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Mid-East Nebraska | This from JD Service Advisor.
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Reference 270-20-002, Hydraulic System Operation
LV11536-UN: Hydraulic System Operation
LEGEND:
A - Triple Mid-Mount Control Valve (Optional)
B - Dual Mid-Mount Control Valve (Base)
C - Triple Deluxe Rear SCV (Optional)
D - Hitch Valve Inlet Housing
E - Relief Valve Return to Transmission Case
F - Load Sensing Valve
G - Main Relief Valve
H - Load Sensing Relief Valve
I - Raise Valve
J - Hitch Valve Inlet Housing
K - Hitch Relief Valve
L - Rockshaft Cylinder
M - Suction Screen
N - Filter/Manifold
O - Hydraulic Filter
P - Filter Bypass Screen
Q - Suction Line
R - Hydraulic Pump Housing
S - Steering Pump
T - Main HydraulicPump
U - To Steering, Brakes, and Transmission Lubrication
The hydraulic system contains two hydraulic pumps which are contained in a single housing. The steering pump (S) is the rearmost pump and the main hydraulic pump (T) is the forward pump. The steering pump (S) provides fluid power for steering, brakes, and transmission lubrication (U). See Section 260, Group 20 for Steering System Theory of Operation.
The main hydraulic pump (T) provides hydraulic power to the rockshaft for hitch operation and to the optional selective control valves, if equipped. The hitch is catagory 2/1 with draft-sensing through the center link.
The hydraulic system uses an open-center design. This means that low-pressure oil flows continuously through the valves, lines, and back to sump as long as the valves are in a neutral position.
The transmission case of the tractor serves as a reservoir sump for hydraulic oil. Proper level must be maintained for adequate transmission lubrication and oil supply to the hydraulic pumps.
The engine gears drive the hydraulic pump. Oil moves from the transmission case through suction screen (M) and hydraulic filter (O) in filter/manifold (N) through suction line (Q) to the inlet side of the hydraulic pump housing (R).
Oil flows from outlet side of the pump, through pressure line to hitch valve inlet housing (J). The load sensing valve (F) in hitch valve inlet housing (D) directs priority oil to hitch raise valve (I). When in NEUTRAL, the load sensing valve directs oil to the selective control valves.
Tractors may be equipped with either an optional dual (B) or triple (A) mid-mount control valve and single, dual, or triple deluxe rear SCV (C) . A main relief valve (G) limits hydraulic system pressure to mid-mount selective control valves and rear SCV to a range of 18 995—19 685 kPa (190—197 bar) (2755—2855 psi). A load sensing relief valve (H) limits hitch system pressure to a range of 18 995—19 685 kPa (190—197 bar) (2755—2855 psi). A hitch relief valve (K) limits pressure in the rockshaft cylinder to 23 500 kPa (235 bar) (3400 psi). Return oil flow from the rockshaft cylinder (L) and relief valves is returned directly to relief valve return to transmission case (E). All returned oil flow from hitch valve inlet housing, mid-mount selective control valve, and rear SCV is returned to filter/manifold (N).
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Open center PFC hydraulic ????
