M. Ibbotson - Professional english in use engineering (794233), страница 4
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A flat surface may be vertical,or inclined (sloping at an angle to the horizontal or vertical plane).Faces that are vertical, such as those of the walls of buildings, are described by engineers asbeing plumb. Structures that are slightly inclined from vertical are said to be out of plumb.14Professional English in Use Engineering4.1Complete the key dimensions of the Millau Viaduct in France, using the words in the box.Look at A opposite to help you.I heightoverallthicknessspanwidth(1) ................................ length: 2,460 m(2) Maximum ................................
between supports: 342m(3) ................................ of tallest support (ground to deck): 245m(4) ................................ of deck: 32m(5) ................................ of deck: 4.2 m4.2Decide whether the sentences about the viaduct are true or false, and correct the falsesentences. Look at A and B opposite to help you.1 The height of the towers is measured horizontally.2 The overall span is measured along the width of the bridge.3 The tops of the towers are at different levels, so a horizontal plane striking the top of onetower will not strike the tops of all the others.4 The highest point of the structure is the top extremity of the highest tower.5 The thickness of each tower decreases towards the top, so the faces of the towers areplumb.6 The greatest thickness of each tower is its internal thickness at its base.4.3Circle the correct words to complete the text about extra-high voltage (EHV) power lines.Look at A and B opposite to help you.
The first one has been done for you.On EHV transmission lines, cables- called conductors- (1) incline /~between pylons, whichare described as supports. The conductors are suspended from the supports by rods, calledinsulators. On straight sections of line, the insulators are (2) level 1 plumb, hanging verticallyfrom the supports.
At supports where the direction of the line changes, pairs of insulators areused. In this situation, the insulators are (3) inclined j striking from the vertical plane, as theyare pulled (4) plumb 1 out of plumb by the conductors pulling in different directions.The higher the voltage being transmitted by the line, the greater the required distance betweenthe conductor and the support, in order to provide effective insulation.
The (5) length I widthof insulators therefore varies, depending on the voltage. Higher voltages also mean thatconductors must be located at a greater minimum (6) height 1 thickness above the ground, forsafety. This distance is measured between the ground and the lowest point of the cable.4.4 Read the text below. Can you answer the questions?On long suspension bridges, when the distance between the vertical centres of the towersat either side of the bridge is measured horizontally, the distance between the tops of thetwo towers will be several millimetres longer than the distance between their bases.
Doesthis mean the towers are out of plumb? Why is there a difference?Ov~r .f-otjOll~Think of a product with a fairly simple shape. What dimensions would need to be specifiedon a drawing in order to allow the product to be manufactured?Professional English in Use EngineeringISlocating and setting out-Centrelines and offsetsThe drawing below shows the position of some holes for bolts. The distances betweenthe holes can be shown as running dimensions or as chain dimensions. In both cases, thecentreline (CL)- a line through the centre of the hole- is marked (drawn), and the distancesbetween the centrelines are given. Distances between centrelines are called centre-to-centre(c/c) dimensions.
The holes below are at 100 mm centres.-$ -$ -$ -$II~I·I·I100100~I.1..I200100·IRunning dimensions.IChain dimensions300100. I.100 mm c/cA written noteCentrelines are often used as reference points. These can be measured from, in order to locate-that is, give the position of- points on components. The measurements are offset from thecentreline - each is at a certain distance from it, and the offsets are measured at a right-angleto the centreline (at 90 degrees to it).Note: We can say at a right-angle to X, at 90 degrees to X, or at right-angles to X.-GridsIn large designs, notably those of structures, grids are used for horizontal positioning.
Thegridlines have numbers and letters. All numbered gridlines are parallel with one anotherthat is, they are straight, and are regular distances apart. Lettered lines also run parallel withone another, and are perpendicular to (at a right-angle to) the numbered lines.The plan below shows part of the floor of an office building. The perpendicular gridlinesintersect at (cross at) the centres of columns. An opening (hole) in the floor is shown usingcoordinate dimensions.
These allow the site engineer to set out (mark the position of) theopening by squaring off the gridlines- marking lines that run at a right-angle to them- andthen measuring along these lines using a tape measure.A theodolite- an optical device used for measuring angles- can be used to square offgridlines accurately. To double-check dimensions- that is, carry out an extra checkdiagonal measurements can be used, as in the engineer's sketch below. The length ofdiagonals can be calculated using Pythagoras's Theorem.G- ill--:2~[- ----------$ ----------- -----·$ 00LO,......~H-~Diii!!!II•1920 I 980, iiiIiI-$ --- --- - 8 -_5_0_4_0____.i15040.'2Drawing16Professional English in Use Engineering---$ '3Site engineer's sketch5.1Look at the sentences about the design of a ship. Replace the underlined words andexpressions with alternative words and expressions from A opposite.1 The handrail is fixed by 115 brackets, which are 175 mm apart, between their centres.2 The dimensions are measured from the line down the middle of the ship.How far is the widest point of the ship located away from the centreline?34 Are the adjacent lengths of handrail at 90 degrees to each other?5 These dimensions allow you to establish the position of the hole.5.2Look at the extracts from technical discussions on a construction site.
Complete the sentencesusing the words in the box. Look at B opposite to help you.grid lineintersectparallelperpendicularset outsquare offAc.cocding -to -this dfa.wing, ................................ 8 funs along -the. ex-tefr)(l.l wall of -the. s-tfuC:tO(e.2lhe. posHions wefe maf\(.ed ac.cufa-tel'::l -3ihe.'::l wefe ................................ b'::l ouf si-te engir>e.ef.lhe.
ex-tef nal wall funs along gfidline \, and -the. ln-tefnal c.ocfidOf wallf uns along gfidline 2, so -the. walls ace ................................ wi-th each oihe.f .4I '11e ma(\(.ed a Cfoss on -the. concfe-te flooc, showing whefe -the. -two gfidlines ................................ .5We need -to show -the. posHion of -the. COfr>e.f of -the. s-taifcase wi-th COOfdina-tedimensions.
lhe.fe should be -two ................................ dimensions, -ta((.en fcom -two gndlines .65.3We '11 use -the. -theodoli-te -to ................................ -the. gndline and mac((. a nine.-t'::l-degfee offse-t.Match the two parts of the sentences to complete the extract from a training manual.Look at A and B opposite to help you.In civil engineeri ng, the following precautions can help to prevent costly setting-out mistakes.(1)(2)(3)(4)Always use a steel tape measure (never a plast ic one)Check that both diagonals of rectangular shapes are equalMeasure dimensions in two directions, from parallel gridlines,Add up cha in dimensions to give ru nning dimensionsato check that corners are right-angles.cto prevent slight errors being multiplied.bto ensure it does not stretch under tension .dto double-check you r measu rements.Ove,r .f-o 1:fou~Choose a nearby object, or part of a building.
Describe it, using language from A and Bopposite. (You could also give approximate measurements.) Then imagine you are designingthe object or the part of the building. What dimensions and lines will be needed on thedrawings in order to locate its features?Professional English in Use Engineering17Dimensions of circles-Key dimensions of circlesAn engineer is giving a training course to a group of technical sales staff who work for a tyremanufacturer. During the talk, she mentions a number of dimensions relating to circles.'Obviously, the outside edge of a tyre forms acircle, as you can see in this simple diagram. Theouter circle in the diagram is the outside of thetyre, and the inner circle - the circle with thesmaller diameter - represents both the insideof the tyre and the outside of the wheel.
And,clearly, the inner circle is right in the middle ofthe outer circle - it's exactly in the centre. Sobecause it's central, that means the inside andoutside of the tyre form concentric circles. Andas the tyre is circular, simple geometry tells usthat measurements of the radius, taken from thecentre of the circle to different points on its edge-points on the circumference- are equal. Allthe radii are the same. In other words, the tyrehas a constant radius.''But when a tyre is fitted to a vehicle, it'scompressed against the road surface. Thatmeans its geometry changes. So while the wheel- the inner circle - obviously remains round,the circumference of the tyre - the outer circle changes shape.
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