EDGE AS 2443889 - Caterpillar

Float Position
When the lift control lever is moved to FLOAT position, there is a detent that holds the lever in FLOAT. The movement in the lift and tilt pilot valve is the same as in LOWER position, except lower stem (12) is pushed down farther. Vent passage (16) is now open to tank passage (17) through groove (23). The oil in vent passage (16) holds the make-up valve, for the rod end of the lift cylinders, closed in LOWER position. In FLOAT position, the make-up valve opens and lets oil from the large section of the main pump go directly to drain (tank). There is no pressure oil to the rod end of the lift cylinders, so the weight of the bucket and lift arms causes the bucket to lower.The flow of oil from pump passage (20) through holes (14) and out passage (18) is the same as in LOWER position. The lift valve spool is in the same position in LOWER and FLOAT.
LIFT AND TILT PILOT VALVE (Lower Stem in FLOAT Position)
12. Lower stem. 14. Holes. 16. Vent passage. 17. Tank passage. 18. Passage to lift valve spool. 20. Pump (supply) passage. 23. Groove.Lower Position With Engine Off
When the engine is off, the lift cylinders can still be operated if there is pressure in the lift cylinder lines (head or rod end). When the front of the machine is lifted off the ground, there is pressure on the rod end of the lift cylinders. When the bucket is off the ground, there is pressure on the head end of the lift cylinders. When the engine is off in either of these conditions, the oil comes from the higher of the two pressures (head or rod end) into vent passage (16) of the lift and tilt pilot valve. When the lift control lever is moved to LOWER position and on to FLOAT position, either the bucket or the front of the machine will lower to the ground.The movement of lower stem (12) is the same as in FLOAT position when the engine is running. Vent passage (16) is opened to tank passage (17) which releases the pressure of oil in the lift cylinders. If the bucket is off the ground, the weight of the bucket and lift arms causes the bucket to lower. If the front of the machine is off the ground, the weight of the machine causes the front of the machine to lower.Hold Position Of Tilt Operation
When the tilt control lever is in HOLD position, plungers (26) and (27) are in the same position (as shown). The plungers do not push up against actuator (24) in the hold position. Pressure oil from the pilot pump goes through pump passage (20) and is stopped by the position of stems (34) and (35). Holes (36) and (37) are open to tank passage (11).Spring (33) pushes up on retainer (28) and plunger (26). Spring (31) holds tilt back stem (35) down against retainer (28). Spring (32) pushes up