BRACKET 3779408 - Caterpillar

LOW SPEED
Illustration 8 g06315078
Left travel motor (LOW SPEED)
(1) Left travel motor
(2) Swashplate
(3) Motor rotary group
(4) Swashplate control piston
(6) Passage
(7) Displacement change valve
(8) Passage
(9) Counterbalance valve
(12) Passage
(32) Pilot line
(46) Pressure sensor (main pump)
(48) Travel speed solenoid valve
(50) Main pump
(57) Travel speed control switch
(58) Left travel lever/pedal
(B) Indicator for HIGH SPEED
(C) Indicator for LOW SPEED
(D) Machine ECM
(E) Main control valveWhen travel speed control switch (57) is set at the LOW SPEED position (C), an electrical signal is sent to machine ECM (D). Machine ECM (D) does not energize travel speed solenoid valve (48) and pilot system oil pressure does not flow through pilot line (32) to displacement change valve (7). The spool in displacement change valve (7) does not shift. A portion of the oil flow from pump (50) in passage (6) flows through passage (8) and displacement change valve (7) to swashplate control piston (4). As a result, swashplate control piston (4) moves swashplate (2) to the maximum displacement position. At the same time, the oil that acts on swashplate control piston (4) flows into the case drain of travel motor (1). One rotation of motor rotary group (3) displaces a larger amount of oil flow. The rotational speed of left travel motor (1) decreases. The left track moves slowly and better traction is achieved.The return oil from motor rotary group (3) flows through passage (12), counterbalance valve (9), line (27), and swivel (29). The return oil then flows through line (37), left travel control valve (45), return passage (44), and return line (49) to the hydraulic tank.Right travel motor (15) receives the oil delivery from pump (50). Right travel motor (15) functions in the same manner as left travel motor (1) in the LOW SPEED position.HIGH SPEED
Illustration 9 g03697968
Travel speed solenoid location
(48) Travel speed solenoid valve
Illustration 10 g06315080
Left travel motor (HIGH SPEED)
(1) Left travel motor
(2) Swashplate
(3) Motor rotary group
(4) Swashplate control piston
(6) Passage
(7) Displacement change valve
(8) Passage
(9) Counterbalance valve
(12) Passage
(32) Pilot line
(46) Pressure sensor (main pump)
(48) Travel speed solenoid valve
(50) Main pump
(57) Travel speed control switch
(58) Left travel lever/pedal
(B) Indicator for HIGH SPEED
(C) Indicator for LOW SPEED
(D) Machine ECM
(E) Main control valveWhen travel speed control switch (57) is set at the HIGH SPEED position, an electrical signal is sent to machine ECM (D). Pressure sensor (46) also send an electrical signal to machine ECM (D). If the travel load is light and when the pump delivery pressure is below a certain pressure, machine ECM (D) energizes travel speed solenoid valve (48). Pilot system oil pressure flows through travel speed solenoid valve (48) and line (32) to displacement change valve (7). The spool in displacement change valve (7) shifts. A portion of the oil delivery from main pump (50) flows through displacement change valve (7) to swashplate control piston (4). Swashplate control piston (4) moves swashplate (2) to the minimum displacement position. At the same time, the oil that acts on swashplate control piston (4) flows into the case drain of travel motor (1). One rotation of motor rotary group (3) displaces