Hydraulic Pump compensation - VDPP - Variable displacement piston pump

The Milnor Single Stage press uses a variable displacement piston pump as a primary hydraulic pump.  This pump has the ability to regulate flow and pressure and is adaptable to a variety of motor horsepower selections.  

Replacement pumps are set from the factory for the most common motor horsepower (30 HP).  Some machines in the field may use lower horsepower motors. The installer is required to make adjustments on the horsepower compensator to accommodate the motor installed on the press.  If this is not done, a smaller motor may fail.  

The press controls allow for low pressure functions like ram up and can up / down.  These functions operate at approximately 800 psi and require less horsepower than a ram down command at full pump pressure and flow. The adjustments for max horsepower must be done when pressing a load under the ram. Be aware that the pump can require so much horsepower that a smaller motor will stall or be significantly overloaded.  

A new pump must be lubricated internally before starting or the pump will fail.  Fill the case of the pump manually to the topmost case vent plug before connecting the case drain hose.     

The pump has a 2 stage horsepower compensator adjustment.  Stage 1 is used for higher flow and stage 2 at higher pressure.  The installation and maintenance manual describes how to set the compensator.  You must check the amperage draw of the motor to ensure operation below the full load amps of the motor.  When pressing the motor will briefly run over full load amps and then settle to a lower amperage draw as the pressure builds.    

The most common pump used is a 80cc VDPP.  The notes for this pump are attached.  
Other pumps 45 and 110cc, are compensated at differing values.  The motor MUST be checked for amp draw after installing a new pump. Adjustment may be needed to prevent motor failure.  

Instruction Part Number: H7E550466
Milnor Part Numbers: 27E550466, 27E550566 and 27E550766

LUBRICATION!

These pumps MUST be internally lubricated with hydraulic oil before startup. The case of the pump has 2 ports for the case drain. Milnor presses use the highest port as a return to tank. This port must be filled with fluid before installing the hose. In addition, the pump inlet and outlet fittings should be filled with oil before startup. Do NOT remove any pump components (compensators) to lubricate the pump.

HORSEPOWER SETTINGS:

The pumps are compensated from the factory. However, your motor may not be the same size as motors used in production today. So, you MUST check current draw on your motor while pressing and confirm that the pump is not overconsuming horsepower from the motor. These pumps can burn up a motor if not compensated properly.
For example, the 27E550566 is compensated from the factory at 27 HP. This works fine for a 30 HP motor but some presses have a 20 HP motor. If this is your case, you must adjust the horsepower compensator to draw less than 20 HP so the motor does not overload. You need an amp meter and wrenches to adjust the compensator. Instructions are in the Milnor Press service manual.
You can adjust the pump to draw 5 to 10 percent less than full load amps from the motor to help extend motor life.

27E550566 Kawasaki Hydraulic pump

This pump is capable of being coupled to motors of various horsepower. The pump is set at the factory to a horsepower compensation of approximately 27 horsepower.
If you are connecting this pump to a lower horsepower (20HP) motor then you must lower the compensator adjustments before running the motor. This adjustment is done by turning both compensator adjustments counterclockwise. Afterward the compensator adjustments can be brought in line with the horsepower of the motor by using the setup guide found in the Milnor service manual.
The theoretical minimum horsepower required by the pump is 17 HP with the L spring set. The maximum theoretical horsepower is 30 HP. Milnor has used both 20 and 30 horsepower motors on this pump depending on the model of the single stage press.

Topics:
Kawasaki, Hengli, Linde
How to adjust the HP compensators. How to check amp draw on the motor.    
How to prime the pump.
Hengli 80cc pump drawing attached