PREBOARD EXAMINATION IN MACHINE DESIGN
ANSWER THE FOLLOWING QUESTIONS CORRECTLY AND QUICKLY. SHADE THE LETTER OF
THE BEST ANSWER. CHEATING IS NOT ALLOWED.
1. What is the polar section modulus of a 4-inch solid shaft?
a. A. 25.13 in3 B. 12.57 in4 C. 12.57 in3 D. 25.13 in4
2. A hollow shaft carries a torque 3.4 KN-m at a shearing stress if 55
Mpa. The outside diameter is 1.25 times that of the inside diameter.
Find the inside diameter in mm.
a. A. 64.67 B. 46.67 C. 84.67 D. 74.84
3. It is specified that the angular deformation in a shaft should not
exceed 1” in length of 1.8m. The allowable shearing stress is 53 Mpa.
Determine the diameter of the shaft. The shaft material has G = 77 x
106 Mpa.
a. A. 222.34 mm B. 234.22 mm C. 23.42 cm D. 24.22 cm
4. What modulus of elasticity in tension is required to obtain a unit
deformation of 0.00105 from a load producing a unit stress of 45,000
psi?
a. A. 40 x 106 psi B. 43 x 106 psi C. 45 x 106 psi D. 46 x 106
5. A thrust washer has an inside diameter of 0.5 inch and an outside
diameter of 3 inches. For an allowable bearing pressure of 90 psi, how
much axial load can it sustain?
a. A. 618.5 lb B. 537.2 lb C. 702.2 lb D.
871.2 lb
6. An air cylinder has a bore of 25 mm and is operated with shop air at a
pressure of 90 ps. Find the push force extended by the piston rod in
N.
a. A. 127 B. 70 C. 402 D. 305
7. A line shaft is to transmit 200 Hp at 900 rpm. Find the diameter of
the shaft.
a. A. 2.18 inches B. 2.26 inches C. 3.18 inches D. 3.26 in
8. A main transmitting shaft transmits 350 KW to drive a generator at
2500 rpm, what is the required diameter of the shaft?
a. A. 58.5 mm B. 82.7 mm C. 85.3 mm D. 56.2
mm
9. A round steel shaft rotates at 200 rpm and is subjected to a torque of
275 N-m and a bending moment of 415 N-m. Determine the equivalent
twisting moment.
a. A. 597.84 N-m B. 456.42 N-m C. 546.43 N-m D. 497.85 N-m
10. A 4 inches shaft using a flat key, whose width is 1 inch, is
transmitting a torque of 53,000 in-lb. If the design shearing stress
is 5000 psi, determine the safe length of key.
a. A. 6.3 inches B. 5.3 inches C. 4.3 inches D. 7.0 inches
11. A 75 mm diameter shaft is transmitting 300 KW at 600 rpm. A flange
coupling is used and has 6 bolts, each 18 mm in diameter. Find the
required diameter if the bolt circle based on an average shearing
stress of 27.5 Mpa.
a. A. 227.4 mm B. 477.2 mm C. 274.7 mm D.
247.7 mm
12. A heavy duty shaft coupling is to be secured woth 25 mm bolts at a
distance of 150 mm from the shaft center. The shaft transmits 4330 KW
of power at a speed of 1200 rp,. If the allowable shearing stress for
bolts is 100 Mpa, how many bolts are required?
A. 3 B. 6 C. 5 D. 4
13. A 1.75-inch diameter shaft is supported by two sleeve bearings. The
total load on the wo bearings is 2900 lb. Find the friction power
loss, in Hp, if the coefficient of friction between shaft and bearing
is 0.10 and the shaft rotates 200 rpm.
A. 0.88 Hp B. 0.78 Hp C. 0.98 Hp D. 0.68
, diameter of the collar is 4 inches and the inside diameter is 2
inches.
A. 0.0629 Hp B. 0.0925 Hp C. 0.0269 Hp D. 0.0692 Hp
15. A sleeve bearing has an outside diameter of 38.1 mm and a length of
50.1 mm, the wall thickness is 3/16 inch. The bearing is subjected to
radial load of 450 lb, determine the bearing pressure.
a. A. 100 psi B. 150 psi C. 200 psi D. 250
psi
16. A vertical steel cylinder water tank is 30 m in diameter and 45 m
high. The allowable stress of the steel plate is 120 Mpa. Without
reinforcing angle bars and rods, determine the thickness of the steel
plate.
A. 55.2 mm B. 56.2 mm C. 65.2 mm D. 52.6
mm
17. Determine the bursting steam pressure of a hemispherical steel shell
with a diameter of 100 inches and made of 0.0635 m thick steel plate.
The joint efficiency is 70% and the tensile strength is 60,000 psi.
A. 4020 psi B.4200 psi C. 2500 psi D. 2040
psi
18. A cylinder having an internal diameter of 508 mm and external
diameter of 814.4 mm is subjected to an internal pressure of 69 Mpa
and an external of 14 Mpa. Determine the hoop stress at the inner
surface of the cylinder
A. 90.11 Mpa B. 91.10 Mpa C. 911.0 Mpa D. 19.10 Mpa
19. The root diameter of a double square thread is 0.55 inch. The screw
has a pitch of 0.2 inch. Find the outside diameter and the number of
threads per inch.
A. 0.75 inch and 5 threads/inch C. 0.50 inch and 5
threads/inch
B. 0.75 inch and 4 threads/inch D. 0.50 inch and 4
threads/inch
20. Two shafts 3.6 m between centers carry pulleys 1.2 m in diameter and
0.91 m in diameter respectively, connected by a crossed belt. It is
desired to put the belt on as an open belt. How long a piece must be
cut of it?
A. 300 mm B. 350 mm C. 400 mm D. 250 mm
21. A flat belt is 6 inches wide and 1/3 inch thick and transmits 15 Hp.
The center distance is 8 ft. The driving pulley is 6 inches in
diameter and rotates at 2000 rpm such that the loose side of the belt
is on top. The driven pulley is 18 inches in diameter. The belt
material is 0.035 lb/in3 and the coefficient of friction is 0.30.
Determine the net belt tension.
A. 167.56 lb B. 157.56 lb C. 156.75 lb D. 175.56 lb
22. Two pulleys, 80 cm apart, carry a belt in an open connection. If the
diameter of the pulleys are 40 cm and 15 cm, what is the length of the
belt needed?
A. 248.35 cm B. 348.35 cm C. 265.45 cm D. 305.35 cm
23. A pulley 600 mm in diameter transmits 40 KW at 500 rpm. The arc of
contact between the belt and pulley is 144o , the coefficient of
friction between belt and pulley is 0.35 and the safe working stress
of the belt is 2.1 Mpa. Determine the belt tension ratio, neglecting
the effect of centrifugal force.
A. 2.41 B. 2.14 C. 1.24 D. 4.12
24. A disc clutch has 6 pairs of contacting friction surfaces with an
outside diameter of 200 mm and an inside diameter of 100 mm. The
coefficient of friction of the clutch materials is 0.4 and the axial
force is 1500 N. The shaft speed is 1200 rpm. Find the Hp that can be
transmitted by the clutch assuming uniform pressure.
A. 35.2 Hp B. 23.5 Hp C. 47.2 Hp D. 27.4 Hp
ANSWER THE FOLLOWING QUESTIONS CORRECTLY AND QUICKLY. SHADE THE LETTER OF
THE BEST ANSWER. CHEATING IS NOT ALLOWED.
1. What is the polar section modulus of a 4-inch solid shaft?
a. A. 25.13 in3 B. 12.57 in4 C. 12.57 in3 D. 25.13 in4
2. A hollow shaft carries a torque 3.4 KN-m at a shearing stress if 55
Mpa. The outside diameter is 1.25 times that of the inside diameter.
Find the inside diameter in mm.
a. A. 64.67 B. 46.67 C. 84.67 D. 74.84
3. It is specified that the angular deformation in a shaft should not
exceed 1” in length of 1.8m. The allowable shearing stress is 53 Mpa.
Determine the diameter of the shaft. The shaft material has G = 77 x
106 Mpa.
a. A. 222.34 mm B. 234.22 mm C. 23.42 cm D. 24.22 cm
4. What modulus of elasticity in tension is required to obtain a unit
deformation of 0.00105 from a load producing a unit stress of 45,000
psi?
a. A. 40 x 106 psi B. 43 x 106 psi C. 45 x 106 psi D. 46 x 106
5. A thrust washer has an inside diameter of 0.5 inch and an outside
diameter of 3 inches. For an allowable bearing pressure of 90 psi, how
much axial load can it sustain?
a. A. 618.5 lb B. 537.2 lb C. 702.2 lb D.
871.2 lb
6. An air cylinder has a bore of 25 mm and is operated with shop air at a
pressure of 90 ps. Find the push force extended by the piston rod in
N.
a. A. 127 B. 70 C. 402 D. 305
7. A line shaft is to transmit 200 Hp at 900 rpm. Find the diameter of
the shaft.
a. A. 2.18 inches B. 2.26 inches C. 3.18 inches D. 3.26 in
8. A main transmitting shaft transmits 350 KW to drive a generator at
2500 rpm, what is the required diameter of the shaft?
a. A. 58.5 mm B. 82.7 mm C. 85.3 mm D. 56.2
mm
9. A round steel shaft rotates at 200 rpm and is subjected to a torque of
275 N-m and a bending moment of 415 N-m. Determine the equivalent
twisting moment.
a. A. 597.84 N-m B. 456.42 N-m C. 546.43 N-m D. 497.85 N-m
10. A 4 inches shaft using a flat key, whose width is 1 inch, is
transmitting a torque of 53,000 in-lb. If the design shearing stress
is 5000 psi, determine the safe length of key.
a. A. 6.3 inches B. 5.3 inches C. 4.3 inches D. 7.0 inches
11. A 75 mm diameter shaft is transmitting 300 KW at 600 rpm. A flange
coupling is used and has 6 bolts, each 18 mm in diameter. Find the
required diameter if the bolt circle based on an average shearing
stress of 27.5 Mpa.
a. A. 227.4 mm B. 477.2 mm C. 274.7 mm D.
247.7 mm
12. A heavy duty shaft coupling is to be secured woth 25 mm bolts at a
distance of 150 mm from the shaft center. The shaft transmits 4330 KW
of power at a speed of 1200 rp,. If the allowable shearing stress for
bolts is 100 Mpa, how many bolts are required?
A. 3 B. 6 C. 5 D. 4
13. A 1.75-inch diameter shaft is supported by two sleeve bearings. The
total load on the wo bearings is 2900 lb. Find the friction power
loss, in Hp, if the coefficient of friction between shaft and bearing
is 0.10 and the shaft rotates 200 rpm.
A. 0.88 Hp B. 0.78 Hp C. 0.98 Hp D. 0.68
, diameter of the collar is 4 inches and the inside diameter is 2
inches.
A. 0.0629 Hp B. 0.0925 Hp C. 0.0269 Hp D. 0.0692 Hp
15. A sleeve bearing has an outside diameter of 38.1 mm and a length of
50.1 mm, the wall thickness is 3/16 inch. The bearing is subjected to
radial load of 450 lb, determine the bearing pressure.
a. A. 100 psi B. 150 psi C. 200 psi D. 250
psi
16. A vertical steel cylinder water tank is 30 m in diameter and 45 m
high. The allowable stress of the steel plate is 120 Mpa. Without
reinforcing angle bars and rods, determine the thickness of the steel
plate.
A. 55.2 mm B. 56.2 mm C. 65.2 mm D. 52.6
mm
17. Determine the bursting steam pressure of a hemispherical steel shell
with a diameter of 100 inches and made of 0.0635 m thick steel plate.
The joint efficiency is 70% and the tensile strength is 60,000 psi.
A. 4020 psi B.4200 psi C. 2500 psi D. 2040
psi
18. A cylinder having an internal diameter of 508 mm and external
diameter of 814.4 mm is subjected to an internal pressure of 69 Mpa
and an external of 14 Mpa. Determine the hoop stress at the inner
surface of the cylinder
A. 90.11 Mpa B. 91.10 Mpa C. 911.0 Mpa D. 19.10 Mpa
19. The root diameter of a double square thread is 0.55 inch. The screw
has a pitch of 0.2 inch. Find the outside diameter and the number of
threads per inch.
A. 0.75 inch and 5 threads/inch C. 0.50 inch and 5
threads/inch
B. 0.75 inch and 4 threads/inch D. 0.50 inch and 4
threads/inch
20. Two shafts 3.6 m between centers carry pulleys 1.2 m in diameter and
0.91 m in diameter respectively, connected by a crossed belt. It is
desired to put the belt on as an open belt. How long a piece must be
cut of it?
A. 300 mm B. 350 mm C. 400 mm D. 250 mm
21. A flat belt is 6 inches wide and 1/3 inch thick and transmits 15 Hp.
The center distance is 8 ft. The driving pulley is 6 inches in
diameter and rotates at 2000 rpm such that the loose side of the belt
is on top. The driven pulley is 18 inches in diameter. The belt
material is 0.035 lb/in3 and the coefficient of friction is 0.30.
Determine the net belt tension.
A. 167.56 lb B. 157.56 lb C. 156.75 lb D. 175.56 lb
22. Two pulleys, 80 cm apart, carry a belt in an open connection. If the
diameter of the pulleys are 40 cm and 15 cm, what is the length of the
belt needed?
A. 248.35 cm B. 348.35 cm C. 265.45 cm D. 305.35 cm
23. A pulley 600 mm in diameter transmits 40 KW at 500 rpm. The arc of
contact between the belt and pulley is 144o , the coefficient of
friction between belt and pulley is 0.35 and the safe working stress
of the belt is 2.1 Mpa. Determine the belt tension ratio, neglecting
the effect of centrifugal force.
A. 2.41 B. 2.14 C. 1.24 D. 4.12
24. A disc clutch has 6 pairs of contacting friction surfaces with an
outside diameter of 200 mm and an inside diameter of 100 mm. The
coefficient of friction of the clutch materials is 0.4 and the axial
force is 1500 N. The shaft speed is 1200 rpm. Find the Hp that can be
transmitted by the clutch assuming uniform pressure.
A. 35.2 Hp B. 23.5 Hp C. 47.2 Hp D. 27.4 Hp
