HYDRAULIC SYSTEM
ME12002
Valve Structure
Figure 3-88 Negative Control Valve Components 1 5,6 7 10 611 13 14 15 102
System path Pump regulator canal Opening Tank line Pressure limiting valve Valve washer Spring Valve housing Casing
Stand-by pump: approximately 6 gpm (21 L/min). Stand-by pressure: approximately 464 psi (32 bar).
Pressure limiting valve (611) consists of valve washer (13), spring (14), valve housing (15), and casing (102). See Figure 3-88 and Figure 3-89. Center bypass hydraulic fluid pressure increases path (3) pressure PN until the fluid arrives at the pre-set pressure of spring (14). When the fluid arrives at the pre-set pressure of spring (14), hydraulic fluid in path (3) opens valve washer (13) and flows into tank line (10). See Figure 3-88 and Figure 3-89.
Figure 3-89 Negative Control System Function For a larger view of Figure 3-89, see Figure 3-87 on page 107.
In the unloaded state, rear pump (28) hydraulic fluid flows through path (2), opening (9) and tank line (10) to the tank. Opening (9) reduces all discharge, increasing path (3) pressure PN to maximum level and destroking rear pump (28). This minimizes rear pump (28) tilting angle and discharge. See Figure 3-88 and Figure 3-89.
909768/BP1207
108
Printed in U.S.A
