CHAPTER 7-1
Construction and Installation
Section 7-1.1: Load Ratings and Markings
7-1.1.1 Basis. Hoist ratings are dependent upon
such factors as applied power, amount of rope wound
on the drum, drum size, and structural competence of
the various hoist components and mounting methods.
7-1.1.2 Load Ratings. Load ratings shall be the
manufacturer's recommended single rope pulI in pounds
(kilograms) at a specified rate of speed on a given
size drum and prescribed number of layers of rope.
7-1.1.3 Markings. Hoists are to be marked with
the following identifications for each drum:
(a) load rating;
(b) drum size consisting of barrel diameter, barrel
length, and flange diameter;
(c) rope size(s);
(d) rope speed in feet per minute (meters per second);
(e) rated power supply.
Section 7-1.2: Construction
7-1.2.1 General. Hoists shalI be designed and constructed
to meet all stresses imposed on their frames
and components under normal operating conditions
when properly installed and with handling loads not
exceeding the manufacturer's load ratings. Welding
shall conform to recommended practices of ANSIIA WS
DI4.3.
7-1.2.2 Hoist and Swinger Mechanisms
(a) Drum assemblies shall be provided with power
and operational characteristics to perform all lifting,
lowering, and swinging functions when operated at
rated load.
(b) Where maximum rated loads are being lowered
for long distances, power controlIed lowering usually is
necessary to reduce the demand on the brake. Additional
cooling provisions may be required on fluid transmissions
or torque converters.
(c) The drum capacity shall accommodate the recommended
rope size and length necessary to perform
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the specified function required for the load-handling
equipment with which the hoist is used.
( I) No less than two full wraps of rope shall
remain on the drum with the tackle system of the loadhandling
equipment extended to its maximum reach.
(2) Each drum end of the rope shalI be anchored
by a clamp attached to the drum, or by a socket
arrangement approved by the hoist or rope manufacturer,
providing for attachment of rope to the drum.
(3) Drum flanges shalI extend a minimum of 1/2
in. (13 mm) over the top layer of rope at all times.
(d) Diameter of the drum shall provide first layer
rope pitch diameter of not less than the following:
( 1) 18 times the nominal diameter of the rope
used for service such as lifting or lowering a load
(hoisting);
(2) 15 times the nominal diameter of the rope
used for service such as raising or lowering a boom
(booming);
(3) 15 times the nominal diameter of the rope
used for service such as barge anchor handling;
(4) 15 times the nominal diameter of the rope
used for swingers.
(e) Drums which hold items such as loads and booms
suspended for a considerable time shall be provided
with a ratchet and pawl or equivalent holding means,
other than a brake, which shall be operable from the
operator's station.
(f) All hoist and swing drives should be capable of
starts and stops with variable acceleration and deceleration
required in normal operation.
7-1.2.3 Brakes
(a) Each load hoist mechanism shalI be equipped
with at least one brake having a torque rating not less
than that produced by 125% of the maximum rated
line pulI at the point where the brake is applied. The
maximum rated line pulI at each rope layer on the
drum shall be considered in determining this rating.
(b) When power operated brakes having no continuous
mechanical linkage between the actuating and braking
means are used for controlling loads, an automatic