BREATHER AS 2028687 - Caterpillar

Boom Down Control Pressure Sensor
Pressure sensor for boom down control measures the pilot oil pressure during a boom DOWN function. The pressure sensor for boom down control sends a voltage signal to the machine ECM. The machine ECM uses the pressure information to reduce engine speed and pump flow during a boom down function. Also, whenever the pilot pressure exceeds 500 kPa (73 psi) the machine ECM energizes the swing brake solenoid valve. This action releases the swing parking brake.Swing Control Pressure Sensor
Pressure sensor for swing control measures the pilot oil pressure during a swing function. The pressure sensor sends a voltage signal to the machine ECM. The machine ECM uses the pressure information to control the swing priority solenoid valve. Whenever the pilot pressure exceeds 2750 kPa (400 psi) the machine ECM de-activates the swing priority solenoid valve to enable swing priority. Whenever the pilot pressure exceeds 500 kPa (73 psi) the machine ECM energizes the swing brake solenoid valve to release the swing parking brake.Pressure sensor for swing control is also used to prevent oil loss over the crossover relief valve at the start of a swing function. The swing operation is detected with the swing pilot pressure sensor. The swing load pressure is detected with the idler pump pressure sensor. The main pump flow is reduced when the idler pump pressure sensor is higher than the crossover relief valve pressure setting determined by the machine ECM. The machine ECM sends a PWM signal to destroke the idler pump.The machine ECM also reduces the idler pump flow during inching operation. Swing inching is detected by the pressure sensor for swing control. This function is only activated when no other implements are being operated.The left travel pressure sensor and right travel pressure sensor detects travel operation. The travel pressure sensors send an input signal to the machine ECM. The machine ECM uses the sensor information to control the engine speed and pump control.The implement pressure sensor sends an input signal to the machine ECM. When the joysticks are moved from the NEUTRAL position for a boom UP, stick IN, stick OUT, bucket IN, or a bucket OUT operation, pilot oil is directed to the implement pressure sensor. The implement pressure sensor sends an electrical signal to the machine ECM. The sensor information is used to control engine speed and pump control. Also, an electrical signal from the machine ECM energizes the swing brake solenoid valve to release the swing parking brake.Note: The implement pressure sensor does not detect a boom lower or a swing operation.Outputs
The ECM responds to inputs by sending electrical signals to the outputs. The outputs can create an action or the outputs can provide information to the operator or service technician. The outputs of the ECMs are listed in tables 1, 2, and 3.On/Off Solenoids
Illustration 6 g01158530The values in Table 5 are for bench testing only. Values may not represent parameters for machine systems specifications.
Table 5
Rated Voltage 24 VDC
Coil Resistance 32.0 3.2Ω (T=20° C)