Create a PTO by "reverse-application" of a PTO-driven hydraulic pump?

[oldgrayfellow]

The goal:
Make a low-horsepower PTO for installation on a vehicle (mini-truck) that does not have one. (But DOES have a hydraulic pump).

The idea:
Take a PTO-driven hydraulic pump (originally used to power a sickle-bar mower) and connect it to the existing hydraulic pump on the mini truck, so that instead of a PTO driving the hydraulic pump (as in the original design), the hydraulic pump now drives the PTO.

(Put another way, in the original design, a PTO was the power input and the hydraulic pressure was the output.
What i want to do is make hydraulic pressure (from a separate, engine-driven pump) the power input, and make a PTO shaft be the output.)

Would most PTO-driven hydraulic pumps be able to transfer power in the reverse direction this way?

 

[Short Game]

I think hydraulic motors are what would be used in such a case.

http://en.wikipedia.org/wiki/Hydraulic_motor

Conceptually, a hydraulic motor should be interchangeable with a hydraulic pump because it performs the opposite function - much as the conceptual DC electric motor is interchangeable with a DC electrical generator. However, most hydraulic pumps cannot be used as hydraulic motors because they cannot be backdriven. Also, a hydraulic motor is usually designed for the working pressure at both sides of the motor.

 

[oldgrayfellow]

I think hydraulic motors are what would be used in such a case.

Hydraulic motor - Wikipedia, the free encyclopedia

The sickle bar mower has a hydraulic motor that runs the actual sickle. But i was planning to drive that motor from the tractor's own hydraulic pump, and so don't need the mower's original hydraulic pump.

Thought i might be able to make use of the mower's pump to make a PTO as i described, but guess it probably won't work that way (i was afraid of that).

Thanks-

 

[schmism]

The sickle bar mower has a hydraulic motor that runs the actual sickle. But i was planning to drive that motor from the tractor's own hydraulic pump, and so don't need the mower's original hydraulic pump.
Thanks-

so the goal is a device that you can power PTO driven implements off of? Cause if your just talking about this hydraulic sickle bar mower, then just drive the bar head directly off the truck hydrulics with no need to go

truck pump---> hydrualic motor (acting as pto) --> pto pump ---> sickle bar hydraulic motor. just cut out the middle part.

 

[oldgrayfellow]

so the goal is a device that you can power PTO driven implements off of? Cause if your just talking about this hydraulic sickle bar mower, then just drive the bar head directly off the truck hydrulics with no need to go

truck pump---> hydrualic motor (acting as pto) --> pto pump ---> sickle bar hydraulic motor. just cut out the middle part.

It's two separate systems i was thinking of:

I want to mount the sickle mower on a tractor (actually on the end of a front loader, for trimming tops of orchard trees etc) and power it from the tractor's pump. Like this guy:
Tinkering on the Farm: A buzz cut for peach trees - YouTube

The hydraulic pump/PTO idea was for a separate, unrelated installation on a mini-truck. (Thought it would be nice to be able to power and run a few PTO-driven implements from the truck, using the "extra part" i didn't need any more from the original sickle mower system).

 

[oldgrayfellow]

It's two separate systems i was thinking of:

I want to mount the sickle mower on a tractor (actually on the end of a front loader, for trimming tops of orchard trees etc) and power it from the tractor's pump. Like this guy:
Tinkering on the Farm: A buzz cut for peach trees - YouTube

The hydraulic pump/PTO idea was for a separate, unrelated installation on a mini-truck. (Thought it would be nice to be able to power and run a few PTO-driven implements from the truck, using the "extra part" i didn't need any more from the original sickle mower system).

Just to clarify:
The original sickle bar mower system received power from a tractor's PTO, which ran a hydraulic pump on the mower. This hydraulic pump in turn ran the mower's hydraulic motor that actually operated the sickle.

What i want to do is take the mower's PTO-driven hydraulic pump out of the equation (and use my tractor's hydraulic pump instead) when i mount the mower on the tractor's loader.
I wanted to convert the leftover PTO-driven pump into a hydraulic PTO drive for the mini-truck.

 

[BHD]

you may need to figure out what the GPM is on the pump as well as on the Motor (or to be motor),

and how is the pump being powered, if it is by belt you will not be able to power much of any thing more than what the belt can handle, (unless your speeds are considerable different), then you may get some advantage,

I have an attachment on the combine, and the variable Hydraulics on this machine is ran by a belt to a pump, but if the attachment bogs down or binds the belt slips, (which in this case may be good), but just a heads up on the possible load one can get out of it,

 

[Taylortractornut]

Some hydraulic pumps can be run as motors. SOme pumps have check valves in side them and wont tolerate any kind of backflow, some will handle it the one way. I have a pump in the shop right now that a freind hooked up as a motor and burst a housing. You can get a hydraulic motor from Surplus center or Bailys hydraulics pretty cheap and save the PTO pump.

 

[SSdoxie]

Just to clarify:
The original sickle bar mower system received power from a tractor's PTO, which ran a hydraulic pump on the mower. This hydraulic pump in turn ran the mower's hydraulic motor that actually operated the sickle.

What i want to do is take the mower's PTO-driven hydraulic pump out of the equation (and use my tractor's hydraulic pump instead) when i mount the mower on the tractor's loader.
I wanted to convert the leftover PTO-driven pump into a hydraulic PTO drive for the mini-truck.

You will need another motor. You can power the pump with the engine, but need a motor at the PTO to receive the oil and power the PTO.

 

[Farmerford]

If the PTO pump is a gear type (Prince, for example) it will work just as well as an external gear type hydraulic motor: relatively inefficient, higher leakage than an orbital or piston motor, noisy, tolerant of contamination, and not particular about fluid viscosity. But since you already have the pump why not try it? As long as you have a relief valve for the "motor" circuit that opens at or below the "pump's" rated pressure it is unlikely you could hurt anything.