Hydraulics Question

[clemet 146]

I just picked up a '73 12 automatic, and have gone through everything and cleaned it up, changed fluids, etc....  It came with a spare new lift cylinder, and I am thinking about making a 3 point to replace the sleeve hitch.  I am wanting to use the lift cylinder to raise and lower the 3 point which I have planned out in my head, but I want to be able to control it independently.  Looking at the spool valve that is on it to control the hydraulics it appears as though I can just remove the return line from the spool valve body, and bolt another spool to it, and then put the return back on.  I don't really want to tear it all apart only to find out it won't work since I am still using the mower this year (don't want to push mow while it's down).  I am wondering if anyone has tried this yet or am I better off just buying a 2 spool valve body and completely replacing the factory one?  If I have to replace it completely which type of valve do I need?

[KC9KAS 4,741]

@clemet 1st of all,

I added another spool valve on a GT-14 to make the 3pt lift work independent of the mid lift.

I see no reason that adding another valve to your tractor for a 2nd cylinder wouldn't work.

After the additional cylinder, be sure to check the fluid level in the rear end.

Oh, and most importantly,

[clemet 146]

@KC9KAS

 

Pictures are in this thread

, and here are some more.  The piece circled in yellow is what I was referring to about removing and adding a spool then bolting it back together.

 

 

Edited September 11, 2016 by clemet

[wallfish 17,112]

The use of a spool valve with a power beyond port is recommended for using valves in series. (But the use of a one way check valve might solve the back pressure issue).

http://www.baumhydraulics.com/files/infobuild/terms_hydraulic_control_valve.pdf

 

Since you need another valve anyway, use one with power beyond plumbed in front of the existing valve.

[clemet 146]

@wallfish  I was just looking at this one.

http://www.surpluscenter.com/Hydraulics/Hydraulic-Valves/Directional-Control-Valves/2-SPOOL-8-GPM-PRINCE-MB21BB5C1-DA-VALVE-9-7862.axd

 

It will do power beyond, and I would just replace the one that is already on the tractor completely to make mounting easier.

[wallfish 17,112]

Even better, you can always use the PB port to add another circuit later on with the old valve, if need be.

[clemet 146]

I was also trying to find out if over filling the trans will cause failure.  Basically can I add an extra reservoir inline with the valves so that I have more fluid, or will it hurt the transmission?

[wallfish 17,112]

No need for any extra fluid after the new lift cylinder is filled, the only difference in fluid level (from using a double acting cylinder) in the reservoir will be the volume of the rod. Since fluid pushes out one side as the other side is filled, the rod takes up space in one side only.

Plenty of calculators online to figure that volume but it's going to be small enough not to worry about. 

Make sense?

[Digger 66 3,488]

Welcome & COOL EXHAUST ! 

Never seen that before . 

Edited September 11, 2016 by Digger 66

[R. L. Addison 299]

I'm going to use a "D" series valve on my second rear lift unit.