D7, D8, Da, Dc Controls; Operation; General Description; Pressure-Reducing Valve - Danfoss 51 Series Service Manual

Service Manual

D7, D8, DA, DC Controls

Operation

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Series 51 Electrohydraulic Proportional Controls Service Manual

General Description

The D7 and D8 controls consist of a ported housing with an electric pressure-reducing valve, a pressure
compensator override valve (PCOR), and an optional hydraulic brake pressure defeat (BPD) spool. For
these controls, there must be external servo supply pressure fed to the M5 port (25 bar [363 psi]
minimum, 50 bar [725 psi] maximum).
DA and DC controls include an electric brake pressure defeat option.

Pressure-Reducing Valve

The pressure-reducing valve uses servo supply pressure for signal pressure. It varies this pressure
electrically and feeds it to the end of the F32 4-way valve. With signal current below the threshold setting,
the motor defaults to maximum displacement. An increase in signal current shifts the motor
displacement from maximum to minimum.
D7, D8 Control
F32
G420
G42
G38
M24
M23
M23A
M22A
M22
M24A
M24
This pressure-reducing valve coil is high current. It has an input range of 640 mA to 1188 mA (12v) or 320
mA to 594 mA (24v).
The D7 solenoid is 12 volt. The D8 solenoid is 24 volt. Both are fitted with AMP Junior Timer connectors.
11009448 • Rev BA • July 2014
F324
G36
G38
G42
M24
T4
M24
M1
M15
M151
M150
T6
N32
M21
M20
M18
Z*
M16
M14
P101 919