BI616938
Bucyrus International, Inc. 8750 Walking Dragline
HOIST/DRAG LIMIT CALIBRATION An encoder attached to the end of the hoist and drag drum shafts continually monitors the drum position during operation. As the bucket nears the preset limits, reference is gradually removed until the drum rotation is stopped. To prevent tight-lining or pulling the bucket into the boom, the sum of the hoist and drag ropes payed out in monitored. If this sum reaches a preset length, the hoist or drag functions will be slowed, then stopped. The limits must be recalibrated after changing the ropes or anytime maintenance is performed which alters the encoder versus drum rotation. Recalibration is required on the function, hoist or drag, being serviced. There are two calibration points on each rope. The first is with 1.5 dead wraps on the drum. The second is with the ropes at 10 meters from either the point sheaves or the fair lead. Rope length is calculated from the calibration points and the active rope length is used to determine limit status. There are three limits at each end of travel. Slowdown limit is the first. When this point is passed the reference is starting to be limited linearly toward the stop limit. Stop limit is the second, at this point the reference is reduced to zero. The last limit is the final limit, when this is reached the brakes are set and the drive is turned off. The first two limits can be exited by reversing the master switch to the opposite direction. The final limit needs to be exited with the limit bypass switch. Limits are set using the Hoist/Drag Limit Calibrate screen. A password is required to access this screen. On this screen limits are defeated and maximum speed is reduced. Rope installation should be done using the Rope Reeving Screen. A password is required to access this screen. On this screen limits are defeated and maximum speed is reduced.
Feb. 2007
45
Manual No. 10348 - Rev. 2
