轮机英语unit25Anchorwindlassa.ppt

Lesson 25 Anchor windlass and Mooring winch 锚机和绞缆机,Anchor handling equipment,The windlass（锚机）is the usual anchor handling device where one machine may be used to handle both anchor.,A more recent development,particularly on large vessels,is the split windlass where one machine is used for each anchor.,One unit of a split windlass(分离式锚机）is shown in Fig.25-1.,The rotating units consist of a cable lifter(锚链轮）with shaped smug（凸起）to grip the anchor cable（锚链）,a mooring drum（绞缆筒）for paying out（放松）or letting go（放出）of mooring wires and a warp end for warping duties.,Each of these units maybe separately engaged（啮合）or disengaged by means or a dog clutch（牙嵌离合器）,although the warp end is often driven in association with the mooring drum.,A spur gear（正齿轮）assembly transmits the motor drive to shaft where the various dog clutches enable the power take-off.,Separate band brakes（独立式刹车）are fitted hold the cable lifter and the mooring drum（绞缆筒）when the power is switched off.,The cable lifter unit（锚链轮）,show in Fig.25-1,is mounted so as to raise and lower the cable from the spurling pipe（锚链管）,which is at the top and center of the chain or cable locker（锚链舱）.,Details of the snugs（卡块）used to grip the cable and band brake（带式刹车）can be seen.,Anchor capstans（起锚绞盘）are used in some installations where the cable lifter rotates about a vertical axis.,Only the cable lifter unit is located on deck,the driving machinery（驱动机械）being on the deck below.,A warping end or barrel may be driven by the same unit and is positioned near the cable lifter.,The efficient working of the anchor windlass is essential to the safety of the ship.An anchor windlass can expect to fulfill（满足）the following:,1.The windlass cable lifter brakes must be able to control the running anchor and cable when the cable lifter is disconnected from the gear during“letting go”（放锚）.,Average cable speeds vary between 5-7 m/sec during this operation,2.The windlass must be able heave a certain weight of cable at a specified speed（额定转速）.,This“full load”duty of the windlass varies but is commonly between 4 and 6 times the weight of one anchor,the speed of haul being at least 9 m/min up to 15 m/min.,3.The braking effort（刹车效果）obtained at the cable lifter must be at least equal to 40 percent of the breaking strength of the cable.,Most anchor handing equipments incorporate（包含）warp ends for mooring purposes（系泊）and line speeds of up to 0.75 to 1.00 m/sec are required.,The most conventional types of equipment in use are as follows.,Windlasses,This equipment is self-contained（独立的）and normally one prime mover drives two cablelifters and two warp ends（绞缆端）,the latter may not be declutchable（离合装置）and,if so,rotate when the cablelifters are engaged.,There is some variation in detail design of cable lifters and in their drives.,Due to the low speed of rotation required of the cablelifter whilst heaving anchor,(345r/min)a high gear reduction(齿轮减速机构）is needed when the windlass is driven by a high speed electric of hydraulic motor.,This is generally obtained by using a high ratio worm gear（涡轮）followed by a single step of spur gears（单级正齿轮）between the warpend shaft and cablelifters.,Alternatively,multi steps of spur gears are used.,Capstans（起锚机）with this type of equipment the driving machinery is situated below deck and the cablelifters are mounted horizontally being driven by vertical shafts.,Mooring winches,Mooring winches provide the facility for tensioning the wire up to the stalling capacity（堵转转矩）of the winch（绞车）,usually 1.5 times full load（全负荷）,thereafter the load is held（握持）by the prime mover brake or barrel brake when the power is shut off.,The winch cannot pay out wire unless the brake is overhauled（超越）or recover wire unless manually operated,thus wires may become slack.,The majority of automatic mooring winches（自动系缆机）are spur geared（正齿轮）to improve the backward efficiency of the gear train for rendering,the gearing（齿轮机构）and bearings being totally enclosed and lubricated from the oil sump.,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.,Worm geared（涡轮蜗杆）automatic mooring winches are uncommon,as the multistart（多次起动）feature required to improve gear efficiency reduces the main advantage of the worm gear i.e the high gear ratio（传动比较高）.,Winches with various arrangements of barrels are the usual mooring equipment used on board ships.,A mooring winch is Fig.25-2 where the various parts can be identified.,The winch barrel or drum is used for hauling（收紧）in or letting out the wires or ropes which will fasten the ship to the shore.,The warp end is used when moving the ship using ropes or wires fastened to bollards（系缆桩）ashore and wrap around the warpend of tile winch.,The construction of a mooring winch will now be examined,again with respect to Fig.25-2.,The motor drive is passed through a spur gear transmission（直齿轮传动机构）,a clutch and thus to the drum（卷筒）and warp end.,A substantial（坚实的）frame supports the assembly and a band brake is used to hold the drum when required.,The control arrangements for the drive motor permit forward or reverse rotation together with a selection of speeds during operation.,Modern mooring winches are arranged as automatic self tensioning units（自动张紧装置）.,The flow of the tides（潮）or changes in draught（吃水）due to cargo operations may result in tensioning or slackening of mooring wires.,To avid constant attention to the mooring wires the automatic self tensioning arrangement provides for paying out(releasing)or recovering wire when a pre-set tension is not present.,