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发表于 2016-1-15 10:53
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来自： 中国福建福州
Mooring Winch Brake Holding Test
Scope:
- The brakes should be tested to prove that they render at a load that is equivalent to 60% of the
line's MBL.
or
- The brakes, if fitted with new liners, to be set to render at 80% of the line's MBL, but have the
capability to be adjusted down to 60% of the line's MBL.
Test Specification:
A winch test specification to be prepared, incorporating specific instructions for setting up the test gear,
preparation of the winch for testing, setting of the winch brakes, application of the test load, revision of
torque wrench or hydraulic pressure readings if required, and recording of test results.
Supervision of Testing:
All winch testing is to be carried out under the supervision or in the presence of a senior officer
designated by the Master or Chief Engineer or a repair superintendent familiar with the test procedure
and the operation of the winches.
Test Equipment:
Typical equipment for testing the brakes similar to the one on figure below or compatible, usually
including the following items:
 Lever usually consisting of two pieces of bar, as shown on the sketch. The lever is secured to the
drum of the winch by means of bolts furnished with the test kit, and fitted through holes
provided in the drum flange.
 Hydraulic jack with pressure gauge
 Foundation to be placed under the hydraulic jack for the purpose of distributing the load into
the deck structure.
Typical Winch Brake Test Equipment
The lever should be lightweight for easy handling. Testing can be further simplified by reducing the lever
to slightly more than the drum flange radius and placing the jack directly on the winch foundation.
A graphic depicting such a test arrangement is shown in below. In place of the heavy lever, a simple
fitting attached to the drum flange suffices. The higher jack loads may pose a problem for existing
equipment, but provision for this method can easily be incorporated into new equipment.
Simplified Brake Test Kit
Method of Testing:
The testing arms are bolted to the flange of the winch drum with the hydraulic jack pressed under the
end of the arms at the designated location and resting on supports. The brake is set as recommended in
the test specification. If the winches are set manually a torque wrench should be used. If they are set
hydraulically the pressure gauge should first be calibrated.
Before testing, the detailed instructions for testing included in the test specification should be reviewed
and the equipment prepared accordingly. The instructions will include:
• The values for torque wrench or pressure gauge fitted for setting up the brakes
• A curve or table relating hydraulic jack test pressure to line pull
• Hydraulic jack pressure at which the brake is designed to render.
With the winch prepared for testing, the testing gear securely in place and winch brakes set in
accordance with the recommendations, pressure is applied to the hydraulic jack. The winch drum is tobe
carefully observed. At the first sign of movement, the hydraulic pressure applied to the jack is recorded
and the following action taken:
• If slippage occurs at a pressure less than designed, the brake should be tightened or repaired and
jack pressure reapplied
• If the recorded pressure corresponds to the design pressure, the jack should be released and the
test gear removed
• If slippage does not occur at the design pressure, the brake setting should be adjusted so the brake
can render at the design load.
Once the brakes are tested and calibrated, the proper setting should be recorded. In case of
conventional screw brakes, a tag should be attached stating the proper torque. For spring-applied
brakes, the spring compression distance should be recorded and the spring adjustment mechanism
secured with a seal.
The provision of a stopper arrangement on the tightening screw, such as placing locking nuts on the
threaded end - See Figure below- is NOT acceptable due to safety reasons. It will impede the brake
setting and reduce the brake holding load.
Improper Fitting of Locking Nuts to Brake Tightening Screw
Brake Holding Capacity:
The primary brake should be set to hold 60% of the mooring line's MBL. Since brakes may deteriorate in
service, it is recommended that new equipment be designed to hold 80% of the line's MBL, but have the
capability to be adjusted down to 60% of the line's MBL. A band brake holding capacity of 80% MBL with
the rope on the first layer is also required by Lloyds, DNV and ISO Standard 3730. If a brake of an
undivided drum is set to hold 80% MBL on the first layer, it will hold approximately 65% MBL on the
third layer.
Marking the Correct Brake Tension:
The point of marking the correct tension is to avoid the brake being applied too hard, which might
result in the rope parting before the brake renders.
Vessels equipped with screw-type mooring winch brakes are to fabricate, using jubilee clips and plate
metal, preferably brass, the arrangement shown in the picture below: |
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