0435546 JOHNSON PISTON & PIN ASSY., Std.

Travel Speed
The "TRAVEL SPEED" key is used to select one of the following two travel speeds:
HIGH
LOWWhen the "HIGH" travel speed is selected, the controller will activate the travel speed solenoid. This activation will cause the travel speed to increase according to the travel load. Selecting the "LOW" travel speed will deactivate the travel speed solenoid. This action will cause the travel speed to decrease. For more information, see the following topics:
Hydraulic System Systems Operation, "Trenching Operation"
Hydraulic System Systems Operation, "Leveling Operation"
Hydraulic System Systems Operation, "Pilot Circuit"
Hydraulic System Systems Operation, "Travel Control"Backup System
Illustration 1 g00662823
(1) Backup switch (2) Speed change switchThe controller has a backup system in order to prevent uncontrolled operation of the pump and/or engine. When the backup switch (1) is placed in the manual position, the following conditions result:
The proportional reducing valve is disconnected from the drive circuit of the proportional reducing valve. Then, the reducing valve is driven by a constant current that is adjusted by the backup resistor. The power shift pressure is kept constant and pump output is in the standard mode.
The monitor does not display any information. The controller and the monitor are not receiving power.
The engine speed can be controlled by the speed change switch (2). The engine speed will be increased, if the speed change switch is placed in the rabbit position. The engine speed will be decreased, if the switch is placed in the tortoise position. The switch returns to the neutral position when the switch is released.
The swing parking brake is released. However, the parking brake is engaged when the primary pilot pressure is reduced to near zero by placing the hydraulic activation control lever to the lock position or by stopping the engine.Prevention Of High Speed Start Of The Engine
In a conventional excavator, the engine will start in high speed with the engine speed dial in a high position (10) after the engine has been stopped. The following information will describe the actions that are designed in order to prevent a high speed start.When the engine key start switch is placed in the OFF position, the governor actuator will stop. The governor lever is maintained in the identical position. The engine will restart at a RPM of 1300 or 1000 rpm, if the engine is stopped and the second stage of the AEC is operating. The engine will also restart at a RPM of 1300 or 1000 rpm, if the engine is stopped and the low idle switch is in the ON position. This function is designed to keep the governor actuator in position when the operation is terminated. Any of the following conditions can cause the termination:
A control lever or a pedal is operated. A implement/swing switch, travel switch or boom raise pressure switch is turned to the ON position.
The engine speed dial is operated.
The AEC switch is operated.
The power mode switch is operated.Then, the engine speed will correspond to the position of the engine speed dial. Operation of the low idle switch will also terminate this function. However, the engine speed is 1000 rpm even if the position of the engine speed dial is greater than 2.The engine will restart at a high speed, if the governor actuator is held in a high speed position before stopping the engine. The speed of the engine will decrease to 1300 rpm. The speed is automatically decreased 3 seconds after the starting of the engine. The second stage of the AEC must be in the ON position.Preventing Over Speed During Low Engine Oil Pressure
This function is designed to prevent the engine from starting at a high speed during a condition of low oil pressure. After the engine oil filter is replaced, a long time may be required before the engine oil pressure will reach the specified level. The turbocharger may be damaged, if the engine runs at the speed dial position of 10. The following information describes this function.The engine speed will be limited to the position of 5, if the engine oil pressure switch is open. The engine speed will also be limited to the position of 5, if the governor actuator was held in the high speed position before the stopping of the engine. The engine will start at the speed of the 5 position.This function is designed to keep the governor actuator in position when the operation is terminated. Any of the following conditions can cause the termination:
A control lever or a pedal is operated. A implement/swing switch, travel switch or boom raise pressure switch is turned to the ON position.
The engine speed dial is operated.
The AEC switch is operated.
The power mode switch is operated.Then, the engine speed will correspond to the position of the engine speed dial. Operation of the low idle switch will also terminate this function. However, the engine speed is 1000 rpm even if the position of the engine speed dial is greater than 2.The engine will restart at a high speed, if the governor actuator is held in a high speed position before stopping the engine. The speed of the engine will decrease to 1300 rpm. The speed is automatically decreased 3 seconds after the starting of the engine. The second stage of the AEC must be in the ON position.Swing Lock System
The swing parking brake is released immediately after any control lever of the boom, stick, bucket, swing or attachment is operated. The swing parking brake is engaged 6.5 seconds after all the control levers return to the neutral position. The swing parking brake is not released while the hydraulic activation control lever is placed to the locked position. The swing parking brake is released by turning the fine swing switch to the ON position, if the fine swing attachment is installed.