Series 51-1 Motors - Danfoss 51 Series Service Manual

Service Manual
Series 51 and 51-1 Motors
Introduction
Series 51 motor cross section
Hydraulic proportional
control
4-way
valve
Servo
piston

Series 51-1 motors

8 | © Danfoss | March 2016
The 4-way spool valve shifts the servo supply pressure to change the motor displacement. The servo
supply pressure can be external or internal.
Minimum displacement
liter
Series 51-1 motors feature simplified end cap and control components. The servo piston in the Series
51-1 has a differential area of 2 to 1. The connecting joint is designed to decrease the overall length of the
motor.
The Series 51-1 control feeds servo pressure directly to the servo piston. Low system loop pressure for
two-position controls, and high system loop pressure for pressure compensating controls actuates the
servo piston.
Rotating hardware and housing components are common between Series 51 and Series 51-1.
Valve segment
Speed pickup ring
Bearing
plate
Tapered roller bearings
Speed sensor
Piston
Charge pressure relief valve
SAE-Flange
Synchronizing shaft
P101 173E
11008567 | AX00000013en-US0202