Proportioning Valve Questions

/ Proportioning Valve Questions #1  

California

Super Star Member
Joined
Jan 22, 2004
Messages
16,784
Location
An hour north of San Francisco
Tractor
Yanmar YM240 Yanmar YM186D
I'm replacing the power steering cylinder on the Yanmar YM186D and have run into some mysteries. This Power Steering kit was dealer installed when the tractor was new in about 1985, and shows no signs of any work until my present project. I have the PS install manual.

1) The 'Out' hose from the proportioning valve is attached to the opposite side of the proportioning valve compared to the PS install manual. That valve's input line is where it belongs, first thing in series from the hydraulic pump. I had expected that valve would be directional.

2) Even stranger, there's a second proportioning valve loose under the floorboard in series with the loader - I think. It's an oily mess under there and I haven't traced the spaghetti-bowl mess of hydraulic lines yet. Only that first proportioning valve, installed in its proper location, is shown in the power steering install manual.

3) Power steering steals all the power from the loader or 3-point below 1k rpm, I always assumed this was unavoidable. But if things are configured wrong I may be able to improve this, in particular by bypassing that second undocumented proportioning valve.

I should note the PS manual shows how to configure it if there is a loader, which I have, so that isn't a reason for variance from the manual's diagrams.

Comments???? Any ideas why a dealer would install that factory-authorized kit differently from its manual and add a second (expensive?) proportioning valve? :confused:
 
/ Proportioning Valve Questions #2  
The first valve in the pressure line should be or have the relief valve in it . I suspect one of the valves is a priority flow control especially if you have single valve providing flow to both steering and FEL. The priority flow should have a minimum of three lines connected to it.
One from the pump.
One to the steering unit
One to the FEL valve

If relief is in the same block you should then have a 4th to tank

If there is a circuit of schematic in the PS install manual post that and I am sure someone can assist you in identifying the components
 

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