2. Describe the advantages and disadvantages of the hydraulic system of working lifts, cranes and similar machinery from a central power station. Illustrate your remarks with reference to the Sydney Hydraulic Power Company, giving particulars of their power plant. 3. Explain fully, and illustrate by sketches where necessary, how you would design a modern undershot water-wheel, giving full particulars of the speed of the wheel, form of buckets, and probable efficiency. Show how to determine the form of the guides and wheel vanes in an impulse turbine, assuming all necessary data. B. 4. Contrast the functions of the flywheel and the governor in an engine. Explain precisely how you would determine the dimensions of a steam engine flywheel for a given fluctuation of speed. Would you adopt the same method for a gas engine flywheel? 5. Make neat sketches (plan and sections) of an ordinary slide valve and valve seat. Explain clearly, with the aid of a diagram, why, with such a valve, it is not possible to obtain a symmetrical distribution of steam between the two ends of the cylinder. The travel of a slide valve is 6 inches, outside lap 1 inch. Find in feet per second the velocity with which the port commences to open when the revolutions are 70 per minute. 6. Describe one of the following tests, giving a description of the apparatus used, formulæ, and approximate results(a) Determination of efficiency of a Pelton wheel. (b) Determination of Young's modulus for cast-iron by bending; also work out E for a Monier beam 14 in. x 14 in., which deflected inch under a central load of 10 tons, the supports being 5 ft. 6 in. apart. C. 7. The last ten miles of a mineral railway connecting a mining centre to the main trunk line would pass through a hilly district having a formation which chiefly consists of rock. What considerations would influence you in deciding the ruling grade, curve of minimum radius, distribution of rise and fall, type of locomotive and rollingstock, permanent way, embankments, cuttings, bridges and culverts? 8. Describe, by means of sketches, the method of setting out a tunnel, and the process of sinking the shafts and driving the headings in heavy ground. Show all necessary timbering, and write on the dimensions. 9. How would you calculate the probable area required for a culvert under a railway embankment? What data would you require? How would you determine the total quantity of water that might reasonably be expected for a water supply from a given catchment area, assuming all necessary data? APPLIED MECHANICS III. (The drawings to be made on cartridge paper. All necessary dimensions are to be shown, and parts in section hatched.) Only ONE question to be attempted. Students taking Honours MUST attempt question No. 1. 1. Design a piston valve and liner having given the following conditions and data Steam to be taken on the inside. Exhaust steam to pass through the body of the valve, and The necessary valve and piston diagram is to be drawn. Sufficient views to shew all dimensions of ports, pipes, passages, etc., are to be given. The drawing to be to a scale of full size. Data Steam press, 185 lb. square inch. Diameter of cylinder, 8 inches. Revolutions per minute, 500. Cut off (mean), 65. Lead-Top, 1 inch; bottom, inch. 2. Design a 4-inch gunmetal right angle stop valve, suitable for a steam pressure of 160 lb. per square inch. The drawing to be to a scale of full size. 3. Design the piston rod crosshead, shoe and guides to suit the following engine, shewing all necessary fixings to columns, dimensions, etc. The drawing to be to a scale of full size. Data Engine of vertical type, fitted with reversing gear, the cylinder being carried by 4 steel columns 1 inch diameter. Steam pressure, 185 lb. per square inch. Back pressure, 30 lb. per square inch. Stroke, 9 inches. Revolutions per minute, 500. Cut off (mean), 65. Connecting rod centres, 1 foot 8 inches. Centre to centre of columns in a line parallel to axis of Diameter of gudgeon, 24 inches. NOTE. The strength of steel studs and bolts may be taken as follows 012340 7 38.48 39.87 41.28 50-26 51-84 53.45 55.08 56.74 58.42 60.13 61.86 63.61 65.39 67.20 69.02 70-88 72-75 74.66 76.58 78.54 80.51 82-51 84-54 86.59 88-66 90.76 92.88 RAILWAY ENGINEERING-(CIVIL). 1. Explain the meaning of the terms-Curve Resistance, Grade Resistance, Train Resistance, and show how to calculate the amount in each case. Explain also how the amount of rise and fall affects the cost of working a railway. What do you understand by the term Virtual Profile? 2. A train consisting of one engine and tender, 20 trucks fully loaded, and one van, weighing in all 300 tons; 60 per cent. of this is braked. If the train is moving at 40 miles an hour when the brakes are applied on a down grade of 1 in 40, and the efficiency of the brakes is 15 per cent., how far will the train travel before coming to rest? Describe briefly the Westinghouse Brake. 3. Compare the cost of working two lines of railway, each 20 miles long, one on a level throughout, the other rising and falling 1000 feet, having given the following data Total weight of engine and train, 400 tons. Mean speed over the 20 miles, 18 miles an hour. Cost of water, 10 per cent. that of the coal. 4. Write an Essay on the area of Railway Culverts and Bridges to discharge flood water. Write down the various formula which have been proposed, and explain fully their limitations and the manner in which you would employ them in a few typical cases. 5. Explain the terms-Boiler Power, Cylinder Power, and Tractive Force, as applied to the locomotive. What are the chief sources of loss of efficiency in the locomotive? A Locomotive Engine has two cylinders 18 inches in diameter and 24 inches stroke and driving wheels 4 feet in diameter. What is the maximum load it will haul up an incline of 1 in 40 at a speed of 10 miles an hour, if the mean steam pressure in the cylinders is 100 lb. per square inch? What should be the total load on the driving wheels of such an engine? 6. Write an Essay on one of the following subjects (a) The Balancing of Locomotive Engines. (b) The Advantages and Disadvantages of the Compound Locomotive Engine compared with the ordinary simple Engine, giving particulars of the most important types of Compound Locomotives at present in use. |