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Marine Windlass

Windlass is ship machinery to retractable anchor and chain on board. Using steam engine, electric motor and hydraulic motor as power. Usually installed on the first deck of ship. The trend of its development is to achieve operation, anchoring, mooring and automatic mooring for a unit. According to the driving form can be divided into: manual, electric, hydraulic.

Windlass mainly by base, bracket, chain wheel, brakes, sprocket, gear box, control system (manual windlasses except ) and other components, electric windlass motor and hydraulic windlass with hydraulic pump station.

The main specifications of windlass include diameter of anchor chain, anchor nominal speed, rated load, support load, speed, power system voltage etc.

Windlass in ship installation to ensure the chain and sprocket wrap angle is 117 - 120 degrees.

Anchor windlass requirements

The windlass is machinery for anchoring and anchor drop, also used as mooring. There are some requirements for windlass:

1) the anchor should be independent of original drive power

2) the anchor rating SWL should be not less than 41.68d2N (4.25d2kgf), when d<25mm rating SWL should not be less than 36.8d2N (3.75d2dgf), D for chain diameter, the unit is mm. The average speed should be no less than 9m/min when the rated tension is used.

3) windlass under rated tension and speed should be continuous working 30min, and in not less than 1.5 times overload tension should be continuous work 2min; in addition to anchor windlass should be equipped with overload protection device, overload can be transferred to the medium speed operation.

4) anchor chain sprocket on the brake should be reliable, 45 per cent of the brake chain fracture load pull (when freedom anchor drop at speeds of 5~7.5m/s can still stopped falling chain); between windlass chain wheel and axle load should be a clutch, brake and clutch manipulation is convenient and reliable; windlass operation should be along the reverse rotation and smoothly and rapidly.

5) windlass installation shall ensure the cable leads three eyes (hawsepipe, chain, sprocket) in line.

There are horizontal and vertical anchor windlass, the general ship use horizontal anchor windlass. And vertical anchor windlass also called anchor capstan and its power below deck, to save the deck area , naval ships widely use vertical anchor windlass. Recent large ships, because the anchor windlass size is too large, the bow deck to accommodate and operation of adverse, therefore, using vertical anchor windlass.

Classification of marine windlass

According to the driving mechanism of energy points: 
  • manual windlass, 
  • anchor steam windlass, 
  • electric windlass (DC electric windlass, AC electric windlass) and 
  • hydraulic windlass (high pressure type anchor hydraulic windlass, pressure type anchor hydraulic windlass, pressure type anchor hydraulic windlass.

According to the center line direction: 
  • horizontal windlass, 
  • vertical anchor chain wheel capstan

According to the arrangement: 
  • double gypsy windlass, 
  • single gypsy windlass, 
  • combined windlass

Characteristics of various windlass

Manual windlass

The weight does not exceed 250kg of the anchor, according to the working conditions, if it can be suitable for use, you can configure the manual anchor. Manual windlass is only used in inland river small ship, it should prevent the handle from injuring people.
Steam windlass

Steam windlass has been widely applied in the steam ship, currently used for large tankers. The firm structure, reliable work, no dangers caused by fire, but the steam engine efficiency low, huge structure, laying on the deck for a long pipeline heat loss, deck steam engine cylinder pressure is generally not more than 0.8MPa, operation management problems, in winter when the weather is cold, before use to fully warm engine, to discharge the residual water.

Electric windlass

Electric windlass is currently the most widely used in the ship.

According to the power system of the ship, the electric windlass has DC motor and AC. DC motor speed control characteristics, high efficiency, but the high cost of the initial set, the brush should be regularly maintained.

AC motor speed adjustment performance is poor, usually only have a variable speed, depending the motor and windlass a set of speed reducer to get a number of speed grades. This set of gear reducer, due to the need of a large reduction ratio, and consider transmission and working reliability of windlass and other issues, the structure is more complex, the weight and size of the area occupied by larger deck.

Reducer transmission device often used spherical worm and worm gear transmission, spur gear transmission, planetary gear transmission and other transmission mode. Generally speaking, the planetary gear reduction transmission mechanism of light weight, small size, high transmission efficiency, maintenance is simple, so the current application more.

Hydraulic windlass

Hydraulic windlass is mainly rely on hydraulic device to carry out and control the action. Hydraulic windlass because of its hydraulic energy from motor driven oil pump device, also known as electric hydraulic windlass. It has the following characteristics:

(1) with a good speed control performance of the DC motor.

(2) usually uses the low speed high torque hydraulic motor, low speed, large output torque, no longer need to set up a huge mechanical reducer, can directly drive a chain wheel.

(3) hydraulic drive with self -brake dynamic performance, work safety and reliability.

(4) compact structure, small weight and size of unit power. .

(5) easy to operate, maintenance is simple.

(6) easy to realize remote control and automation

For large, high degree automation ship, the use of hydraulic windlass on the ship's economy, reliability is more favorable. Hydraulic windlass can also be driven by high speed oil motor. High speed oil motor is commonly used in the structure of the bending shaft type axial plunger oil motor and the radial piston (or steel ball) type oil motor or vane type oil motor. Oil motor itself is small, need to set up a larger gear reducer.

Horizontal windlass

The chain wheel shaft of the horizontal windlass and the center line of the reel shaft are parallel to the deck, and the whole set of anchor equipment is installed on the deck, operation management is convenient. But equipment occupies a large area, and easy to suffer from wind and wave erosion. General merchant ships more use of horizontal anchor.

Vertical windlass (capstan)

The shaft center line of the chain wheel shaft and the center line of the vertical windlass is perpendicular to the deck. The power system and transmission mechanism are placed deck below, only the sprocket and drum extends out of deck, guided by a vertical shaft. No horizontal windlass occupied deck area and easy to suffer wind erosion of the shortcomings, but chain wheel vertical shaft under large bending moment, management is not very convenient.

Double gypsy windlass

One or two drive motor in center, two anchor chain are arranged on the left and right sides. If the original motivation and chain wheel sharing a base is known as integrated windlass, if separated from the prime mover and chain wheel base is known as ordinary separation type windlass.

Single gypsy windlass

An drive motor only to configure an anchor chain wheel, drum and brake device, composed of independent units. Unilateral type windlass arranged in both sides of the bow. According to the location of the different, there is the right and left .

Combine windlass

Two sets of single gypsy windlass combined to form a whole. The chain wheel on either side can by any prime mover driven, two sets of the original motivation, enhance the vitality of the windlass.

Automatic brake windlass

Anchor and chain free falling property. The deeper anchoring, the faster fall is. When anchored in deep water, the anchor encountered hard water bottom, impact very large, prone to damage. Accelerate speed of the whereabouts, chain sprocket pounding, an increase of possibility "slipping chain hopping", and may produce a spark. For large ships, anchors and chains, weight is very big, general windlass brake equipment has not effectively control speed of the whereabouts, especially deep sea anchor operation, long time and strenuous friction will lead to windlass heating and burning. In this case, it is necessary to use Automatic brake windlass.In modernization large tankers, often using pneumatic steam windlass.


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