 | |
| Illustration 1 | g00348786 |
Location of Measuring Arm (1) Measuring wheel. (2) Length sensor. (3) Measuring arm cylinder. | |
Hydraulic oil flows to measuring arm cylinder (2) from the main control valve. The cylinder controls the movement of measuring wheel (1) into the tree.
The measuring arm moves into the log when the feed roller arms close. The measuring arm moves away from the log when the feed roller arms open.
The length sensor (2) measures the length of the log. As measuring wheel (1) rotates, length sensor (2) sends an electrical signal to the computer aided bucking system. The computer aided bucking system uses the diameter and length to determine the most preferable length for the log.
| Electrical Actuation of Valve Sections | |||
| Voltage | 6 V to 10.5 V | 12 ± 1.5 V (1) | 13.5 V to 18 V |
| Function | Position | ||
| Measuring Arm (2) | IN | NEUTRAL | N/A |
| ( 1 ) | The deadband is ± 1.5 volts. |
| ( 2 ) | The measuring arm is controlled by the same spool as the feed roller arms. |
NEUTRAL Position
 | |
| Illustration 2 | g00758485 |
Schematic of the Control System (3) Measuring arm cylinder. (4) Main control valve. (5) Line relief valves. (6) Proportional solenoid. (7) Valve spool. (8) Resolver. (9) Signal limiter valve. (10) Signal limiter valve. (11) Flow compensator valve. (12) Pressure reducing valve. (13) Resolver. (AA) Pressure tap. (C) Pilot pressure line. (D) Signal line. (E) Pressure line. (F) Return line. (G) Line to feed roller arm cylinders (OPEN). (H) Line to color marking system. | |
When the feed roller arms are not being used, proportional solenoid (6) receives a 12 volt pulse width modulated signal from the computer aided bucking system. Valve spool (7) remains in the NEUTRAL position.
When valve spool (7) is in the NEUTRAL position, there is no signal pressure from this section of the main control valve.
Line relief valves (5) protect the feed roller arm cylinders and hydraulic oil lines from damage when valve spool (7) is in the NEUTRAL position. When an external load acts on the feed roller arms, the oil pressure in the circuit increases. When the pressure in the circuit exceeds the relief valve pressure setting, the line relief valve opens. The oil in the circuit flows to the hydraulic oil tank on the machine through return line (F) .
IN Position
When proportional solenoid (6) receives a 6 to 10.5 volt signal, the feed roller arms open and the measuring arm retracts. Solenoid (6) causes valve spool (7) to move to the DOWN position.
As the feed roller arms open, pressurized oil flows through port "B" to the rod end of the measuring arm cylinder. The oil pressure to the rod end is greater than the oil pressure to the head end which causes the measuring arm to retract.
Oil from the head end of the measuring arm cylinder returns to pressure reducing valve (12). Then, the oil returns to the hydraulic oil tank through return line (F) .
OUT Position
When proportional solenoid (6) receives a 13.5 to 18 volt signal, the feed roller arms close and the measuring arm extends. Solenoid (6) causes valve spool (7) to move to the UP position.
Pressure oil flows through pressure reducing valve (12) to the head end of measuring arm cylinder (3).
Oil from the rod end of the measuring arm cylinders returns to the main control valve. From the main control valve, the oil returns to the hydraulic oil tank through return line (F) .
Pressure reducing valve (12) controls the pressure in the head end of the measuring arm cylinder. Pressure reducing valve (12) can be adjusted. As the oil pressure in the head end of the measuring arm cylinder increases, the measuring wheel presses further into the tree. This oil pressure in the head end of the cylinder is measured at pressure tap (AA) .
Valve spool (7) remains in the UP position while the tree is processed. With the valve spool in the UP position, the measuring arm keeps pressure on the tree.