TM 5-2410-240-23-1
0011
IMPLEMENT HYDRAULIC SYSTEM CONTINUED
Control Valves
00011
1. Blade Angle
The blade angle circuit will have the highest signal oil pressure in the hydraulic system when it is the only hydraulic
circuit in operation. When the operator rolls the roller switch to the ANGLE RIGHT position, pilot oil enters the
control valve through the port (Figure 7, Item 19) and pilot oil from the proportional solenoid valve flows into the
passages (Figure 7, Items 16 and 12). The spool (Figure 7, Item 10) moves to the left when the pilot oil overcomes
the force of the spring (Figure 7, Item 11). Pump supply oil then flows from the passage (Figure 7, Item 15) around
the spool to the feeder passage (Figure 7, Item 17) and then to the pressure compensator valve (Figure 7, Item 7),
where it flows into internal passages. As the pressure compensator valve moves upward, a cross-drilled passage
opens to an internal passage in the valve. In turn, some of the hydraulic oil flows around the pressure compensator
valve to the signal pressure passage (Figure 7, Item 6).
The hydraulic oil that flows to the signal pressure passage (Figure 7, Item 6) and the internal passage is signal oil.
The signal oil balances the pressure compensator valve (Figure 7, Item 7) against the hydraulic oil pressure in the
feeder passage (Figure 7, Item 17). This controls the flow across the spool (Figure 7, Item 10).
The signal oil, in the signal pressure passage (Figure 7, Item 6), flows to the pressure compensator valve in each
control valve. The signal oil also flows to the pump control valve on the implement pump. The signal oil helps to
control the output of the implement pump. The implement pump upstrokes and the hydraulic oil pressure in the
passage (Figure 7, Item 15) and the feeder passage (Figure 7, Item 17) increases. When the pressure in the feeder
passage rises above circuit pressure, it unseats the check valves (Figure 7, Items 5 and 8) and oil flows to the
bridge passages (Figure 7, Items 14 and 18). In the bridge passage, the spool (Figure 7, Item 10) blocks the flow of
the oil. However, in the bridge passage, hydraulic oil flows around the spool, into the passage (Figure 7, Item 13),
and then through the port (Figure 7, Item 9), where it flows to the head end of one angle cylinder and the rod end of
the other angle cylinder. From there, hydraulic oil returns to the valve through the port (Figure 7, Item 4) and flows
into the passage (Figure 7, Item 3), around the spool (Figure 7, Item 10), into the passage (Figure 7, Item 1), and
then into the tank.
When the operator stops rolling the roller switch, the flow of pilot oil to the valve is blocked and the pilot oil in the
passage (Figure 7, Item 12) drains to the tank. The loss of pilot oil enables the spring (Figure 7, Item 11) to move
the spool (Figure 7, Item 10) to the HOLD position. Check valves (Figure 7, Items 5 and 8) close and the spool and
the check valves block the hydraulic oil in the hydraulic lines.
The blade angle circuit also has two relief valves (Figure 7, Item 2), which absorb shocks and make sure that the
pressure in the angle cylinders does not exceed a preset limit.
0011-10
