LEVER 3T1748 - Caterpillar

Illustration 1 g01324584
Block Diagram for the Transmission System
(1) Charge pump
(2) Auto switch
(3) Shift lever
(4) Inching pedal
(5) Filter (OEM)
(6) Transmission ECM
(7) Relief valve
(8) Oil cooler
(9) Transmission
(10) Modulating valves (transmission)
(11) Sump The operator can initiate a hydraulic function by using one of the following controls:
Auto switch (2)
Shift lever (3)
Inching pedal (4)The controls will send a signal to the transmission electronic control module (ECM) (6). The transmission ECM will then process these signals.The transmission ECM will energize modulating valve (transmission) (10).Sump (11) is located in the transmission case. Sump (11) supplies charge pump (1) with oil. The oil goes through filter (5). The oil is then delivered to relief valve (7) (charge pressure). The relief valve controls the oil pressure to 2100 kPa (305 psi). All excess oil is routed through oil cooler (8). The oil then goes to the transmission lubrication circuit.Transmission Electrical Control System
Illustration 2 g01324643
Electrical Block Diagram for the Transmission System
(2) Auto shift switch
(6) Transmission ECM
(12) Dash panel display
(13) CAT data link
(14) Service connector
(15) Charge pressure sensor
(16) Hydraulic oil temperature sensor
(17) 2 output speed sensors
(18) Input speed sensor
(19) Inching pedal position sensor
(20) Inching pedal switch
(21) Shift lever position sensor
(22) Modulating valve (clutch H)
(23) Modulating valve (clutch J)
(24) Modulating valve (clutch C)
(25) Modulating valve (clutch B)
(26) Modulating valve (clutch D)
(27) Modulating valve (clutch G)
(28) Modulating valve (clutch E)
(29) Modulating valve (clutch F)
(30) Modulating valve (clutch A)
(31) CAN data link
(32) Service connector The electrical system for the transmission consists of the following components:
Auto shift switch (2)
Transmission ECM (6)
Dash panel cluster (12)
CAT data link (13)
Service connector (14)
Charge pressure sensor (15)
Hydraulic oil temperature sensor (16)
2 output speed sensors (17)
Input speed sensor (18)
Inching pedal position sensor (19)
Inching pedal switch (20)
Shift lever position sensor (21)
Modulating valve (transmission clutches No. 1 - No. 9) (22 - 30)
CAN data link (31)
Service connector (32) Transmission ECM (6) controls solenoid valve (22) through solenoid valve (30) for the transmission.CAT data link (13) is a serial communication bus that is used in order to communicate with the following component:
Caterpillar electronic technician (ET)CAN data link (31) is a serial communication bus that is used in order to communicate with the following components:
Engine ECM
Transmission ECM
Dash panel cluster
Other OEM electronic control modulesShift lever position sensor (21) sends a PWM signal to transmission ECM (6). Transmission ECM (6) processes the signal in order to determine the position of lever (21).Speed sensors (17) and (18), temperature sensor (16), and pressure sensor (15) send signals to transmission ECM (6). The transmission ECM uses the signals in order to monitor the conditions of the transmission.Transmission Hydraulic System
Illustration 3 g01324659
Block Diagram for the Transmission Hydraulic System
(1) Charge pump
(5) Filter
(7) Main relief valve
(8) Oil cooler
(9) Transmission
(10) Modulating valves
(11) Sump
(33) Suction screen
(34) Cooler bypass valve
(35) Lube relief valve Oil from sump (11) is drawn through suction screen (33) by the charge pump (1). Suction screen (33) is rated at 200 micron. Hydraulic oil filter (5) filters the oil from charge pump (1).Filtered oil is supplied to following valves:
Relief valve (7)
Modulating valves (transmission) (10)When the modulating valves are energized, oil flows to the