Help with choosing correct hydraulic motor..

[Garrett2006]

Looking to convert an older 3 point hitch 5 rotary cutter to quick attach & use my rear hydraulic remotes to run it on the front end loader. I already have all the parts for converting the 3 point to quick attach. Needing help figuring out the correct hydraulic motor to use. I値l be keeping the current PTO gear box and mounting the new hydraulic motor onto a base & connecting the to shafts. The specs are below.

Tractor rear remote - 12.4 GPM
Tractor hydraulic Pressure- 2277 PSI
Rotary cutter gear box rating - 40 HP
Rotary cutter RPM rating - 540 RPM
Thinking the motor needs around 389 ft lb of torque

Tractor is a Massey Ferguson 2706E

If anyone has any thought or experience on this please chime in. Not looking to cut the world cut with this cutter just small black jacks and around some ponds. Small limbs in roads and shooting lanes etc...been looking on surplus center website, but really not wanting to order the wrong motor. Also, would possibly like a motor that has a cushion relief valve built into the motor, but if not available I can just add one in the lines.

Anyone willing to help out on this?

Thanks!

 

[oldnslo]

A motor with displacement of 5 - 5.25 cubic inches/ revaluation will provide the desired speed with 12.4 GPM flow.

Cushion relief is usually line mounted

 

[ptsg]

SurplusCenter has some good calculators for that kind of stuff: Surplus Center

Don't forget to add a Motor Relief Bypass Valve so the motor coasts to a stop when you let go the remote lever. Otherwise the momentum will most like blow the motor seals.

Or just a couple of Tee's and a check valve between the ports.

 

[Garrett2006]

Thanks. Isn’t a motor relief bypass value the same as a cushion relief value?

 

[agjones]

More or less yeah. Might be built in the circuit already. Check your diagram.

 

[RNeumann]

Unfortunately this type of project typically turns into an expensive can of worms. The CUTs weren’t intended to run the hydraulic motors you need. Between the PTO HP needed and the cooling needed you are going to be chasing this project a bit.

Good luck and keep us posted. It would be interesting to a CUT hydraulic motor success story! ..........and I’m not talking a PHD that digs a few holes. I’m talking a mower or blower that runs continuously for long periods.

 

[Dave M7040]

I am with RNeumann. Waste of time and $.

First you likely don't have 12.4 gpm as your tractor has power steering. Usually, some of the pump output is controlled thru a priority valve to feed the steering before anything else.

Next, your tractor is an open center system. The loader valve likely feeds the rear remotes and 3 pt using a power beyond port.

What this means is that any time you adjust your loader, the flow to the hydraulic motor will be dramatically reduced or cut off.

Heat.... your tractor was not made to get rid of the heat a continually running hydraulic motor will generate.

If you really must have a front mounted cutter, install a gas engine on it.

Dave M7040

 

[agjones]

Don't want to pile on... But heat and geometry are going to be the biggest enemy of this project. I'd be surprised if you have 12gpm to the remotes. But even if you do, they may not be intended to service long running implements like mowers.

You can see the pto to hydraulic mods I've done in the power trac forum. But that is on a machine meant to work an attachment out front, the power trac 1850 and 425. The implement side is simple enough. But the loader arms are a bit of an Achilles heel. Many to scoop, tote dump more than anything else.

Confirm the flow and heat plan and see if you want to go for it.