Maintenance of Winches and Capstans
You will maintain the winch or capstan similarly.
Where band brakes are used on the drums, inspect the
friction linings regularly and replace them when
necessary. Take steps to prevent oil or grease from
accumulating on the brake drums. Check the operation
of brake-actuating mechanisms, latches, and pawls
periodically.
Inspect winch drums driven by friction clutches
frequently for deterioration in the friction material.
Check also to see if oil and grease are preventing proper
operation. Lubricate the sliding parts of positive
clutches properly. Check the locking device on the
shifting gear to see if it will hold under load.
CRANES
Cranes are designed to meet the following criteria:
1. Hoist, lower, top, and rotate a rated load at the
specified speed and against a specified list of the ship.
2. Handle 150 percent of rated load at no specified
speed.
3. Withstand a static, suspended load of 200
percent of rated load without dam or distortion to any
part of the crane or structure.
The types of cranes installed on ships vary
according to the equipment handled.
The crane equipment generally includes the boom,
king post, king post bearings, sheaves, hook and rope,
machinery platforms, rotating gear, drums, hoisting,
topping and rotating drives, and controls. Some of the
components of cranes include booms, king post
bearings, sheaves and ropes, machinery platforms,
rotating gear and pinions, and drums.
Booms
A boom, used as a mechanical shipboard appliance,
is a structural unit used to lift, transfer, or support heavy
weights. A boom is used with other structures or
structural members that support it, and various ropes and
pulleys, called blocks, which control it.
King Post Bearings
Bearings on stationary king posts take both vertical
load and horizontal strain at the collar, located at the top
of the king post. On rotating king posts, bearings take
both vertical and horizontal loads at the base and
horizontal reactions at a higher deck level.
Sheaves and Ropes
The hoisting and topping ropes are led from the
drums over sheaves to the head of the boom. The
sheaves and ropes are designed according to
recommendations by NAVSEASYSCOM. This
command sets the criteria for selection of sheave
diameter, size, and flexibility of the rope. Sufficient
fair-lead sheaves are fitted to prevent fouling of the rope.
A shock absorber is installed in the line, hoisting block,
or sheave at the head of the boom to take care of shock
stresses.
Machinery Platforms
Machinery platforms carry the power equipment
and operator’s station. These platforms are mounted on
the king post above the deck.
Rotating Gear and Pinions
Rotation of the crane is accomplished by vertical
shafts with pinions engaging a large rotating gear.
Drums
The drums of the hoisting and topping winches are
generally grooved for the proper size wire rope. The
hoisting system uses single or multiple part lines as
required. The topping system uses a multiple purchase
as required.
Operation and Maintenance of Cranes
The hoisting whips and topping lifts of cranes are
usually driven by hydraulic variable-speed gears
through gearing of various types. This provides the wide
range of speed and delicate control required for load
handling. The cranes are usually rotated by an electric
motor connected to worm and spur gearing. They may
also be rotated by an electric motor and hydraulic
variable-speed gear connected to reduction gearing.
Some electrohydraulic cranes have automatic slack
line take-up equipment. This consists of an electric
torque motor geared to the drum. These cranes are used
to lift boats, aircraft, or other loads from the water. The
torque motor assists the hydraulic motor drive to reel in
the cable in case the load is lifted faster by the water than
it is being hoisted by the crane.
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