Threshold And Ramp Springs - Danfoss 51 Series Service Manual

Service Manual
Introduction
10
Series 51 Electrohydraulic Proportional Controls Service Manual

Threshold and Ramp Springs

A threshold spring and ramp spring(s) act on the opposite end of the 4-way valve. The threshold
adjustment screw (S100) varies the threshold spring force. This changes the signal current required to
move the 4-way valve and start the change in displacement. The S10* ramp spring(s)—two used in 160 cc
and 250 cc motors and one used in 80 cc and 110 cc motors—increase the force on the 4-way valve as
the servo piston moves toward minimum displacement. This provides a motor displacement
proportional to the variable input signal current.
The control-operating threshold (the signal current or force when the motor starts to shift) is adjustable.
Adjust it using the S100 adjusting screw in the motor's end cap.
Changing ramp spring force requires replacing the springs. There are several spring rates available.
Optional orifices may be installed at several locations to regulate shift speed. Refer to the Model Code for
your motor for details.
Ramp Springs
J50
S100
(includes J30)
P101 909
S20
S10*
S10
160cc and 250cc
S10*
80cc and 110cc
J30
J10*
J20
11009448 • Rev BA • July 2014