# Electric motor to drive hydraulic pump



## jrscsllc (Dec 5, 2021)

Hello all, 

I'm new here. After an extensive search for a electric driven hydraulic system found this site. I have very little knowledge of EV's but by the looks of things believe a solution may be found here using ev conversion parts and ideas. 

I have a mid sized truck with a very limited hydraulic source and need to run several hyd functions.

1- a valve block to run 6 different boom cylinders independently.(8-10 gpm requirement)
2. 2- hyd driven water pumps (requiring a combined 22 gpm at 2800 psi)

Here is what I visualize-

A electric motor direct driving a 32 gpm pressure compensated pump.

A Tesla style battery to run the motor.

A PTO mounted generator to keep the battery charged. (The reason I can't use the PTO to run a hydraulic pump is because I need it to run while driving and when the truck comes to a stop. The problem is when the truck comes to a stop the pto stops unless the trans is in neutral or park) 

If anyone has recommendations or a better solution, I'd be glad to hear.


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## brian_ (Feb 7, 2017)

22 GPM at 2800 PSI is a hydraulic power of 36 horsepower or 27 kW; of course the pump is not perfectly efficient so the electric motor would need to produce more than that at peak. The generator power output required would depend on the duty cycle of the hydraulic operation and the available PTO running time.

It looks feasible to me. 

While Tesla modules would work, there's no need to use them specifically. Perhaps you just meant lithium-ion battery modules, salvaged from a wrecked EV... and that makes sense.


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## remy_martian (Feb 4, 2019)

^^ The PTO should not stop if it is driven from the input shaft of the transmission and the engine is running.

I don't think I've ever seen a ground drive PTO on a truck. Farm tractor, yes.


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## brian_ (Feb 7, 2017)

remy_martian said:


> ^^ The PTO should not stop if it is driven from the input shaft of the transmission and the engine is running.
> 
> I don't think I've ever seen a ground drive PTO on a truck. Farm tractor, yes.


There are many PTO styles, and if I recall correctly what jrscsllc describes is the behaviour of some of the PTO in some lighter-duty designs; it even came up in a previous discussion in this forum, although I haven't found that one yet.


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## jrscsllc (Dec 5, 2021)

brian_ said:


> 22 GPM at 2800 PSI is a hydraulic power of 36 horsepower or 27 kW; of course the pump is not perfectly efficient so the electric motor would need to produce more than that at peak. The generator power output required would depend on the duty cycle of the hydraulic operation and the available PTO running time.
> 
> It looks feasible to me.
> 
> While Tesla modules would work, there's no need to use them specifically. Perhaps you just meant lithium-ion battery modules, salvaged from a wrecked EV... and that makes sense.


Glad to hear is is feasible!


brian_ said:


> There are many PTO styles, and what jrscsllc describes is the behaviour of some of the PTO in some lighter-duty designs; it even came up in a previous discussion in this forum, although I haven't found that one yet.


That's correct. This is a International CV515 with a 2000 series Allison. The PTO mounts on the transmission, but runs off the engine side, where as the 3000 series Allison runs off the trans side.


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## remy_martian (Feb 4, 2019)

He needs to use an engine driven PTO which can be installed on any mid sized truck transmission.

Using electric motors and Tesla batteries is insane unless it needs to work with the engine off, which was not in the constraint statement.


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## brian_ (Feb 7, 2017)

remy_martian said:


> Using electric motors and Tesla batteries is insane unless it needs to work with the engine off, which was not in the constraint statement.


I wouldn't say "insane", but certainly an installation in which the engine doesn't run continuously is the ideal application for this sort of electric drive system.


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## jrscsllc (Dec 5, 2021)

brian_ said:


> 22 GPM at 2800 PSI is a hydraulic power of 36 horsepower or 27 kW; of course the pump is not perfectly efficient so the electric motor would need to produce more than that at peak. The generator power output required would depend on the duty cycle of the hydraulic operation and the available PTO running time.
> 
> It looks feasible to me.
> 
> While Tesla modules would work, there's no need to use them specifically. Perhaps you just meant lithium-ion battery modules, salvaged from a wrecked EV... and that makes sense.


I'm glad to hear it is feasible! Where 


remy_martian said:


> He needs to use an engine driven PTO which can be installed on any mid sized truck transmission.
> 
> Using electric motors and Tesla batteries is insane unless it needs to work with the engine off, which was not in the constraint statement.


The issue is with the transmisson, not the type of PTO available. The way I understand it is that the gears inside the PTO access only run while the truck is moving forward, in nuetral or in park.


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## remy_martian (Feb 4, 2019)

No. The PTO is torque converter turbine driven. Whenever the engine is running, it runs. 










There may be an electrical lockout, which is unlikely, but defeating that is one heckuva lot cheaper than dropping 5 grand on an electric setup


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## brian_ (Feb 7, 2017)

remy_martian said:


> He needs to use an engine driven PTO which can be installed on any mid sized truck transmission.


"any mid sized truck transmission" apparently means not the that jrscsllc has, which is apparently a "less-than-mid-sized truck transmission"... whatever that means. 

The industry terms for trucks are light-duty, medium-duty, and heavy-duty. "Mid-sized" presumably meant medium-duty. Allison seems to have a break in their product line with 3000 series and up having different features, including the type of PTO which remy-martian is expecting; there are certainly 2000 series transmissions in medium-duty trucks, but they're not likely a suitable choice where PTO operation is important.

Changing transmissions to one which is not normally available in that truck would not likely be trivial, but it would still be easier than adding an electric drive system.

Just curious, jrscsllc... what's the truck?


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## remy_martian (Feb 4, 2019)

I said PTO, not transmission, installed. Almost all medium trucks have a PTO provision on the tranny.


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## brian_ (Feb 7, 2017)

remy_martian said:


> No. The PTO is torque converter turbine driven. Whenever the engine is running, it runs.
> 
> View attachment 125376
> 
> ...


Excellent research. 

Now read it again, and you should see that this reference confirms what jrscsllc said: the PTO appears to be driven by the *output* side of the converter (the turbine, *not *the impeller), so it turns "whenever the vehicle is moving or whenever the vehicle is stopped with the engine running and the transmission in Park or Neutral" (to quote the reference source), not "Whenever the engine is running". Stop moving in Drive (or anything other than neutral, Park is just neutral with a parking pawl engaged) and the PTO stops. When not in neutral the turbine, and thus the drive to the PTO, turns at the road speed multiplied by the selected gear ratio, not at the engine speed.

Specification sheets for the 2100/2200 Series and for the 1000 Series list the PTO drive as "Torque converter turbine-driven spur gear", while the specification sheets for the 3000/3200 Series, for the 4430/4440/4500/4600 Series and for the 4000/4200 Series list "Engine-driven helical gear". Those points are separated by the torque converter, and that's the critical difference.


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## jrscsllc (Dec 5, 2021)

brian_ said:


> 22 GPM at 2800 PSI is a hydraulic power of 36 horsepower or 27 kW; of course the pump is not perfectly efficient so the electric motor would need to produce more than that at peak. The generator power output required would depend on the duty cycle of the hydraulic operation and the available PTO running time.
> 
> It looks feasible to me.
> 
> While Tesla modules would work, there's no need to use them specifically. Perhaps you just meant lithium-ion battery modules, salvaged from a wrecked EV... and that makes sense.


Yes, I just meant that style battery I guess in this case it would be a "buffer" battery since I would be charging it while in use. I could get up to 17 gpm from a deweze serpentine driven pump which would be plenty for the cylinder functions I spoke about and then isolate the remaining requirments for the centrifugal pump to this electric solution. At that point could possibly run the pump directly from the AC motor and not even use hydraulics? Currently the speed of that pump runs off a hyd PWM valve with a 0-12 volt PWM input to regulate speed. The speed control must be very fast and precise. Are there any speed controllers that could accept a 0-12 v input to regulate the speed of the motor?

The centifugal pump max hyd psi rating is 4000 psi at 14 gpm, so that would be approx a 32 hp requirement. That would be very rare to max it out like that, probably 75% of the time it would be a third to half of that at approx 10 hp continuous.


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## brian_ (Feb 7, 2017)

remy_martian said:


> I said PTO, not transmission, installed. Almost all medium trucks have a PTO provision on the tranny.


I was referring to the "any mid sized truck transmission" comment. Clearly, there are differences in transmissions which determine what can be done with a PTO; the transmission design determines how the PTO can work.


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