GEAR 4D4004 - Caterpillar

Illustration 1 g03078126
General InformationThe front drum and the rear drum on the machines are hydrostatically driven. The drive system consists of the following components:
A variable-displacement piston-type tandem pump group
Four radial piston motors
A spring applied, hydraulically released brake on each motorThe charge pump supplies charge oil to the propel system.
Illustration 2 g03078128
Propel Control System (1) Engine ECM (2) Left Front Speed Sensor (3) Right Rear Speed Sensor (4) Split Drum Module (5) Machine ECM (6) Propel forward solenoid "2" (7) Propel reverse solenoid "2" (8) Front Backup Alarm (9) 360-reverse relay (10) Rear backup Alarm (11) Keypad (12) Parking Brake Switch (13) Propel lever (14) Seat Position Switch "1" (15) Seat Position Switch "2" (16) Diagnostic connector (17) Parking brake solenoid (18) Propel reverse solenoid "1" (19) Propel forward solenoid "1" (20) Right front speed sensor (21) Display (22) Left rear speed sensorNote: The blue lines in the above illustration indicate an input signal. The red lines indicate an output signal. The red and blue lines indicate two-way communications.Machine ECM (5) monitors input signals from the following components in order to control the propel system:
Engine ECM (1)
Keypad (11)
Parking brake switch (12)
Propel lever (13)
Right front speed sensor (20)
Seat position switch "1" (14)
Seat position switch "2" (15) Display (21) monitors input signals from left rear drum speed sensor (22). This information is relayed to machine ECM (5) via CAN lines.Split drum module (4) monitors input signals from left front speed sensor (2) and right rear speed sensor (3). This information is relayed to machine ECM (5) via CAN lines.Machine ECM (5) evaluates the input signals and determines if any output signals should be sent to the propel control solenoids. The machine ECM sends control signals directly to propel forward solenoid "1" (19) and propel reverse solenoid "1" (18). The machine ECM transmits control signals for propel forward solenoid "2" (6) and propel reverse solenoid "2" (7) via CAN lines to split drum module (4). The split drum module forwards these signals to the corresponding control solenoids.Machine ECM (5) monitors two seat position switches (14) and (15) in order to determine which direction the operator station is facing. This information is relayed to engine ECM (1) via CAN lines. The engine ECM transmits a control signal to back up alarm relay (9) based on the direction of the operator station. If propel lever (13) is operating in the reverse range, the machine ECM energizes appropriate back-up alarm (8) or (10) via the back-up alarm relay (9) .Machine ECM (5) uses display (21) in order to provide information to the operator about the propel system during operation.The propel system section of this presentation is divided into segments. The first segments show the location of all electrical and hydraulic components on the machine which are part of the propel system. A brief discussion of each component is provided in these segments. The last two sections explain the operation of the electrical and hydraulic systems. Schematics are used in this segment to trace current through the electrical