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Cargo handling equipment

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The crane housing, which is a welded construction on a rigid baseplate, ... The system is also provided with a preheater for heating the oil in cold weather. – PowerPoint PPT presentation

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Title: Cargo handling equipment


1
Lesson 19
  • Cargo handling equipment
  • (??????)

2
  • The various items of machinery and equipment can
    be found outside of the machinery space.

3
  • These include deck machinery such as mooring
    equipment(????), anchor handling equipment(????),
    cargo handling equipment and hatch covers(???).

4
  • Other items include lifeboats(???) and
    liferafts(???), emergency equipment, watertight
    doors, valve actuator, stabilizers(????) and bow
    thrusters(?????).

5
  • The cargo handling equipment will now be
    described.

6
  • Cargo winches are used with various derrick(??)
    systems arranged for cargo handling.

7
  • The unit is rated according to the safe working
    load to be lifted and usually has a double speed
    provision(??) when working at half load.

8
  • In the cargo winch, spur reduction gearing
    transfers the motor drive to the barrel shaft.

9
  • A warp end(???) may be fitted for operating the
    derrick topping lift (???) (the wire which
    adjusts the derrick height).

10
  • Manually operated band brakes may be fitted and
    the drive motor will have a brake arranged to
    fail-safe(????), i.e. it will hold the load if
    power fails or the machine is stopped.

11
  • A derrick rig(??) is known as union
    purchase(??????).

12
  • One derrick is positioned over the quayside and
    the other almost vertically over the hold(??).

13
  • Topping wires fix the height of the derricks and
    stays(??) to the deck may be used to prevent fore
    and aft movement.

14
Topping wires
Derricks
Cargo handling wires
Winches
15
  • Cargo handling wires run from two winches and
    join at the hook.

16
  • A combination of movements from two winches
    enables lifting, transferring and lowering of the
    cargo.

17
  • Cranes have replaced derricks on many modern
    ships.

18
  • Positioned between the holds, often on a
    plateform which can be rotated through 360, the
    deck crane provides an immediately operational
    unit requiring only one man to operate it.

19
  • Various types of crane exist for particular
    duties.

20
  • In a general cargo crane, three separate drives
    provide the principal movements

21
  • a hoisting(??) motor for lifting the load, a
    luffing(??) motor for raising or lowering the
    jib(boom), and a slewing(??) motor for rotating
    the crane.

22
  • The crane is usually mounted on a pedestal(??) to
    offer adequate visibility to the operator.

23
  • For occasional heavy loads, two cranes can be
    arranged to work together.

24
  • The operating medium for deck crane motors may be
    hydraulic or electric.

25
  • The use of hydraulic drives in cranes, winches
    and similar equipment is now accepted as a
    conventional method of drive in many case.

26
  • Many reasons can be suggested for the use of
    hydraulic systems in marine engineering

27
  • a) A convenient method of transferring power over
    relatively long distances from, say, a central
    pump room to remote operating sites.

28
  • b) Fully variable speed control of both linear
    and rotary motion, with good inching capability
    and smooth take up of load.

29
  • c) High static forces or torques can be achieved
    and maintained indefinitely(????).

30
  • d) Complete safety and reliability is assured
    under the most difficult environmental
    conditions

31
  • overload conditions are safeguarded by using a
    relief valve to limit maximum output torques or
    forces.

32
  • The wide range of high torque, low speed motors
    are available for driving winch drums directly so
    dispensing with(??) the need to fit reduction
    gearing.

33
  • Motors of this type are more common on larger
    cranes where reduction gearboxes would be
    expensive.

34
  • All fixed capacity motors, whether high or low
    speed, require a high flow at low pressure to
    obtain high light hook speeds and consequent
    short cycle times.

35
  • With large cranes this can become an
    embarrassment and one solution with low speed
    motors is to use the two speed type to double the
    speed and half the output torque at light hook
    load.

36
  • High speed motors with reduction gearing have the
    advantage that the brake can be mounted on the
    high speed shaft and so be much smaller and
    cheaper.

37
  • Because of the availability of standard low cost
    gearboxes this arrangement is popular on light
    cranes.

38
  • Variable capacity axial piston motors have the
    important advantage that light hook speeds can be
    increased up to four times from a given oil flow
    by reducing the motor capacity to 25 per cent of
    the maximum.

39
Hydraulic Crane
  • The hoisting of the cargo is effected by a
    hoisting winch driven by a hydraulic motor that

40
  • that provides a constant torque in both
    directions of rotation and at all speeds within
    the regulation range of the motor.

41
  • The winch is equipped with a mechanical belt
    brake that acts on the outside of the rotating
    motor housing.

42
  • During operation, the brake is released by means
    of oil pressure which compresses a spring.

43
  • The crane jib is raised and lowered by means of a
    luffing winch which is constructed in a similar
    manner to the hoisting winch.

44
  • The pumps are axial piston pumps and are driven
    by a common 3-phased synchronous motor(???????)
    at a constant speed of rotation.

45
  • The capacity of the pump is changed by turning
    the swashplate.

46
  • The crane is turned by a hydraulic motor of the
    same type as that described above, in that the
    rotor turns a pinion which engages with a toothed
    ring on the crane housing.

47
  • An oil cooler is used to remove the heat
    generated in the oil during the operation of the
    crane.

48
  • The system is also provided with a preheater for
    heating the oil in cold weather.

49
  • If the temperature of the oil reaches 85oC, a
    thermostat(??????) in one of the oil lines
    switches off the electric motor.

50
  • Pressure relief valves are built into the system
    to protect the system and the crane against
    excessive loads.

51
  • All moving parts in the hydraulic system are
    lubricated by means of the oil in the system.

52
  • The crane housing, which is a welded construction
    on a rigid baseplate, contains all the mechanical
    machinery, the hydraulic system and the electric
    equipment.

53
  • The tops of the crane housing and the jib carry
    blocks(???) for wires for the hoisting of the
    cargo and the raising of the jib.

54
  • All of the blocks have enclosed ball bearing.

55
  • Both the luffing winch and the winch for turning
    the crane are operated from the same control
    handle.

56
  • A small movement of this control handle either
    forwards or backwards results in the build up of
    oil pressure in the control oil line and the
    piston in the brake cylinder releases the brake.

57
  • Movement of the control handle further than the
    position for releasing the brake starts the
    luffing winch.

58
  • The crane jib is raised or lowered by moving the
    control handle backwards or forwards
    respectively.

59
  • The speed at which the jib is raised or lowered
    is proportional to the distance the handle is
    moved.

60
  • Changes in speed are effected by changing the
    pressure of the oil that is supplied to the
    control cylinder and which regulates the pump by
    means of a servomotor(???????).

61
  • This changes the oil flow and thus the speed of
    the rotor in the hydraulic motor.

62
  • The safety system consists of a main safety
    valve two pressure reducing valves.

63
  • The slewing winch, which is almost identical to
    luffing winch, is controlled by using the same
    handle as that used for the luffing winch.

64
  • A small movement of the control handle to the
    right or left gives rise to oil pressure in the
    brake cylinder and releases the brake on the
    slewing winch.

65
  • Movement of the control handle to the right or
    left in excess of the positions that release the
    brake starts the crane moving to the right or
    left respectively.

66
  • The closed hydraulic system consists of an axial
    piston pump with variable output and a hydraulic
    motor mutually connected through oil pressure
    lines.

67
  • The amount of oil flowing through the system and
    the direction of flow are regulated by means of a
    servomotor.

68
  • When in operation, it is unavoidable that a small
    amount of oil escapes through leakage, and in
    order to compensate for these leaks the system is
    connected to a feed pump.

69
  • For pumping up, two check valves are used, and a
    bypass valve limits the pressure to 17-25 bar.

70
  • The safety system is designed for a certain
    maximum pressure, and the working pressure must
    therefore be limited.

71
  • For this reason there is included a main relief
    valve that connects the pressure side of the
    system to its suction side if the permissible
    pressure is exceeded.

72
  • A double check valve with a common spring ensures
    that the relief valve always operates, regardless
    of which of the oil lines is the pressure side.

73
Reading materials
  • Mooring equipment
  • (??,????)

74
  • Winches with various arrangements of barrels are
    the usual mooring equipment used on board ships.

75
  • It usually consists of a driving motor, a
    reduction gear, a winch barrel or drum and one or
    two warp ends.

76
  • The winch barrel or drum is used for hauling
    in(?) or letting out(?) the wires or ropes which
    will fasten the ship to the shore.

77
  • The warp end is used when moving the ship using
    ropes or wires fastened to bollards(???) ashore
    and wrapped around the warp end of the winch.

78
  • The motor drive is passed through a spur gear
    transmission, a clutch(???) and thus to the drum
    and warp end.

79
  • A substantial frame supports the assembly and a
    band brake is used to hold the drum when
    required.

80
  • The control arrangements for the drive motor
    permit forward or reverse rotation together with
    a selection of speeds during operation.

81
Mooring Winch
  • Mooring winches provide the facility for
    tensioning(??, ???) the wire up to the stalling
    capacity of the winch, usually 1.5 times full
    load,

82
  • thereafter the load is held by the prime mover
    brake or barrel brake when the power is shut off.

83
  • The winch cannot pay out wire unless the brake is
    overhauled or recover wire unless manually
    operated, thus wires may become slack.

84
  • Automatic mooring winches provide the manual
    control previously described but in addition
    incorporate control features such that,

85
  • in the 'automatic' setting, the winch may be
    overhauled and wire is paid off the barrel at a
    pre-determined maximum tension

86
  • also wire is recovered at a lower tension should
    it tend to become slack(??).

87
  • Thus there is a certain range of tension,
    associated with each step of automatic control,
    when the wire is stationary.

88
  • It is not practical to reduce this range to the
    minimum possible as this result in
    hunting(??,???) of the controls.

89
  • It should be noted that the principal reason for
    incorporating automatic controls with the
    features described is to limit the render(??,?)
    value of the winch and avoid broken wires

90
  • also to prevent mooring wires from becoming
    slack.

91
  • Load sensing devices are used with automatic
    mooring winches, e.g. spring-load gearwheels and
    torsion bars are widely used with steam and
    electric winches

92
  • fluid pressure sensing either steam or hydraulic
    oil pressure, is also used where appropriate.

93
  • The majority of automatic mooring winches are
    spur geared to improve the backward efficiency of
    the gear train(???) for rendering,

94
  • the gearing and bearings being totally enclosed
    and lubricated from the oil sump.

95
  • On larger mooring winches where a barrel brake is
    fitted, it is now common practice to design the
    brake to withstand the breaking strength(???????)
    of the mooring wire.

96
  • Worm geared (?????) automatic mooring winches are
    uncommon as the multi-start(??) feature required
    to improved gear efficiency reduces the advantage
    of worm gear i.e. the high gear ratio.

97
  • B. Anchor handling equipment
  • (????)

98
  • The windlass(??) is the usual anchor handling
    device where one machine may be used to handle
    both anchors.

99
  • A more recent development, particularly on larger
    vessels, is the split(???) windlass where one
    machine is used for each anchor.

100
Cable lifter
Spurling pipe
Anchor
Chain or cable locker
101
  • The rotating units of a split windlass consist of
    a cable lifter(???) with shaped snug(??) to grip
    the anchor cable,

102
  • a mooring drum for paying out or letting go of
    mooring wires and a warp end for warping duties.

103
  • Each of these unites may be separately engaged or
    disengaged by means of a dog clutch(?????),
    although the warp end is often driven in
    association with the mooring drum.

104
  • A spur gear assembly transmits the motor drive to
    the shaft where the various dog clutches enable
    the power take-off.

105
  • Separate band brakes are fitted to hold the cable
    lifter and the mooring drum when the power is
    switched off.

106
  • The cable lifter unit is mounted so as to raise
    and lower the cable from the spurling pipe(???),
    which is at the top and center of the chain or
    cable locker(???).

107
  • Anchor capstans(????) are used in some
    installations where the cable lifter rotates
    about a vertical axis.

108
  • Only the cable lifter unit is located on deck,
    the driving machinery being on the deck below.

109
  • C. Preliminaries(????) for operating the
    hydraulic deck machinery

110
Filling the deck machinery with oil
  • Oil specially made for operation of hydraulic
    pump, hydraulic motor and hydraulic equipment
    should be used.

111
  • In case such oil is not available, turbine oil of
    a good quality may be used.

112
  • Use of water, light oil, heavy oil, animal or
    vegetable oil and also ordinary machine oil is
    strictly prohibited.

113
  • Leakage of oil or stick of the moving parts of
    pumps will be caused by less viscosity and
    excessive friction losses or noise of pumps will
    be caused by higher viscosity.

114
  • When starting up the pump, viscosity of the oil
    should not exceed 2000cst, but it shall always be
    over 15cst.

115
  • After checking up the oil, fill the system as
    following

116
  • 1. Fill the head tank with oil by the hand pump.
  • 2. Open the air vent valves (hyd. Pump, hyd.
    Motor, strainer, oil cooler, control valve,
    piping)

117
  • 3. Close the air vent valves after the system is
    filled up with oil.

118
Preliminary operation of the system
  • 1. Prior to running the pump, examine the system
    carefully and

119
  • a). Ensure that the lever of control valve is in
    neutral position.
  • b). Ensure that all the valves are set in normal
    position.

120
  • c). Confirm the suction pressure above 0.7kg/cm2,
    fill the head tank with oil if necessary.

121
  • d). Confirm the oil temperature above the value
    corresponding to the oil viscosity of 450cst.

122
  • In case of the oil viscosity above 450cst,
  • (i) Open the stop valve for warming up of pump
    unit.
  • (ii) Inch the electric motor twice.

123
  • (iii) Run the electric motor.
  • (iv) Close the stop valve.

124
  • e). Apply gear oil.
  • f). Grease up bearing metal and linkage.

125
  • 2. After satisfying the above instruction, start
    up the electric motor and run the pump, and
    expel(??) air in the circuit.

126
  • 3. Check whether noise or vibration of the
    hydraulic pump is normal or not.
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