Lesson 18 Steering Gear1. Main Contents of the Text 2. Useful Vocabulary & Special Terms 3. Detailed Analysis of Difficult Sentences 4. Review Questions 5. Some Relevant Multiple Choice ExercisesMain Contents of the TextoThe importance and functions of steering gear oFour main types of steering gear employed for power operation of the rudder, including the two-ram and four-ram hydraulic steering gearoThree types of steering gear according to the way the steering gear is operatedoThe control equipment of steering gearoElectrical controloSteering gear testing舵的作用：船舶的操纵性，是船舶的主要 航行性能之一。舵是船舶操纵装 置的一个重要部件。舵是一块平板或具有流线型截 面的板，称为舵叶(rudder)。 装在船尾中纵剖面或对称于中纵 剖面的位置上。它垂直地浸没在 水中，并能绕舵轴转动。 舵(steering gear)是船舶的一种十分重要和不 可缺少的专用设备。可以想象，如果船没有舵，或 舵失灵，就象汽车没有方向盘一样，将无法行驶） 在大海里任凭风浪摆布。无主动航向的船不仅不能 保证航行的安全，而且是不能到达目的港的。船舵主要由舵叶(rudder)和舵杆(rudder stock) 组成，舵叶是产生水压力的部分，舵杆的作用是转动 舵叶和保证舵叶具有足够的强度）舵的作用原理是当 水流以某冲角冲至舵叶上时，便产生了流体动力，此 作用力通过舵杆传递并船体上，从而迫使船舶转向， 也就达到了调整航向的目的。 液压舵机组成框图液压舵机组成框图变向泵式换向阀式反馈机构发 送 器受 动 器变向变量泵转舵机构舵 叶远操机构操 纵 阀三位四通阀控制油缸式换向阀 手、液动转舵机构舵 叶副油泵主油泵一、泵控型液压舵机一、泵控型液压舵机受动器反馈机构变向泵转舵机构舵柱储能弹簧防浪阀Useful Vocabulary & Special Termso1.Accomplish : succeed in doing something, achieve 完成，实现o2.Situate: be situated= to be in a particular position 位于o3.Swivel: to turn something around that is fixed to a central point旋转Useful Vocabulary & Special Termso1.swivel blocko2. the steering wheel console o3. a flexible couplingo4.slipper ringo5.swash plateo6. to control the ships course o7.the electro-hydraulic gear o8. the pump operating rod o9. the standby steering mechanism o10.hunting gearDetailed Analysis of Difficult Sentenceso1.the types of steering gear employed for power operation of the rudder:o(i) the steam steering gear, 蒸汽舵机o(ii) the hydraulic steering gear,液压舵机o(iii) the electric steering gear and 电动舵机o(iv) the electro-hydraulic steering gear.电液 舵机2.The types of steering gear according to the ways of the steering gear is operated:o1. steam steering gearo2. the hand steering gearo3. automatic steering gear3. The total system may be considered made up of three parts: control equipment, a power unit and a transmission to the rudder stock(舵杆).(转舵机构)控制设备、动力单元（动力机构）、转舵机构RudderRudder stockTransmission unitPowerunitControlequipmentTilleroA two ram(撞杆) hydraulic gear consists of a hydraulic ram situated on the port side of the tiller(舵柄) and another ram on the starboard side,o双撞杆液压操舵装置是由位于舵柄左侧的液 压撞杆和位于舵柄右侧的另一撞杆组成.olinked at their outer ends to the tiller arm by a crosshead and swivel block(转动滑块), Rudder stockTiller arm RamHunting gearCrosshead & swivel blockControl rodCrosshead & swivel blockothe other ends of the rams working inside their own hydraulic cylinders and pipes connect these cylinders to a hydraulic pump. oA four-ram hydraulic steering gear may be fitted in large ships for greater steering power, instead of the two-ram type. oIt is simply a double two-ram unit, so that the force of two diagonally opposite rams can act on the tiller to produce double the turning effect.oThe pump control is moved by the telemotor(液压传动操舵装置) through a floating lever. oThe hunting gear returns the pump operating rod to mid position as soon as the helmsman(舵手) stops turning the wheel. oWhen the rudder has moved through the angle corresponding to the wheel position, it will remain there until the wheel and telemotor are moved. oIf the pressure in the system rises to about 10 per cent above normal, double spring-loaded relief valves allow the tiller to give way slightly by by-passing a little of the oil into the other cylinder. oIt comprises a transmitter(发送 器), a receiver, pipes and a charging unit(充电装置). oThe transmitter, which is built into the steering wheel console (舵轮控制台), is located on the bridge and the receiver is mounted on the steering gear. oA cut-off lever connected to the moving tiller will bring the floating lever pivot and the lever into line at right angles to the screw shaft axis. o与移动舵柄相连的反馈杆带动浮动杆的铰接 点及浮动杆与螺纹杆轴线成一合适角度.oThis control spindle operates the slipper ring or swash plate(倾 斜盘) of the variable delivery pump, which controls the suction and discharge of the oil.The basic structure of steering gearoPlease refer to the drawing on the screen and read paragraphs on page124 to page125:Review Questions o1.Whats the main function of the steering gear on board?o2. There are four main types of steering gears on board, what are they?o3 What are the three parts of the whole steering gear system? And what are their functions?o4.What is the working principle of electro-hydraulic gear？o5. What may be fitted in large ships for greater steering power, a four-ram hydraulic steering gear or the two-ram type?o6.If a heavy sea strikes the rudder, what will happen?o7.Whats the difference between a four-ram hydraulic steering gear and the two-ram steering gear?o8.Whats the function of double spring-loaded relief valves?o9.How does the telemotor control works?