TM 5-2410-240-23-1
0011
IMPLEMENT HYDRAULIC SYSTEM CONTINUED
2. Low Pressure Standby
When the implement pump (Figure 4, Item 1) produces flow, system pressure begins to increase because the
closed center implement control valves block oil flow from the pump outlet (Figure 4, Item 4). The supply pressure
from the pump outlet is felt at the bottom end of the flow compensator (margin) spool (Figure 4, Item 7). The supply
pressure is greater than the load sensing (signal) oil pressure (Figure 4, Item 6), the boost pressure, and the
margin spring pressure (Figure 4, Item 5) combined. The flow compensator (margin) spool then moves upward
against the margin spring, which permits system oil to flow to the actuator piston (Figure 4, Item 3).
When the pressure on the actuator piston (Figure 4, Item 3) increases, the force of the bias spring (Figure 4,
Item 2) is overcome and the swashplate (Figure 4, Item 8) moves to a slight angle. The implement pump (Figure 4,
Item 1) produces enough flow in order to compensate for normal system leakage when the swashplate is at a slight
angle. In addition, the implement pump has sufficient pressure in order to provide instantaneous response when
the operator activates an implement.
Pressure at the pump outlet (Figure 4, Item 4) is called low pressure standby. The low pressure standby is higher
than the margin pressure due to the additional load sense boost pressure. The higher pressure is necessary to
improve implement response time. The supply pressure from the pump outlet raises the flow compensator (margin)
spool (Figure 4, Item 7) higher when the implement pump (Figure 4, Item 1) is at low pressure standby. This will
further compress the margin spring (Figure 4, Item 5). In turn, larger amounts of supply oil will flow from the pump
outlet to the actuator piston (Figure 4, Item 3). This will slightly destroke the implement pump.
N OT E
The low pressure standby is adjustable by changing the setting of the margin spring
(Figure 4, Item 5).
0011-6