16.6.7 Scanning System
Banner modulated "LED" scanners are used for both the carriage and aisle address systems.
(See Figures 16-16 and 16-17). Position is sensed as the crane or carriage passes each rack
position. The information revealed by the sensors is relayed to the control panel indicator lights.
The lens of each unit should be free of dirt or dust. The frequency of cleaning required will be
determined by the conditions in the area the crane operates.
16.7 INSPECTION OF THE UPPER END TIE
16.7.1 Upper Guide Rollers
Inspect the upper guide rollers. (See Figure 16-18). The upper guide rollers guide the top end
of the crane along a rail that is usually suspended from the top of the storage rack. They serve
only to guide the crane. They are not load carrying devices. Inspect the guide rollers for cracks
or chipping. Examine the rollers for flat spots and any unusual wear patterns or markings. Also
check the roller bearings for adequate lubrication and excessive float. If any of the above
conditions exist, the rollers must be repaired or replaced.
16.7.2 Sheave Assemblies
Inspect the sheave assemblies. (See Figure 16-19). The sheave assemblies are mounted in the
upper end tie. The purpose of the sheaves is to provide a means through which to reeve the hoist
rope from the hoist drums to the carriage. The rope should ride over the sheave wheel, which is
free to rotate as the rope is played out and retrieved. Inspect the bearings for damage, excessive
wear or looseness. Examine the sheave wheel for excessive or uneven wear in the cable groove.