Hydraulic pump ?s for mounting a Massey Ferg 220 Backhoe on my TD-6

My ? is this: I need a hydraulic pump with more power than the TD-6's engine mounted unit, and I don't know which would be best. I would like to use as much of the 34 hp that the TD-6 develops, if new, to run the backhoe pump. This means I need to optimise for the flow vs. pressure that the MF 220 Backhoe was designed for. I've come to understand that pressures where limited to 1500 psi or less on older hydraulic equipment, to which this certainly applies. However, all of its plumbing, o-ring connections, etc. and cylinders, look like stuff that would be rated for higher pressures. I'd love to know what psi and flow I should target the MF 220 for. I believe this backhoe was made primarily for the MF 200 crawler, does anyone know what its hydraulic pump specs were?

A this point, with what I know my solution is this: Given about one horse power required per 1 GPM flow at 1500 psi I think a Prince 21-spline 40 GPM 1000 RPM PTO pump would work perfectly but I am not sure. If I connect this pump through a PTO extension shaft (6-spline 1 3/8" female to 21-spline 1 3/8" male)connected to the TD-6 tranny's PTO output shaft which turns at about 850 RPM, the output of the 1000 RPM rated pump will decrease 15% to 34 GPM. At this flow I might be able to get 1500 psi. If I set the reliefs to 2000 psi or so, I am thinking that when I bog the hoe down, my engine will likewise bog, which will increase my torque, and therefore my psi will go up as my RPM and flow drops off. This will achieve good breakout force while having fast cycle times.

Does anyone know if I am thinking straight? Please inform.
And thank you very much, in advance.

As Wardner said, I would recommend installing a front mounted gear pump driven by the crankshaft. Depending on the age of your TD-6, the operating RPM of the engine could be as low as 1400 RPM. For longer engine life, I WOULD NOT maximize the output of the pump to the maximum horsepower of the engine.
There is one important aspect of the directional control valves on the backhoe that must be answered. Are the valves open center or closed center? If the valve bank is open center, a fixed displacement gear pump will work. If the valve bank is closed center, a variable displacement pump (axial piston pump) will have to be used.
I would recommend a 5 cubic inch per revolution fixed displacement gear pump if the valve bank is open centered. At 1400 rpm's, the pump will put out about 30 gallons per minute. You are correct in that the torque of the engine will drive the pump at a higher PSI (2000 to 2500) at a lower RPM but the engine is maxed out and the design of the hydraulic pump system is poor at best.
Hydraulic tank size should be close to the pump output to maintain proper hydraulic oil temperature. Suction and pressure hoses from the pump should be properly sized for the pump capacity to maintain minimal oil velocity and reduce friction and vecosity losses. Good luck.

Ray

The MF 220 valves are open center. And thanks for pointing out what should have been obvious to me, don't kill my tractor. I will scale my desired hp's back so I don't overtax my TD-6 engine.

I have solidified on using a pump off of the upper tranny shaft on the rear of the TD-6 as it provides a very secure, protected, and easily serviced location on a TD-6. Now I need to find the perfect pump:)

I have solidified on using a pump off of the upper tranny shaft on the rear of the TD-6 as it provides a very secure, protected, and easily serviced mount on a TD-6. From what you said, PTO mounts must be more rearward on most tractors for on my TD-6 a front mounted pump would be much, much more prone to damage. Wouldn't look as cool either:)

Thanks for responding though.

I have solidified on using a pump off of the upper tranny shaft on the rear of the TD-6 as it provides a very secure, protected, and easily serviced mount on the TD-6. From what you said, PTO mounts must be more rearward on most tractors for on my TD-6 a front mounted pump would be much, much more prone to damage. Wouldn't look a cool either:)

Thanks for responding though.