1) Dead load, trolley dead load, 200 percent of the live load
(container weighing 89,600 to 112,000 pounds), lift system (head block, spreader,
wire ropes, and sheaves), and 55 mph operating wind applied from either end and
perpendicular to the boom.
2) Dead load, trolley dead load, live load, lift system, and
Collision force is due to the full impact of the crane hitting its end
stops or the bumpers of another crane, or of the trolley hitting its end stops, at
rated speed but with the power off. The energy absorbing or decelerating
characteristics of the bumpers are considered in determining the collision force.
3) Dead load, trolley dead load, live load, lift system, and
Stowed Configuration. In the stowed configuration the boom is
raised and locked against the A-frame boom stops, the trolley is locked on the
main beams near the land side gantry leg, but the gantry is not tied down. The
resultant of all forces must be within 80 percent of the distance from the
gantry's geometric center to either rail or the main gudgeon axis, as applicable.
Two cases are considered:
1) Dead load, trolley dead load, lift system, and non-operating
2) Dead load, trolley dead load, lift system, and seismic load.
Mobile Cranes. Stability criteria for mobile cranes (and locomotive
cranes) are detailed in ASME B30.5 and NAVFAC P-307, Management of Weight Handling
Equipment; it addresses the margins of stability, determination of load ratings,
and site conditions. Additional requirements for test apparatus, set-up, and test
methods are provided in SAE J765. These standards are followed by the commercial
manufacturers of mobile cranes. These cranes may be used at their full load
ratings for all GPS applications. For SPS applications, various local
restrictions (in the form of policies and procedures) are usually imposed.
Gantry and Semi-Gantry Cranes. There are no established/generally
accepted stability criteria for these cranes. These cranes may be designed with
either a load block and hook for general applications, or with a head block and
spreader for container handling. (Semi-gantry cranes are not normally used for
container handling.) The resultant of all forces is translated to the plane of
the tipping axis. NCC considers three cases for each application.
For cranes with a load block:
1) Dead load, trolley with rated hook load in any position on the
bridge girders, and 40 mph operating wind applied perpendicular to the bridge
girders. The resultant of all forces and moments must be within 70 percent of the
distance from the crane's geometric center to the main gudgeon pin axis.