Sauer Danfoss 51 Series Manual page 5

HYDRAULIC PUMP GROUP 3025
Type EQ electrohydraulic proportional control (Fig. 2)
consists of a valve block and pressure control pilot
(PCP) valve mounted on the multi--function block. The
valve block incorporates a pilot piston with centering
springs. A pin transmits force from the pilot piston to the
control spool in the end cap. Feedback springs and a
threshold spring are installed in the end cap. These
springs function similar to the HS control. Servo
pressure may be supplied from an external source or
internally by the shuttle spool in the multi--function block.
An external pilot pressure source is connected to the
inlet of the PCP valve, which produces differential pilot
pressures proportional to the current through it. These
pressures are applied to the pilot piston. The operation
of this control is similar to that of the HP Control, with the
Figure 2. EQ Control Components
motor displacement being proportional to the current
through the PCP valve. An increase in current above
the threshold current will result in a decrease in motor
displacement, while a decrease in current will result in
an increase in displacement.
3025- - 9A, Page 5