Second Stage or Advanced Examination. INSTRUCTIONS. Read the General Instructions on page 1. Answer briefly any three, but not more than three, of the following questions, and draw the example given. The example should be drawn on the side of the paper on which the candidate's number is printed. Foolscap paper must not be used for this stage. Questions. The sketches in answer to these questions should be drawn freehand. (g.) With the aid of sketches describe how to make a steamtight joint between two flanges. What are the considerations which should guide you in determining the most suitable diameter and number of bolts to use? (h.) Mention some instances in which, whilst relative motion of two pieces of a machine is required to take place, the leakage of high pressure steam or water between the surfaces which are in moving contact is required to be prevented, (a) when the relative motion is turning, (b) sliding. Sketch and describe one suitable form of construction for each of these two motions, selecting two methods which differ from each other. (20.) (k.) Explain why the rigid fixing of the ends strengthens a column which is required to sustain a compressive load. Make sketches showing how the ends of a wrought-iron or steel column, which frequently forms a part of the frame of an engine or other machine, are secured to the castings. (20.) (1.) The two lengths of a tie rod of 1" round iron are connected by a sleeve and two steel cotters, the rod ends at the junction being enlarged to maintain uniformity of strength; give sketches of the joint with figured dimensions. (20.) (m.) Sketch and describe the construction of one form of thrust bearing, showing how it is automatically lubricated. (20.) (n.) Describe how the parts of the bearing shown on diagram Y are put together when the crank shaft is in place, and explain how adjustment is made for wear. State what advantage results from fitting the cap to the outside of the snugs. How would you connect the bolts for securing the cap to the frame if you were unable to insert them from below? (20.) Example to be Drawn. Crank shaft bearing for horizontal engine. Two views, L and M, are given. View M is not to be drawn. Draw view L so as to show the part to the left of the centre in section, as in the diagram, and the part to the right in outside elevation and not in section. Draw also an elevation as seen when looking in the direction of the arrow, the left half showing a section through the centre of the bearing, and the right half an outside view showing the end of the frame. Scaleths. (140.) NOTE.-Dotted lines representing hidden parts are not required to be drawn, and will receive no credit. Honours Examination. INSTRUCTIONS. Read the General Instructions on page 1. You are permitted to answer only eight of the following questions. The same number of marks is allotted to each question. The sketches and answers to these questions may be drawn and written on foolscap paper, which may be obtained on application to the superintendents of the examination. The sketches may be in pencil, and need not be drawn to scale, but should be neat and in good proportion. The written answers should be in ink, and must adjoin the sketches to which they refer. NOTE FOR CANDIDATES IN HONOURS. The paper which has hitherto been worked at home by candidates for Honours in this subject is discontinued, and an examination at South Kensington substituted for it. This examination will only be open to candidates who answer the present paper sufficiently well to give them a reasonable chance, if the South Kensington papers are well answered, of obtaining a 1st or 2nd class. Honours candidates admissible to the examination at South Kensington will be so informed in due course. 21. Determine all the important dimensions of a piston-rod for a cylinder of 60" diameter in which the greatest difference of pressure of the steam on the two sides of the piston may be assumed to be 28 lbs. per square inch. The length of the piston-rod is 7' 6". It is made of mild steel, and is secured to the piston by a tapered end and nut, and to the cross-head by a cotter. Make a sketch of the rod (not to scale), inserting figured dimensions. 22. Design and draw a fly-wheel for an engine of 150 horsepower which makes 80 revolutions per minute. The diameter of the engine shaft is 5", and the energy stored in the fly-wheel is required to be 11⁄2 times the energy exerted per revolution. The drawing need not be to scale, but all important dimensions should be inserted. Supposing the greatest fluctuation of energy to be 15 per cent. of the energy exerted in a revolution, what will be the greatest and least velocity of revolution? 23. An overhead travelling crane capable of transporting a load of 30 tons has a span of 32'. The carriage rests equally on two box girders built up of mild steel plates. The depth of each girder at the centre of the span is 30", and the breadth 15". Estimate a suitable thickness of plate and draw a transverse section with figured dimensions showing how the plates are united, and state the diameter and pitch of the rivets you would use. 24. Mention as many varieties of examples as you can of the employment of ball bearings. Give some account of any special machinery and method employed in the manufacture of the spheres, and give sketches and a description of one form of ball bearing. 25. Sketch and describe a centrifugal hydro-extractor, showing the gear by which the high speed of revolution is obtained and the details of the bearings of the revolving vessel. 26. Give a general description with sketches of a hydraulicpassenger lift for an hotel. Assuming a reasonable water pressure and weight and height to be lifted, calculate the diameter of ram necessary. Show details of the construction of the valve and describe how it is worked. 27. Make sketches showing the most suitable form of castiron casing for a centrifugal pump. Suppose the pumpwheel to be 2' 6" diameter, and that 500 cubic feet of water are delivered from it per minute with a tangential velocity of 20' per second, estimate the most suitable. dimensions of the casing and the delivery pipe. 28. Give sketches and a description of a hydraulic ram by means of which a small quantity of pure water may be raised to a considerable height by the descent through a smaller height of a larger quantity of impure water. 29. Describe in detail the process of making a welded joint in a mild steel plate in the construction of a cylindrical or corrugated furnace tube. Show also how the ends of the furnace are secured to the front plate of the boiler and combustion chamber. 30. Give sketches and a description of the details of the construction of the fire-box of a locomotive boiler. Mention the special difficulties in the way of providing a durable construction, and discuss the relative advantages and disadvantages due to the use of copper instead of steel. 31. With the aid of sketches describe the construction of a hydraulic riveting machine, and point out in what particulars the shape and dimensions are designed to enable the machine to be used on the largest possible variety of work. In joining by a machine the plates which compose the shell of a cylindrical boiler, in what order would you rivet the joints? What joints, if any, cannot be machine riveted? 32. Give sketches and descriptions of the methods of constructing couplings for railway carriages, showing one form of automatic coupling. 33. Describe generally the Westinghouse method of stopping a railway train, mentioning the various fittings required. Give details of the design of the air pump, not including the engine which drives the pump. 34. Describe with sketches the construction of a battery of stamps for crushing ore. Give details of the design of the parts most subject to wear, showing how they may be readily replaced. Assume the power to be derived from a water-wheel of 40' diameter, the fall being 30'. Also suppose there are twelve stamps, each weighing 3 cwt., lifted to a height of 15" thirty times a minute. Estimate the horse-power, and the volume of water required per minute, and determine approximately the principal particulars relating to the gearing which should connect the wheel and the stamps. 35. By the aid of sketches describe the construction and the method of use of a machine by means of which the teeth of worm wheels may be machined to accurately fit the worms which gear with them. 36. With the aid of sketches describe the construction of the aftermost bearing which supports the shaft of an overhanging screw propeller. Supposing the aftermost length of shafting to be supported on three equi-distant bearings which are in a straight line and to be joined to the next length by a loose coupling, show that considerable wear in the aftermost bearing may take place without any increase of the maximum bending moment on the shaft, and explain how to determine the extent of deviation of that bearing, from the line of the other two, at which the maximum bending moment will begin to increase. Honours Practical Examination. FIRST PAPER. (Four hours allowed.) A main shaft, running the length of a building, is required to be connected to one of a number of transverse shafts by means of bevel wheels, whose axes are at right angles to one another. You are required to design the bevel wheels, and also a bracket, to be secured to a brick wall, suitable for carrying two pedestals, one for supporting the main shaft, and the other the end of one of the transverse shafts. Adhering to the data given below, draw three views of the wall bracket to a scale of th, showing the pedestals in position without details, but with the principal dimensions figured. The bevel wheels are in the plan required to be drawn in section, and in the other views represented by pitch lines or circles. A development showing the forms of the profiles of the teeth should also be given, set out to a larger scale. Diameter of main shaft.. Diameter of transverse shaft 31" 150 approximately. Distance of axis of main shaft from 21" wall The strength of the wheel teeth must be such as to correspond to the full strength of the transverse shaft, which is of wrought iron, assuming a bending moment on it equal to the twisting moment. Collars to prevent end movement of the transverse shaft are required, but not for the main shaft. The drawings may be finished in pencil, and the section lines drawn freehand. The free use of any note or text book is permitted. SECOND PAPER. (Three hours allowed.) The use of note and text books is prohibited in working this paper. In the accompanying diagram Q is shown two sectional views of a throttle valve for a steam engine. Draw an elevation on a vertical plane at right angles to that of the elevation marked A, and show the right-hand half in section, the section being taken through the axis of the spindle. Draw also, in projection from the above, an outside elevation of the view of which A is the sectional elevation. (1205) B |