which way the axial thrust from the gear wheels will be.

Now, for those thinking of it as a reduction box in the transmission, if the motor drives the wheels through the box then it will produce axial thrust in the gears in one direction. If the wheels drive the gear box for regen then the axial thrust will switch and go the other direction.
Automotive transmissions are designed to take axial thrust in both directions whereas a PTO box may not as it would not normally find itself being driven by the load.

If you are using the PTO box to only drive a generator then you will need to make sure that it is able to take the thrust in the direction that it will need to be driven in. Reverse axial thrust wouldn't be an issue then.


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## Jimdear2 (Oct 12, 2008)

Green caveman,

As I understand what you want is to use this box to speed up a slow turning hi torque motor's rpm in a direct drive system to give a approx 3 to 1 speed increase. in that case you would be driving the large gear with your motor connected to the splined coupler shaft. 

Automotive drive trains turn clockwise when standing in front and facing the rear of the vehicle. Now I'm going from memory here but I believe a tractor PTO shaft turns counterclockwise (standing in front, facing rear) so this gearbox is designed to take counterclockwise input and output clockwise. Good to go for driveshaft to rear axle rotation.

NOW,

Will the box take a couple of hundred ft. lbs of torque on a high amprage start up from a good sized electric motor in a 2500 lb. car? You would have to ask the manufacturer/designer what the maximum torque is for the box to get that answer. My gut is . . . not for long. Then, there are other problems, what happens when you hit an ice patch, things spin up and then you hit dry pavement. I think the shock load would kill the box.

What happens when the motor is driven by the drivetrain, unless you have a regen system, I don't think there would be a problem. Since the motor freewheels with no current applied I dont think enough force is generated to cause a problem

As far as a axial load from the diagonal cut gears form what I can see and in my opinion, it looks like the box was designed to handle that from either direction.

Woody, 

You may know better then me (probably) but I don't think that diagonaly cut gears generate any where near as much axial load as a spiral (healical) cut gear. The output shaft appears to use the same bearing on both ends so it's ability to take axial loads thould be the same in both directions. The input shaft may have a bigger bearing, but that may be because it had to absorb the side loads from a tumbler shaft type drive shaft.

This box might work in something really small, but a rear 4 passenger conversion, probably not.


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## green caveman (Oct 2, 2009)

I think that the problem with these boxes is that they are horribly inefficient. I've seen numbers in the 70% range, which I assume would translate directly to 30% reduction in range.

Planetary boxes, such as say these seem to do better, 90-95%, but for the torque required seem to be in the $1000+ range.

So, back to the original question, what do I gain? I'm not building a high performance car so more torque at high road speed is not important to me (although I think that these boxes would be good for this albeit at a little added cost and loss of range). I don't think it will make much difference for round-town.

I'm not sure that I have any chance to gain back the 5-10% loss of efficiency by improving the operating range of the motor. That seems to make only a 2-3% difference.

The only real advantage would seem to be running a sepex without interpoles at a lower speed/neutral brush timing to avoid possible regen problems.

I think that Woody's may have the best idea - dump the existing transmission and drive through one of these. (I don't think that I'm going to go there).

Any other thoughts/comments? 

PS Apart from an interesting diversion into the land of gear boxes, I did rediscover the Wheel e-Tractions wheel motor. Interesting way to avoid all the gearbox inefficiencies.


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