Application
A hydraulic circuit may be powered at different times by a high-pressure, low-flow pump and a low-pressure, high-flow pump. This two-pump circuit configuration eliminates the need for a relatively expensive high-pressure, high-flow pump and also saves energy. High Low systems are used with combinations of two (or more) pumps to give high flow at low pressures and high pressures at low flows. The system bypasses the flow from the LP pump(s) to tank at a preset pressure. This allows for pump selection to give, for example, rapid advance and high power compaction with the most economic usage of system components and energy requirements.
Application areas are High Capacity Presses, Cotton Baling Machines, Scrap Baling Machines, Car Crushers.
Operation
Pump inlet into the system is combined to give maximum flow at low pressure. When the load pressure increases to the set level, the high flow (low pressure) pump is bypassed from LP to tank via the dedicated Unloading Valve (2) allowing nearly all the system power to be used for the high pressure pump (See graph for the pressure drop of dumped flow). The system relief valve provides protection by limiting the maximum pressure in the system line.
This is a self contained system including four replaceable cartridges with full adjustment through their respective ranges. The compact nature of the hydraulic system reduces the need for bulky valves and piping. The system can be used for flows up to 400 lpm! (250 lpm high pressure and 150 lpm low pressure pump) Pressures up to 350 bar can be obtained using the system. The HIC comes with an on board pressure switch for electronic signalling of the pressure in the outlet line.
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