The Basic Closed Circuit
Hydraulic lines connect the main ports of the pump to the main ports of the motor. Fluid flows in either
direction from the pump to the motor and back. Either of the hydraulic lines can be under high pressure.
In pumping mode the position of the pump swashplate determines which line is high pressure as well as
the direction of fluid flow.
Case Drain and Heat Exchanger
The pump and motor require case drain lines to remove hot fluid from the system. The pump and motor
drain from the topmost port to ensure the cases remain full of fluid.
The motor case drain can connect to the lower drain port on the pump housing or it can tee into the case
drain line upstream of the heat exchanger. A heat exchanger with bypass valve cools the case drain fluid
before it returns to the reservoir.
H1 Single Pumps Closed Circuit Pictorial Diagram
P104 464E
Charge
Pressure
Relief
Valve
Loop
Flushing
Valve
To Pump
Case
To
Motor
Case
Servo Control
Cylinder
Variable
Displacement
Pump
Input
Shaft
Pump Swashplate
Pressure
Limiter
Valve
Charge Check/High Pressure Relief Valve
Synchronizing
Shaft
Output
Shaft
Motor Swashplate
Bent Axis Variable
Displacement Motor
System Pressure
Servo Pressure
Charge/Low Loop Pressure
Suction/Case Drain/
System Return
Charge Filter
Charge Pump
Reservoir
Heat Exchanger
Bypass Valve
Displacement Control
Heat Exchanger
Charge Check/
High Pressure Relief Valve
Service Manual
H1P 045/053/060/068 Axial Piston Single Pumps
Introduction
©
Danfoss | June 2020
AX152886481964en-000405 | 9