LINES GP-TILT CYLINDER 3844185 - Caterpillar

Introduction
The boom cylinder dampening system is designed to increase the stability of the excavator during a BOOM RAISE operation. This action is achieved by decreasing the speed of the boom as the boom cylinders near full extension. The boom dampening system uses a boom up limit valve. The boom up limit valve is an electronic reverse proportional reducing valve.
Illustration 1 g01892878
Cab platform (bottom view)
(1) Boom up-limit valve
(2) Pressure tap for solenoid valve
(3) Pilot line
(4) Pilot line
(5) Drain line This system utilizes boom up-limit valve (1) to control pilot pressure to the boom control valves. Boom reduction valve (1) is a pressure reducing valve. In the system, boom up-limit valve (1) is located between the joystick and the boom control valves. This valve is mounted on the cab platform.
Illustration 2 g01892877
Boom angle sensor
(6) Boom foot
(7) Lever
(8) Potentiometer The boom angle sensor within the boom cylinder dampening system communicates the angle of the boom to the machine ECM. The boom angle sensor is mounted on boom foot (6). Lever (7) controls the position of potentiometer (8) within the angle sensor as the boom raises. This sensor generates a signal that is sent to the machine ECM. The machine ECM uses this information to control boom up-limit valve (1) on the pilot circuit.
Illustration 3 g01892881
Pilot oil pressure versus boom angle
(9) Pilot oil pressure
(10) Pressure reduction from proportional reducing valve
(11) End of cylinder stroke for BOOM RAISE The machine ECM sends a PWM signal to boom up-limit valve (1). When the PWM signal is reduced, the boom up-limit valve (1) reduces pilot oil pressure (9) to the boom control valves in order to slow the boom at the end of the stroke for the BOOM RAISE (11).Boom Raise Operation (Normal)
Illustration 4 g03414159
Normal operation of BOOM RAISE (full pilot oil flow to boom control valves)
(1) Boom up limit valve
(3) Pilot line (pilot oil from joystick)
(4) Pilot line (pilot oil to boom control valves)
(5) Drain line
(12) Boom cylinders
(13) Boom I control valve
(14)