General Information
 | |
| Illustration 1 | g00635727 |
Schematic of the Control Valve for the Hydraulic Retrieval Device (One Bank) (1) Decking blade cylinders (2) Hydraulic Retrieval Device (3) Solenoid valve for Hydraulic Retrieval Device (4) Arch cylinders (5) Steering, decking blade, and brake valve (6) Control valve for Hydraulic Retrieval Device (one bank) (7) Grapple control valves (three, four, or six bank) (A) Reel out port (B) Reel in port (C) Pilot drain line (D) Pilot supply line (E) Pilot supply line (engine stopped) (F) Pilot supply line to grapple control valve (G) Pilot drain line to grapple control valve (H) Return line from main valve | |
The Hydraulic Retrieval Device (HRD) is an attachment on the 515 Wheel Skidder and 525 Wheel Skidder. The HRD is used only for retrieving machines that are struck. The control valve of the HRD can be mounted as a one bank control valve or in a six bank control valve for the grapple.
Note: The six bank grapple control valve is only used on the 525 Wheel Skidder.
The Hydraulic Retrieval Device has two control switches, solenoid valve (3), control valve (6), and a hydraulic motor.
The HRD is controlled by two switches that are located on the right side console near the grapple control lever. The front switch controls the solenoid valve for the freespool function. The solenoid valve is located on the right side of the machine below the HRD. The front switch is a two-position switch that controls the freespool function. While the switch is in the OFF position, the drum of the HRD is engaged. The drum will not unwind freely. When the switch is moved to the ON position, the drum of the HRD is disengaged. The drum will unwind freely. The back switch enables the control valve for the HRD. The back switch is a three-position switch that controls the direction of the HRD. The three positions are REEL IN, HOLD, or REEL OUT.
Hydraulic Retrieval Device Valve in the Hold Position
 | |
| Illustration 2 | g00635976 |
Hydraulic Retrieval Device Valve (HOLD Position) (8) Pilot oil chamber (9) Spring (10) Passage to tank (11) Signal passage (12) Port (B) to hydraulic motor (reel in) (13) Control spool (14) Port (A) to hydraulic motor (reel out) (15) Signal passage (16) Passage to tank (17) Spring (18) Pilot oil chamber (19) Solenoid valve (20) Port (21) Spring (22) Spring cavity (23) Passage (24) Passage (25) Pump passage (26) Spool (27) Chamber (28) Solenoid valve | |
When the HRD control valve is used as a separate attachment on either machine, the control valve section will be located between the decking blade valve section and the arch valve section. Pump oil flows from the decking blade valve section to the HRD valve through passage (25). The location of passage (25) in the valve is common in all valve sections. The passage has no outlet.
When the operator places the control switch in the HOLD position, solenoids (19) and (28) block pilot oil from flowing into both chambers (8) or (18). Centering springs (9) and (17) keep control spool (13) in the HOLD position.
Oil flows into passage (24) through openings in spool (26). The oil then flows into chamber (27) .
Oil pressure in chamber (27) increases. This acts against spool (26) until the oil pressure overcomes the force of spring (21). This causes spool (26) to move to the left. As spool (26) moves left, oil flows from passage (25) into passage (23). The oil in passage (23) is blocked by spool (13) .
As spool (26) moves left, slots in the spool begin to close. When the slots close, oil flow from passage (25) to passage (23) is restricted. Oil then flows from signal passage (11) into spring cavity (22) through port (20) .
Oil is now metered through the slots in spool (26) in order to maintain pressure in chamber (27) and passage (25) above the pressure in signal cavity (11). This pressure is lower than pump pressure in passage (25) .
In the HOLD position, spool (13) blocks the oil in passage (23) from flowing into either ports (12) or (14). The oil in the hydraulic motor and oil lines are also blocked at ports (12) and (14) .
Since no oil flows to the hydraulic motor, oil in passages (10), (11), (15), (16), and (20) will return to the hydraulic oil tank.
Hydraulic Retrieval Device Valve in the REEL IN Position
| | |
| Illustration 3 | g00635976 |
Hydraulic Retrieval Device Valve (REEL IN Position) (8) Pilot oil chamber (9) Spring (10) Passage to tank (11) Signal passage (12) Port (B) to hydraulic motor (reel in) (13) Control spool (14) Port (A) to hydraulic motor (reel out) (15) Signal passage (16) Passage to tank (17) Spring (18) Pilot oil chamber (19) Solenoid valve (20) Port (21) Spring (22) Spring cavity (23) Passage (24) Passage (25) Pump passage (26) Spool (27) Chamber (28) Solenoid valve | |
When the operator places the control switch in the REEL IN position, solenoid valve (19) energizes. Solenoid valve (19) shifts and routes pilot oil into chamber (8) .
The pilot oil acts against spool (13) which overcomes the force of spring (17). This causes spool (13) to move to the right. This blocks passage (10) which prevents the flow of oil back to the hydraulic oil tank. Pump oil flows from the decking blade valve into the HRD valve through passage (25). Oil flows into passage (24) through opening in spool (26). The oil then flows into chamber (27) .
Pressure in chamber (27) increases. The pressure acts against spool (26) until this pressure overcomes the force of spring (21). This causes spool (26) to move left. As spool (26) moves left, oil flows from passage (25), and into passage (23) .
As spool (13) starts to move to the right, oil flows past the spool, into signal passage (11), and back to the pump control. This causes the pump to upstroke.
When spool (13) moves far enough to the right, the oil flows from passage (23), past the spool, and into port (12). Most of the oil then flows to the hydraulic motor in the HRD. The HRD will rotate in the REEL IN direction. In the REEL IN position, the reel will rotate in a counterclockwise direction.
Return oil from the hydraulic motor in the HRD flows to port (14). From port (14), the oil flows past spool (13), and through passages (15) and (16). The oil then flows from passage (16) back to the hydraulic oil tank.
In the REEL IN position, pressure in port (20) is equal to the pressure in passage (11). The rest of the oil in port (12) flows through passage (11) to the secondary resolver in the next implement valve closer to the pump.
When the pressure of the resolver oil from the next implement is higher than the pressure of the resolver oil from any other circuit the resolver will shift. When the resolver valve shifts, the valve allows that implement's oil to flow to the pump compensator valve. This oil pressure is used in order to adjust the pump output that is required by the load.
When the operator releases the control switch, the flow of pilot oil is blocked. Spring (17) at the right side of spool (13) returns the spool to the HOLD position. This blocks oil flow to the hydraulic motor. The motor will now remain in the HOLD position until the operator moves the control switch.
Hydraulic Retrieval Device Valve in the REEL OUT Position
| | |
| Illustration 4 | g00635976 |
Hydraulic Retrieval Device Valve (REEL OUT Position) (8) Pilot oil chamber (9) Spring (10) Passage to tank (11) Signal passage (12) Port (B) to hydraulic motor (reel in) (13) Control spool (14) Port (A) to hydraulic motor (reel out) (15) Signal passage (16) Passage to tank (17) Spring (18) Pilot oil chamber (19) Solenoid valve (20) Port (21) Spring (22) Spring cavity (23) Passage (24) Passage (25) Pump passage (26) Spool (27) Chamber (28) Solenoid valve | |
When the operator places the control switch in the REEL OUT position, solenoid valve (28) energizes. Solenoid valve (28) shifts and routes pilot oil into chamber (18) .
The pilot oil acts against spool (13) which overcomes the force of spring (9). This causes spool (13) to move to the left. This blocks passage (16) which prevents the flow of oil back to the hydraulic oil tank. Pump oil flows from the decking blade valve into the HRD valve through passage (25). Oil flows into passage (24) through opening in spool (26). The oil then flows into chamber (27) .
Pressure in chamber (27) increases. The pressure acts against spool (26) until this pressure overcomes the force of spring (21). This causes spool (26) to move left. As spool (26) moves left, oil flows from passage (25), and into passage (23) .
As spool (13) starts to move to the left, oil flows past the spool, into signal passage (15), and back to the pump control. This causes the pump to upstroke.
When spool (13) moves far enough to the left, the oil flows from passage (23), past the spool, and into port (14). Most of the oil then flows to the hydraulic motor in the HRD. The HRD will rotate in the REEL OUT direction. In the REEL OUT position, the reel will rotate in a clockwise direction.
Return oil from the hydraulic motor in the HRD flows to port (12). From port (12), the oil flows past spool (13), and through passages (10) and (11). The oil then flows from passage (10) back to the hydraulic oil tank.
In the REEL OUT position, pressure in port (20) is equal to the pressure in passage (15). The rest of the oil in port (14) flows through passage (15) to the secondary resolver in the next implement valve closer to the pump.
When the pressure of the resolver oil from the next implement is higher than the pressure of the resolver oil from any other circuit the resolver will shift. When the resolver valve shifts, the valve allows that implement's oil to flow to the pump compensator valve. This oil pressure is used in order to adjust the pump output that is required by the load.
When the operator releases the control switch, the flow of pilot oil is blocked. Spring (9) at the left side of spool (13) returns the spool to the HOLD position. This blocks oil flow to the hydraulic motor. The motor will now remain in the HOLD position until the operator moves the control switch.
Note: For more information on the operation of the hydraulic retrieval device, refer to the Service Manual module Operation and Maintenance Manual, SEBU6471, "515 Wheel Skidder and 525 Wheel Skidder".