H0015 High Speed Unloader Valve Hydraulic Logic For MK6, SB30 and SB33 Integrated

System Operation

The tandem pump delivers oil to the high speed load sensed unloader valve, where the two flows can be combined to give high speed operation, or split to give low speed with the second pump flow returning to the oil reservoir.

LOW SPEED / HIGH PRESSURE Mode

In high speed the two oil flows are combined to give a total oil flow of 120l/m. To prevent the engine from overload the working pressure is reduced to 140bar (2000psi).

The pressure limiting is done by opening valve (3) and allowing L/S pressure to be limited by relief valve (5.2).

Increased flow occurs when the high speed valve cartridge (4) is energised allowing the 2^nd pump to enter the circuit

DUMP VALVE Optional

Also fitted to this valve may be a solenoid operated dump valve that is activated by the joystick controllers and the emergency stop buttons. This is an OPTION for higher levels of safety required for dangerous goods CE machines and PTO Versions.

When the valve is in the de-energised condition load sensed (LS) oil is dumped to tank. When the valve is energised the LS line is blocked to tank therefore allowing the hydraulic system to operate.

General Information

The low speed mode only applies to the lifting arms. The stabiliser legs are always in high speed irrespective of the position of the high/low speed selector mode switch.

When the dump solenoid is de-energised it is fail safe to dump L/S pressure.

When the High speed valve (4) and shutoff valves (3) are de-energised they return to low speed / high pressure therefore allowing the operator to continue operation with heavy containers.

Following is a summary of the logic and function of the "High speed load sense unloader valve".

High Speed Load Sense (LS) Unloader Valve Logic