PLUNGER-LIMITER 2W4617 - Caterpillar

Operating on Ground Slopes
If the loader is weighing material on a slope, it will change the relationship between cylinder pressure and payload. If the loader is facing up-hill while weighing, the pressure will be higher in the cylinder for the same payload measured on flat ground. If the loader is facing downhill, the cylinder pressure will be lower than the same payload measured on flat ground.Ride Control Activation in the Weigh Range
The payload system accuracy should be within the stated precision with the ride control system on or off. However, if the ride control system activates or de-activates in the weigh range, it can cause a pressure ripple that will skew the average pressure trace and affect the payload reading. This typically does not happen with the default ride control activation speed of 6kph (3.8 mph), however if the operator is traveling faster than normal or if the ride control activation speed is lowered from the default 6kph (3.8 mph), it could cause a payload accuracy complaint. The errors could be intermittent because ride control may not activate in the weigh range on every pass.Sensors to Check and Calibrations to Perform
Lift and Tilt Position Sensors and Calibration
The linkage position sensors are important to identify that the bucket is fully racked when going through the weigh range as well as to identify the weigh range during the lift. Sensor quality issues can cause signals to be erratic or drift over time. If the sensor linkage is loose or bent and not giving a good reading, repair or replace. Whenever a linkage sensor is repaired or replaced, rerun the linkage position sensor calibration in ET or through the machine display. After the sensor calibrations are complete, Caterpillar recommends rerunning the full and empty bucket payload calibration and the simple calibration.Lift Cylinder Head-End and Rod-End Pressure Sensors
The lift cylinder head end and rod end pressure sensors are used to calculate payloads when the linkage travels through the weigh range. These sensors have active diagnostics and send a Pulse-Width Modulated signal, however it is possible that signal noise or an erratic signal too short to be detected by the ECM could affect the payload reading. There is no direct calibration of the lift cylinder pressure sensors, however Caterpillar recommends rerunning the full and empty bucket payload calibration and the simple calibration if sensors are replaced.Implement Start Mod and Max Mod Calibrations
If the implement valve calibration currents have been modified since the last valve calibration, it is possible that functions like snubbing and kickouts are not working correctly and could affect accuracy. When in doubt or when the valve currents have been modified, rerun the implement valve calibrations. After the valve calibrations are complete, Caterpillar recommends rerunning the full and empty bucket payload calibration and the simple calibration.Accelerating & Digging in the Weigh Range
The default start of the weigh range is 50% cylinder travel and the default size of the weigh range is 15%. If the start of weigh is lowered from the