IMPLEMENT AND STEERING HYDRAULIC SYSTEM CONTINUED
Constant flow is achieved when the force of the pressure of the pump supply in passage is equal to the sum of the
force of the springs and the signal pressure in the signal line. The forces on both sides of the margin spool will be
equal. The equal forces move the spool to a metering position. The metering of the margin spool provides a
stabilized system with constant flow.
As the signal pressure in line decreases, the force on the left of the margin spool is greater than the sum of the
force of the signal pressure and the force of the springs. The decrease in signal pressure causes the margin spool
to move to the right. The spool movement allows pump oil pressure to flow through passages and to the large
actuator piston. The large actuator piston will decrease the angle of the swashplate which decreases pump output.
As pump output decreases, the pressure on the left of the margin spool decreases. The decrease in pressure
allows the margin spool to move into a metering position again.
Figure 17. Pump and Compensator Operation (Constant Flow).