Lesson 19　Cargo handling equipment 轮机英语课件.ppt

Lesson 19 Cargo handling equipment (货物装卸设备) The various items of machinery and equipment can be found outside of the machinery space. These include deck machinery such as mooring equipment(系缆设备), anchor handling equipment(抛锚设备), cargo handling equipment and hatch covers(舱口盖). Other items include lifeboats(救生艇) and liferafts(救生筏), emergency equipment, watertight doors, valve actuator, stabilizers(减摇装置) and bow thrusters(船头推进器). The cargo handling equipment will now be described. Cargo winches are used with various derrick(吊杆) systems arranged for cargo handling. The unit is rated according to the safe working load to be lifted and usually has a double speed provision(装置) when working at half load. In the cargo winch, spur reduction gearing transfers the motor drive to the barrel shaft. A warp end(卷绕端) may be fitted for operating the derrick topping lift (顶牵索) (the wire which adjusts the derrick height). Manually operated band brakes may be fitted and the drive motor will have a brake arranged to fail-safe(故障保护), i.e. it will hold the load if power fails or the machine is stopped. A derrick rig(装置) is known as ‘union purchase’(双杆联吊装置). One derrick is positioned over the quayside and the other almost vertically over the hold(货舱). Topping wires fix the height of the derricks and stays(稳索) to the deck may be used to prevent fore and aft movement. Cargo handling wires run from two winches and join at the hook. A combination of movements from two winches enables lifting, transferring and lowering of the cargo. Cranes have replaced derricks on many modern ships. 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. Various types of crane exist for particular duties. In a general cargo crane, three separate drives provide the principal movements: a hoisting(起升) motor for lifting the load, a luffing(变幅) motor for raising or lowering the jib