15 August 2002
Interchangeability. To obtain maximum operational efficiency and
economy, portal cranes should be interchangeable among the various yard facilities
they might serve. As far as possible, incorporate the following features into a yard
crane track layout:
All portal crane tracks should have the same gage as other yard crane
When track consists of two pairs of rails, lay each pair at standard railroad
Interconnect the various crane tracks.
Provide spur track turnouts for repairing cranes.
Provide a sufficient number of switches and passing tracks to permit
individual cranes and other rolling stock to travel without interrupting the
operation of other cranes.
Refer to MIL-HDBK-1005/6 Trackage for crane track alignment procedure.
Weight and Materials Handling Equipment. Small capacity locomotive
or motor truck cranes are assigned to graving dock activities to supplement portal
cranes. The locomotive cranes operate on the standard gage railroad track.
Portal Cranes. These cranes are constructed on portal frame bases that
travel on wide gage (6.096 to 9.144 m) (20 to 30 ft) tracks. Refer to MIL-HDBK-1038,
Weight Handling Equipment. Capacities and reach should be as specified for each
Clearances. Clearances must be such as to permit complete rotation
(360 degrees) without interference with the ship in drydock, buildings, or other
structures. Cranes and track layout must be carefully studied to ensure adequate
clearances in the way of overhanging deck structures of aircraft carriers. For carrier
docks, provide two sets of tracks on each side of the dock, one of conventional
arrangement with rail near the edge of the coping, and one outboard at a distance
sufficient for the crane to clear the flight deck of the carrier.
Power Drive. Portal cranes should, in general, be powered by self-
contained diesel electric drive.
Personnel Facilities. Provide facilities such as lavatories, showers, and
lunchrooms near the graving dock.
Lavatories. Provide lavatories fairly close to the graving dock. They
should contain toilets, urinals, washbowls, showers, first aid equipment, and perhaps
equipment lockers. They should be large enough to accommodate the normal
complement of the yard crew working in or around the graving dock, and the crew of