CYLINDER AS 1934079 - Caterpillar

5/2 Solenoid Valve
The 5/2 solenoid valve works in two cycles: A and B. Each cycle consists of a pumping, holding, and releasing stage. In each cycle, grease is pumped and release within the same line.The solenoid valve has two positions: de-energized (OFF) and energized (ON). Lubrication cycles occur alternatively between Line A and B by energizing and de-energizing the solenoid valve alternatively and each has four states:
Pumping – 5/2 valve is de-energized and pressure in line A increases
Retaining – pump stops, 5/2 valve remains de-energized and pressure in line A retained
Decreasing - pump stops, 5/2 valve is energized and pressure in line A decreases
Pause - pump stops, 5/2 valve is de-energized and the entire system is at restCycle A (Pumping)
Illustration 2 g06191344The 5/2 solenoid valve is de-energized. The pump supplies grease through center passage through line (1). Return A (2) is blocked by valve spool and system is pressurized to compress against the spring (3) of pressure switch.Cycle A (Retaining)
Illustration 3 g06191347The 5/2 solenoid valve remains de-energized and pumping stops. The pressure switch is closed but return line A (2) remains blocked holding grease pressure in the system.Cycle A (Decreasing)
Illustration 4 g06191361The 5/2 solenoid valve is energized. The 5/2 solenoid valve spool is shifted Left to release grease from supply line (1). The grease returns through the Return A (2) back to reservoir. System pressure is decreasing.Cycle A (Pause)
Illustration 5 g06224220The 5/2 solenoid valve is de-energized. The system pressure is already decreased, 5/2 solenoid valve spool is stationary, and the entire system is at rest.Cycle B (Pumping)
Illustration 6 g06191368The 5/2 solenoid valve is de-energized. The pump supplies grease through center passage through line B (1). Return B (4) is blocked by valve spool and system is pressurized to compress against the spring (3) of pressure switch.
Illustration 7 g06225318The 5/2 solenoid valve remains de-energized and pumping stops. The pressure switch is closed but return line B (4) remains blocked holding grease pressure in the system.
Illustration 8 g06191371The 5/2 solenoid valve spool is shifted RIGHT to release grease from supply line (1). The grease returns through the Return B (4) back to reservoir.
Illustration 9 g06224220The 5/2 solenoid valve is de-energized. The system pressure is already decreased, 5/2 solenoid valve spool is stationary, and the entire system is at rest.
Illustration 10 g06191427The 177-3520 Valve pressure switch works similarly in the 3 stages of each cycle. Cycle A grease is pumped into 177-3520 Valve from A and released back to A. Cycle B works the same as cycle A.Minimum Level Switch for the Grease
Minimum level switch (6) maintains the level of the grease in the grease reservoir. When the grease reaches the minimum level, the level switch will send a signal to the control unit. At the beginning of each following lubrication cycle, the signal lamp will flash to alert the operator that the grease reservoir must be refilled.Relief Valve
Relief valve (10) is mounted in the grease line between the pump and the diverter valves. The relief valve will redirect the grease to the grease reservoir when the grease