OCIMF_Mooring_Equipment_Guidelines_(Second_Edition)

7.5.2.6 Sensi/ivily in Reeling Direclion

A band brake is designed to work in one direction only. Therefore the line must always be reeled
correctly onto the drum. Tbe line is properly reeled if it is pulling against the fi)(ed end of the brake
strap.

Disc brakes work equally well in either direction.

Some winches are equipped with so-caUed hydraulic-assist brakes. With this type, a hydraulic cylinder

sets the brake. A pressure gauge connected to the cylinder allows the brake 10 be applied with the

proper force, predetermined during brake testing. Once the brake is applied with the hydraulic assist,

the load is transferred to the mechanicnl linkage by tightening the handwheel until the pressure in

the assist cylinder starts to drop. Although this feature eliminates the need for a torque wrench, the

brake has the same dIawbacks as the mechanical screw brake mentioned above. This type of brake

is therefore not recommended for new ships.

Since hydraulic-assist brakes and somc spring-applied brakes with hand hydraulic release look similar,

it is very imponant that operators study the instruction book for their particular ship's inSlaUation.

7.5.3 Disc Brakes

Disc brakes are less sensllIve to friction changes than band brakes and are therefore bell er suited

for winch brakes. Disc brakes are in wide use for input brakes (see Section 7.5.4), but few wincb

manufacturers offer them for drum brakes. If available, they should be seriously considered for ncw

construction.

Disc brakes do not have the other drawbacks mentioned earlier, but tbis is of secondary importance,

since band brakes can be improved by spring application and proper operation. Spring application

is also recommended for disc brakes because of the foolproof simple operation that it permits.

7.5.4 Input Brakes

Most hydraulic and electric winches are provided with spring-applied brakes at the drive moior. Tbey

are automatically applied by springs when the control lever is in neUlral and automatically released

when the control \ever is in the heave or reodering position (when the motor is powered). ISO

Standard 3730 re.quircs automatic brakes with a holding capacity of 1.5 times the rated load for all

electric wincbes.

For single drum winches (one drum pcr drive), input brakes could serve as the primary brake an.d

would eliminate the need for separate drum brakes. However, if the winch is also provided with a

warping head, a drum bra.ke and dog clutch would still be reqnired to allow use of the warping

head while tnc drum is held stationary.

Multiple-drum winches always require a brake for each drum.

Most input brakes are OOt rated to serve as a primary brake due 10 strength limitations of the

gears. If this is the case, once the ship is moored tbe drum must be set on the drum brake and

disengaged from the drive by means of the dog clu[cb. If the drum is left engaged and [he drum

brake is set, both brakes will work in. unison. (rated holding capacity is directl.' additive). The

combined holding capacity will exceed 100070 of the line's M BL, an undesirable result for reasons

explained earlier.

7.5.5 Winch Broke Testing

RegardJess of tbe brake type, periodic testing is essential to assure a safe mooring. Tbe following

provides a guide for testing of mooring winc·h brake!;);