Bearings, couplings, bushings, and seals are required to be fitted
according to the manufacturer's recommendations.
Single keys must be fitted to the Class 2 requirements of ANSI B17.1.
When it is impractical to re-machine the key seat or the keyway, the key cross
section may be modified/stepped and custom fitted for the required fit. Double
keys may be fitted to the less accurate Class 1 criteria.
Welding. All welding should comply with the applicable requirements of
AWS D1.1 or D1.14. Otherwise, the welds must be designed to provide the required
design factors of mechanical components. The strength of the weld metal is always
greater than the strength of the base metal; however, the required design factor
is based on the strength of the base metal.
Hydraulic Systems. With the possible exception of the reservoir, all
hydraulic system components are standard commercial products with specific
pressure ratings. Hydraulic hoses and tubing commercial ratings provide a design
factor of 4.00 based on their bursting pressure. Various SAE standards establish
the requirements for hydraulic hoses, tubing, fittings, and assorted components.
All selected hydraulic components may be used at their commercial rating;
components which do not comply with the SAE standards or are not included in them,
must be approved by NCC. Corrosion resistant pressure tubing is required on all
installations exposed to the weather and on floating cranes. The standard
material for housings of most hydraulic components is gray cast iron, with no
option for any other material. Manufacturer's ratings of components should be
accepted at full value. (It should be noted that hydraulic power systems are
always designed with pressure limiting relief valves, which provide positive
protection against any transient pressure spikes.)
The nominal operating pressure of hydraulic drive (power) systems of
custom designed hoists should not exceed 2000 psi. Hydraulic fluid should comply
with the recommendations of the components' manufacturer and must be compatible
with the seal materials. Only petroleum based hydraulic fluids may be used in the
must be approved by NCC.
Secondary hydraulic systems, such as brakes and various actuators, should
be standard commercial products and should be used at their full commercial
Mechanical-Electrical. Mechanical-electrical components of cranes are
considered to be: electro-mechanical shoe and disc type brakes, hydraulically
applied shoe brakes (thrusters), caliper disc brake systems, clutches, and gear
motors. These components, as applicable, are required to be integrated into the
crane's electrical system.
Sizing and Selection of Components. Following are the criteria to be
utilized for the sizing and selection of mechanical-electrical crane components.
Except as stated otherwise, all components are required to be the industrial or
marine grade products of manufacturers specializing in the production of this type
Mechanical Criteria for Brakes. On a portal crane, two
electro-mechanical shoe brakes, each rated at 130 percent of rated motor torque
(minimum), are required to be provided for each hoist drive mechanism.