Marine Technology Group

ASD Control Systems

EATON PRESSURE COMPENSATED
AND
 LOAD SENSE HYDRAULIC PUMPS  

Pressure Compensated and Load Sense pumps offer an ideal method for smooth, quiet anbd responsive control to Arneson Surface Drives.

These pumps are an efficient method for the transference of hydraulic work.  On Pressure Compensated systems, a small oil cooler is required in the case drain line from the pumps.  In a Load Sense system, no oil cooler is required.

EATON SERIES 70422 AND 70423
PRESSURE COMPENSATED PUMPS

Constant Pressure and variable flow

Pump is in high-pressure standby mode when system is not actuated

Pump automatically adjusts output flow to meet system requirements

Allows for simultaneous operation of multiple functions

Fast response to system pressure or flow requirements

Closed Center systems are ideal when the hydraulic system requires several separate functions to operate simultaneously. When used with a closed center control valve, and the hydraulic system is not actuated, the pressure compensated piston pump will remain in the high pressure standby mode at pressures up to 210 bar [3000 PSI]. The pump will maintain the high pressure and zero flow as long as the system is not actuated. When a hydraulic function is actuated, the pressure compensated piston pump senses the change in the demand for flow and adjusts the pump displacement to increase the flow required while maintaining full system pressure up to the control valve. The pump will strive to maintain maximum system pressure to the control valve under all working conditions. The pump will adjust output flow to meet any change in system flow requirements. The pump will maintain full system pressure as long as the system flow requirement does not exceed the total flow capacity of the pump. With constant system pressure and a known working pressure, each function can be independently orificed to provide simultaneous operation and precise cycle time of individual circuits within the hydraulic system. If the hydraulic system stalls out under a load, the pump will go into the high pressure standby mode until the load is overcome. This prevents a large volume of pump flow from passing over the system relief valve as happens in the typical open center hydraulic system.

EATON SERIES 70422 AND 70423
LOAD SENSE PUMPS

Variable pressure and variable flow

Pump is in low-pressure standby mode when system is not actuated

Pump automatically adjusts output flow and pressure to meet system requirements

Allows for simultaneous operation of multiple functions

Fast response to system pressure and flow requirements

One pump may be used instead of multiple pumps

The Eaton Pressure-Flow Compensated Piston Pump senses pressure and flow requirements and provides only flow and pressure required, plus 14 bar [200 PSI], to operate the compensator. The low pressure standby, 14 bar [200 PSI], prevents excessive heat buildup in the pump and eliminates unnecessary horsepower drain. The pressure-flow compensated load sensing system is noted for its high efficiency and controllability. The following two systems demonstrate the general load sensing concept.

When used with a closed center load sensing control valve, and the hydraulic system is not  actuated, the pressure-flow compensated piston pump will remain in the low pressure standby mode at only 14 bar [200 PSI]. When a hydraulic function is actuated, the pressure-flow compensated piston pump senses the demand for flow and adjusts the pump displacement to increase the flow required at only the pressure required to operate the circuit, plus the 14 bar [200 PSI] to operate the compensator. The pump will strive to maintain the flow required, at only 14 bar [200 PSI] over the pressure required, under all working conditions of the system. A load sensing line is connected from the load sensing control valve to the pump to feed all the circuit requirements to the pump compensator. The pump will respond to the highest pressure of all the circuits and provide the total flow required to operate multiple circuits. A load sensing line bleed orifice is preferred in the load sensing control valve to prevent high pressure compensation of the piston pump when the control valve is returned to neutral. If the load on the system produces a hydraulic pressure that is equal to the high pressure setting of the compensator, the pump will go into high pressure standby mode and destroke until the load is overcome or the control valve is returned to neutral. This prevents a large volume of pump flow from passing over the system relief valve as Compared to the conventional open center hydraulic system. To achieve true simultaneous operation of individual circuits, a flow compensator should be incorporated in each circuit, otherwise the system will send the most flow to the circuit with the least resistance. In many cases, the heat exchanger may be eliminated because of the systems higher efficiency.

70422 AND 70423 SPECIFICATIONS

Dimensional and Interface Data

Eaton Model 701222, 1.6 in³/r [19 cm³/r]

Eaton Model 70422, 2.32 in³/r [38 cm³/r]

Eaton Model 70423, 2.77 in³/r [45 cm³/r]

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Hydraulic Pumps