Name: ……………………………………………………………………..…..…… ID. : …………………………..

Major: ………………………………………... Page 1/15

Prince of Songkla University

Faculty of Engineering

Final Examination Semester 2 Academic Year : 2002

Date : 21 February 2002 Time : 13.30-16.30

Subject : 226-305 Machine Design I Room : R300

Instruction

1.  There are 5 questions , 200 marks.

2.  Attempt to do all questions in test paper. If it isn’t enough , you can use other blank pages.

3.  Books, sheets of paper note ,a dictionary and a calculator are allowed.

4.  Don’t write in red pen.

No. / Full Score / Marks
1 / 34
2 / 65
3 / 26
4 / 38
5 / 37
Total / 200
Mr. Pichet Trakarnchaisiri

Lecturer

1.  The block-type hand break shown in the figure has a face width of 30 mm. and a mean coefficient of friction of 0.25. For an estimated actuating force of 400 N. (34 marks)

Determine

1.1  Find q1 ,q2 ,qa of hand brake. ( 8 marks)

1.2  The maximum pressure on the shoe. (20 marks)

1.3  The breaking torque. ( 6 marks)

(Dimension in figure ; millimeters)

2.  The figure is a schematic drawing of a countershaft that supports two V-belt pulleys. The countershaft runs with constant torque at 1200 rev/min. The belt tension on the loose side of pulley B is 15 percent of the tension on tight side of pulley A. (65 marks)

Given : AISI 1030 cold rolled shaft is constant size with Se = 135 MPa

2.1  Draw Loading Diagram and Moment Diagram of this counter shaft. (35 marks)

2.2  Find the bearing reactions at O and E due to the belt pulls; assume the belt pulleys are parallel and neglect the weight effect of shaft and pulleys. (20 marks)

2.3  Find the least diameter at 1.5 of safety factor ; avoid yielding failure at critical point on shaft. (10 marks)

(Distance & diameters in figure; millimeters)

3.  Find the maximum stress and safety factor in the weld metal of the bracket shown in the figure when joint is welded by AWS electrode standard E3013. (26 marks)

4.  A 60-hp four-cylinder internal combustion engine is used to drive textile machinery under a schedule of two shifts per day (8 working hours per shift). The drive consists of two 26-in sheaves, maximum spaced about 12 ft apart, with a sheave speed of 400 rev/min. Select V-belt(s) arrangement to handle this job. (38 marks)

4.1  The design power and type of V-belt(s) (6 marks)

4.2  Check all parameters of setting V-belt to be consistent with the condition of design. If not,select new center distance. (7 marks)

4.3  Determine the standard pitch length and true center distance. (14 marks)

4.4  The amount of V-belt(s) used in transmitting power. (11 marks)

5.  A 720 rev/min 45-hp squirrel-cage motor is to drive a two-cylinder reciprocating pump

with some impact which is to be located out-of-doors under a shed. The pump is to run at full load for 24 hr/day, and freedom from breakdowns is especially desired. The pump speed is 144 rev/min. (37 marks)

5.1  Select suitable chain and sprocket sizes of driver and driven. (23 marks)

5.2  Select the center distance of standard chains. (14 marks)