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| Illustration 1 | g00292601 |
(1) Solenoid valve (2) Manifold (3) Valve spool (4) Bail (5) Bail cylinder (6) Push-Pull control valve (7) Push-Pull/Cushion-Hitch pump | |
Introduction
The push-pull hydraulic system gets oil from the push-pull/cushion-hitch pump (7) . The oil from the push-pull/cushion-hitch pump (7) is sent to the manifold (2) . The oil is then sent to the push-pull control valve (6) .
The solenoid valve (1) is used to control the push-pull hydraulic system. The valve spool (3) in the push-pull control valve (6) is moved from the normal spring loaded position when the signal oil from the solenoid valve (1) is sent to the valve spool (3) . The solenoid valve can be switched in two positions by the operator.
The operator can move the switch into the following two positions:
- Place the switch in the up position in order to enable BAIL RAISE .
- Place the switch in the down position in order to enable BAIL LOWER .
When the ignition switch is in the OFF position, the engine is not running and there is no output oil from the piston pump (7) . The solenoid valve (1) will be in the BAIL LOWER position and the valve spool (3) is in the BAIL RAISE. The solenoid valve (1) and the valve spool (3) are in these positions whenever the engine is not running. The solenoid valve (1) and the valve spool (3) cannot be moved until the engine is started.
When the engine is started, the oil from the push-pull/cushion-hitch pump (7) is sent to the solenoid valve (1) , the push-pull control valve (6) , the pilot control valve and the cushion-hitch levelling valve. The oil is sent to the solenoid valve (1) in order to provide pilot oil to the valve spool (3) . The oil is sent to the valve spool (3) in the push-pull control valve (6) in order to enable the BAIL LOWER. When the oil is sent to the valve spool (3) the oil is also sent to the cushion-hitch levelling valve and the cushion-hitch accumulators. When the cushion-hitch accumulators are recharged by the oil from the push-pull/cushion-hitch pump (7) to the pressure setting of the pump compensator valve, the push-pull/cushion-hitch pump (7) will reduce the pressure to the minimum output. Refer to System Operation, "Piston Pump (Cushion-Hitch)". The information is in this manual. Oil goes through the push-pull control valve (6) in order to control the bail (4) .
Starting the engine will produce a maximum flow from the push-pull/cushion-hitch pump (7) . The maximum flow from the push-pull/cushion-hitch pump depends on RPM. The pressure in the system will start to build up.
The solenoid valve (1) is in the BAIL LOWER. Pressure in the supply side of the solenoid valve (1) is the same pressure at the end of valve spool (3) . Valve spool (3) shifts when pump pressure reaches about 400 kPa (58 psi). When pump pressure reaches about 700 kPa (101 psi), valve spool (3) is fully shifted to BAIL LOWER position.