Inspect the condition of the main line switch before inspecting any part of the controller.
opening the main line switch should remove all power from the controller. Examine all relays,
switches, contactors, control circuit rectifiers, transformers, capacitors, reactors, etc. Any
excessively worn or burned contacts, broken connectors, broken or cracked resistors, or tubes
should be replaced. All fuses should be one time fuses and should not have any shorting wires.
Check for cleanliness and for accumulation of combustible materials on any parts.
16.6 INSPECTION OF THE CARRIAGE
The carriage serves as the local carrying medium, transporting material to and from storage
locations. (See Figure 16-12). It is raised and lowered between the masts by means of wire ropes
reeved to the hoist drums via the cranes upper end tie. Guide rollers are provided on each side of
the carriage, allowing it to move up and down the mast with a minimum of friction. A number of
limit switches and photo-electric scanners are used on the carriage assembly, to monitor the
movement of the crane and the position of the load.
16.6.2 Guide Rollers
Check the carriage guide rollers for cracks or chipping. Inspect the rollers for flat spots and
any unusual wear patterns or markings. Check the roller bearings for adequate lubrication.
Examine the rollers for excessive float. If any of the above conditions exist, the rollers must be
repaired or replaced.
16.6.3 Carriage Spring
Check the carriage spring adjustments. (See Figure 16-13). The centering springs should be
adjusted to maintain a 3/16" gap between the jaw and the rail.
16.6.4 Shifter Assembly
Inspect the side shifter assembly. (See Figure 16-14). The side shifter or shuttle is a
telescoping device mounted on the carriage and extending in either direction in order to place or
retrieve a load. Examine the sprockets and chains for signs of wear, misalignment, or other