320C Excavator Hydraulic System – Electronic Control System



Illustration 1 g00902442

(1) Engine and pump controller

(2) Fuse panel

(3) Engine

(4) Governor lever

(5) Main pumps

(6) Battery

(7) Engine start switch

(8) Engine speed sensor

(9) Backup switch

(10) Governor actuator

(11) Feedback sensor

(12) Monitor

(13) Action alarm

(14) Engine speed dial

(15) Switch panel

(16) Engine coolant temperature sensor

(17) Hydraulic oil temperature sensor

(18) Fuel level sensor

(19) Alternator

(20) Engine oil pressure sensor

(21) Manual low idle switch

(22) Engine oil level switch

(23) Hydraulic oil level switch

(24) Water separator

(25) Implement/swing pressure switch

(26) Right travel pressure switch

(27) Left travel pressure switch

(28) Straight travel pressure switch

(29) Right pump pressure sensor

(30) Left pump pressure sensor

(31) Power shift solenoid

(32) Straight travel speed solenoid valve

(33) Travel speed solenoid valve

(34) Swing parking brake solenoid valve

(35) Travel alarm

(36) Air heater indicator

(37) Restricted air filter switch

(38) Restricted hydraulic return filter indicator

(39) Engine coolant level switch

(40) Pressure switch (attachment pump)

(41) Attachment pedal pressure switch (1)

(42) Attachment pedal pressure switch (2)

(43) Proportional reducing valve for auxiliary hydraulics



Illustration 2 g00673776

(1) Engine and pump controller



Illustration 3 g00673780

(12) Monitor

The electronic control system consists of monitor (12) in the cab and the engine and pump controller (1) that is located in the compartment behind the cab. The electronic control system controls the engine speed and the pumps through the engine and pump controller.

Engine and pump controller (1) receives input signals from various components on the machine. The engine and pump controller continuously monitors the input signals in order to control the output flow rate of the main pumps, engine speed and various components of the machine hydraulic systems.

The electronic control system has the following three major functions.

  • The electronic control system controls the output flow rate of the main pumps. The engine and pump controller sends an electrical signal to the power shift solenoid that is based on engine speed and the position of the engine speed dial. This allows the main pumps to supply the optimum output that matches the hydraulic load to the machine and the engine speed. When a large load is placed on the machine, the system allows the pumps to destroke. The system utilizes the available maximum engine horsepower.

  • The electronic control system controls the engine speed. This is called Automatic Engine Speed Control (AEC). When there is a very small load condition or no load condition, the system automatically decreases the engine speed. The AEC system is designed to reduce fuel consumption and noise.

  • The electronic control system controls various components of the machine hydraulic systems. The engine and pump controller sends output signals to the swing parking brake solenoid valve, the travel speed solenoid valve and the straight travel solenoid.

Note: If a problem occurs in the electronic control system, temporary operation of the machine is possible by use of the backup switches that are located in the cab. For more information concerning the backup system, refer to Operation and Maintenance Manual, “Backup Controls”.

Reference: For more information concerning the operation of the electronic control system, refer to Systems Operation/Testing and Adjusting, “Engine and Pump Electronic Control System”.