Danfoss Servo piston replacemnet Installation guide

Piston Ring

Service Kit Instructions

Series 42 Servo piston replacemnet

PURPOSE: Special precautions must be followed when installing a servo piston into a Series 42 pump.

Sharp edges on the interior servo bore will damage the piston sealing rings. This bulletin is intended to give instructions for installation of the servo piston on a Series 42.

PROCEDURE:

Note: Once a servo adjustment seal lock nut has been removed, it should be discarded and replaced because it will lose its sealing properties. The nut is included in the overhaul seal kit.

1. Lubricate the piston rings with a

piston ring has already been placed on the neutral adjust screw end of the servo piston.

2. Slide the servo piston through the housing bore, inserting the non neutral

that the cavity for the servo piston/ swashplate bearing assembly faces the center of the housing. Push the piston through the housing just far enough so the other piston ring may be installed, but do not let the neutral adjust screw end piston ring pass into the interior servo bore.

Note: It is important to not twist or stretch the piston rings too much, as looseness may cause piston ring damage when installing the servo piston. Do not distort the piston rings any more than is necessary. After installing a piston ring, allow it to contract for a few minutes prior to inserting the piston into the housing bore.

5. Replace servo covers and gaskets as outlined in the Series 42 Repair Manual (11007277).

Note: Neutral setting adjustments must be made to any pump that is disassembled. The seal nut must be torqued as outlined in the Series 42 Service Manual (520L0638), once the neutral adjustments have been made.

Servo Piston

Swashplate Bearing Assembly

Neutral Adjust Screw

Seal Nut

3. Place the second new piston ring on the servo piston. Allow the piston ring a few minutes to ‘relax’.

4. Push the servo piston back through the bore so that the neutral adjust screw

ing. Do not allow the piston ring to show again.