3rd Function on Mahindra 4350

irsmun · Oct 22, 2013

So to clarify...since I had fluid flow when I loosened the fitting, it does indicate PB since no cylinders were engaged at the time?

Understanding how the valve is designed helps too. It looks like the #1 is last in line of the valve chambers. PB is last priority in the valve right?

Does the descent knob indicate PB? In other words, in order for it to function does it need to be set in line between the 3pt and the pressure send?

If this line is indeed the PB what is the other line that also goes directly to the rear?

Sorry if these questions are simple... but so is my understanding at this point. I appreciate your experience and feedback. Thank you.

I really wish the machine came with more detailed construction diagrams and info, but perhaps those are reserved for the mechanics and engineers.

J_J · Oct 22, 2013

One of those lines is the return line to sump/tank.

To test that, loosen or remove the line #2 at the rear and there should be no fluid flowing unless a cyl is moving.

varmint · Oct 23, 2013

This is a fun thread to follow, in that I only dream of having additional hydraulic functions on my little, old B8200. When ever I use the rear blade, and hop on and off to adjust tilt or angle, I think about how sweet two more cylinders would be, but of course, not really practical on such a tractor. Still, I enjoy learning a bit about how I "could" do it if I was crazy enough.

irsmun · Oct 23, 2013

The transmission and the hydraulic tank are common. Who knew? Maybe this is par for the course on tractors...but this is my first tractor so its news to me. Given that info it does add more evidence that the green (#2) hose is the return to the trans and the #1 hose is PB. I am going to do the final test JJ mentioned and loosen the #2 hose to check for flow.

Just so my intentions are clear, I plan on following this thread out all the way through the install...so don't get irritated with me. I'm going to ask questions...dumb ones even. Better to ask than to break something.

irsmun · Oct 23, 2013

MtnViewRanch, how high should I go on the valve flow? Should I surpass the 10.9 gpm rating and if so how much is acceptable?

J_J · Oct 23, 2013

You only need to meet the pump flow.

The 12 GPM subplate and valve I posted above will be more than satisfactory for the tractor flow.

Even a 10 GPM valve will work as most people will not run the engine at full throttle all the time.

Engine rpm is related to pump flow.

You gain nothing by using a larger valve.

What if the other valve in the series path are 10 GPM valves, would you use a larger valve.

The size of the valve ports will allow a certain flow..

http://www.insanehydraulics.com/library/hosesizing.html

Pull the yellow dot down to the flow in GPM, and you will see the port size necessary for that flow, at the flow velocity.

irsmun · Oct 23, 2013

Ok, but how high can I go? I am shopping for valves (and prices) and I have found a 16.8 gpm at 4500psi for $110.

Northman Fluid Power Hydraulic Directional Control Valve – 16.8 GPM, 4500 PSI, 3-Position, Double Solenoid, Open Center Spool, 12 Volt DC Solenoids, Model# SWH-G02-C3-D12-10 | Power Solenoid| Northern Tool + Equipment

The subplate is $40.

Northman Fluid Power Single-Station Subplate — NFPA D03 Pattern, 3/8in. NPT Side Ports, Model# M02-03-S-2 | Control Valve Accessories| Northern Tool + Equipment

Would these work? I looks like the only difference is that its 3/8 for the tank and pressure. Would that affect flow to the 3pt?

J_J · Oct 23, 2013

The valve you posted is an open center valve for a hyd motor or cyl and in neutral, the work ports are common.

I can't find the valve for you from Northern.

You need a tandem spool so the cyl are locked in neutral.

The solenoid valve from Baileys will work.

irsmun · Oct 23, 2013

I am ok with the bailey valve...its the subplate that made me gasp. Its over twice the price of the others. I was looking to stay under $200 for both and the more the better. I still have to price a control grip, the hoses, some 90's and a pair of quick connects.