Case IH PUMA 130, Service Manual

Page: 43 / 61

HYDRAULIC, PNEUMATIC, ELECTRICAL, ELECTRONIC SYSTEMS - PRIMARY HYDRAULIC POWER SYSTEM
BAIL07APH326ASA
20
Operation of the closed centre high pressure hydraulic circuit is as follows:-
The components in the high pressure hydraulic circuit are connected by their load sensing lines to the hydraulic load
sensing valve which controls the output of the hydraulic pump.
When the trailer brakes, remote control valves, hydraulic lift or front axle suspension (where fitted) are operating, the
load sensing valve on variable flow piston pump, compares the pressure in the component load sense line with the
output pressure of the hydraulic pump.
If pump output pressure is less than the combined pressure of the load sense line and spring force of the flow con-
trol valve, then pump output continues to increase. When circuit demand is satisfied pump pressure overcomes the
combined pressure of the load sense line and flow compensating valve spring. This moves the spool in the flow com-
pensating valve to the right, allowing control pressure oil to be directed to the variable flow swash plate servo piston,
which de-strokes the pump to adjust output to circuit demand.
High Pressure oil is fed to a subplate at the bottom of the remote valve stack where it is directed to the Trailer Brake
valve which has priority for safety reasons. The oil is then redirected to the Electronic Draft Control Valve and the
Electro-Hydraulic Remote Valves. Within the subplate is a pressure compensating valve which diverts the oil to the
low pressure system at a pressure of
18 bar ( 261.00 psi ).
High Pressure oil is also fed to the top of the Remote Valve stack through an end plate which incorporates a pressure
limiting valve and this supplies oil at
20 - 22 bar to the pilot line galleries in the Electro-Hydraulic Remote Valves.
Surplus oil from the charge pump to the variable displacement pump is fed past the 0.8 bar valve and boosts the
pressure in the lubrication circuit.
The trailer brake valve is located on the sub plate of the remote valve stack. The valve diverts oil pressure to the
trailer brakes whenever the brake pedals are depressed.
The trailer brake has absolute priority over other services in the circuit.
BAIL07APH327ASA
21
The remote valves are available as two, three or four valves per tractor.
The valves can be double-acting with float and kick out.
Double acting convertible to single-acting with float.
84479138A 06/06/2011
A.10.A / 15