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ulley, 11" diameter for two 1"belts

m

show the bevel wheels and a footstep bearing for the governor spindle. In the design of the footstep bearing, means for adjusting the height of the spindle are required.

Draw a plan projected from M.

In view L draw, in outside elevation, the pulley and footstep bearing only and omit all else.

Scale, .

Draw also, full size, the profile of the larger end of one of the teeth of the larger bevel wheel, taking for the rolling or describing circle for the cycloidal curves a diameter equal to twice the pitch. (140.) Note.-Dotted lines representing hidden parts are not required to be drawn ; nor should the figured dimensions be inserted.

Questions, only three to be answered.

The sketches in answer to these questions should be drawn freehand. (g) Point out on sketches the portions of the surface of the

governor stand, Diagram Y, which should be machined, and describe how the machining should be done. Why are two belts employed to drive the governor instead of one? (20.) (h) Give sketches showing the methods of constructing the ends of wrought-iron or steel pipes to facilitate their

connection.

(20.) (k) The longitudinal bar stays of a short boiler are pitched at a distance from one another of 16", both horizontally and vertically. If the working pressure in the boiler is 135 lbs. per square inch by gauge, determine the diameter of the stays when made of mild steel. Show by sketches how the ends of the stays are formed and firmly secured to the flat end-plates of the boiler. (20.) (1) Explain how, by the use of bell-cranks, a reciprocating motion may be modified in direction and amplitude, and the force to be transmitted arranged to be either a pull or a thrust, as desired. Illustrate your answer by describing with sketches a sufficient portion of the gear whereby the points at the junction of two lines of rails on a railway may be actuated from the interior of the signal-box. (20.) (m) Explain how a considerable mechanical advantage, whereby a small force may be enabled to overcome a great resistance, can be derived from the use of a worm and wormwheel. Suppose the worm-wheel to have 120 teeth and the resistance to its rotation to be exerted at a radius of 2', and also suppose the effort to be applied to the worm shaft at a radius of 9", the worm being single-threaded,

what will be approximately the ratio of the resisting to the urging force, taking account of friction? Quote an example of the use of this form of gear, and state what provision is necessary to prevent the worm from being displaced relatively to the shaft when it is made in a separate piece. (20.) (n) Sketch and describe the construction of a mushroom valve as used in a gas engine, and show also the cam mechanism for driving it. State the purpose of the valve you select for description. (20.)

Honours Examination.

INSTRUCTIONS.

Read the General Instructions on page 1.

You are permitted to answer only eight of the following questions.

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 was formerly worked at home by candidates for Honours in this subject has been 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.

51. It is required to employ water-pressure to effect the sliding motion of a piece

(a) against a resistance which acts one way only;

() against a resistance which acts with equal force each way alternately;

(c) against a resistance which acts with less force one way than the other;

() against a resistance which acts one way only, but which is sometimes considerably greater than at other times.

Give sketches and descriptions of the constructions

suitable for each of these cases, and refer to an instance of the employment of each. (50.) 52. Quote an instance of the automatic regulation of the urging force of high pressure fluid by valves for each of the following purposes :-In (1) it is required to maintain a continuous motion of the machine; in (2) a definite movement, to an extent which may be varied, is required to be effected in either of two opposite directions, and the movement to automatically cease until again wanted. With the aid of sketches, describe the necessary constructions. (50.) 53. Give sketches, with figured dimensions, of a joint suitable for connecting two lengths of cast-iron pipe of 41" internal diameter, which is required to convey water under a hydrostatic pressure of 800 lbs. per square inch. Explain how you arrive at those dimensions which you calculate. (50.) 54. Sketch and describe the construction of a bearing to support a horizontal rotating shaft in which adjustments for wear are provided in two directions transverse to the shaft. Quote instances, and give some particulars, of examples in which such a form of construction has been, or might be, used with advantage.

(50.)

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55. Describe, with sketches, how a hook-bolt,. shown in Fig. 1, would be used. Suppose the section of the shank of the bolt to be a rectangle axd, and the line of action of the force exerted on the hooked head to be as shown in Fig. 1, determine the ratio of the greatest stress on the shank to the mean stress on the serewed portion of the bolt at the bottom of the thread in terms of a and d, and determine the ratio of a to d for uniformity of strength. What proportion of a to d is ordinarily adopted, and what is the consequent ratio of the stresses ?

(50.)

56. Two lengths of shafting are connected by a flanged coupling, as shown in Fig. 2, in which a sleeve, the internal

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diameter of which is equal to the diameter of the bolt circle, wraps both flanges, the bolt holes being formed half in the flanges and half in the sleeve. Determine the diameter of each of 10 coupling bolts which will give to the coupling the same strength as a solid shaft of 14" diameter, the diameter of the bolt circle being 17", and the thickness of each flange 31", the material of the bolts being of the same strength as that of the shaft.

(50.) 57. With the aid of sketches, describe the construction of the apparatus necessary for testing the shearing strength of a specimen of steel, and explain how the resistance to shearing depends on the way in which the specimen is held.

Point out the character and cause of the relation which holds between the proof shearing and the proof tensile stress. (50.) 58. Describe how you would put together the steel plates to form the cylindrical shell of a marine boiler of 12' diameter and 8' 6' long. Estimate the thickness of plate you would use for a working pressure of steam of 110 lbs. per square inch. Give sketches of a ring joint and a longitudinal joint, with figured dimensions, and calculate the efficiency of the longitudinal joint.

(50.)

59. Give sketches with figured dimensions showing the details of the construction of a Galloway tube and also a Field tube, and show, also, how they are fitted to a steam boiler. Point out the merits of each.

(50.)

60. Give sketches showing the construction of a liquid-fuel injector, and describe how it is used. Show also the

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