VAAL UNIVERSITY OF
TECHNOLOGY
Cover sheet for Test4
Faculty: Engineering
Department: Mechanical
Diploma: National Diploma: Engineering: Mechanical
Subject: Mechanical Engineering Design II
Date: 9 July 2021
Internal code: EMMED2A
Examiner: MD Mafoko
Moderator: AO Aniki
Hours: 120 min
Total Marks: 70 Full marks: 70
* Requirements: OPEN BOOK ASSESSMENT
* Instructions: Answer all the questions.
Signature of Examiner:…MD Mafoko……… Date: 9 June2021
Signature of Moderator:…Abimbola Aniki….. Date:………………
, Q1. Write two functions of sliding bearings.
a) To support shafts.
b) To reduce friction, wear and generation of heat.
c) To obtain high mechanical efficiencies inmoving mechanical systems.
2 marks
Q2. What are the two main categories of bearings?
a) Plain bearings or
b) Sliding bearings
c) Rolling elements bearings.
2 marks
Q3. In the name journal bearing, what does the journal stand for?
a) Part of the shaft that is support in the bearing.
1 mark
Q4. Which are the most common materials that plain bearings are made from?
a) Lead-based babbitt.
b) Tin-based babbitt.
2 mark
Q5. What is the lead content of lead-based babbitt material?
Seventy five percent or 75%.
1 mark
Q6. In marine applications of grooved rubber bearings supported in a metal housing,
what is the water used for?
Water is used for cooling the bearing and removal of foreign particles.
2 marks.
Q7. What is the significance of a bearing material being soft and malleable?
a) To embed foreign objects in the lubricant.
b) To compensate for slight bearing misalignment and shaft deflection.
2 marks
Q8. Name two types of lubricants and one example for each.
Type of lubricant Example
Liquid Oil, grease
Solid Teflon, graphite
Gas Compressed or pressurised gas.
4 marks
Q9. What of the function of additives in lubricants?
To improve lubricating properties of the lubricant.
1 mark
Q10. At 140OC, what would be the dynamic viscosity of an SAE 10 oil?
2 mPa.s
1 mark
Q11. The time measured in Saybolt seconds is a measure of what?
Viscosity, kinematic viscosity.
1 mark
TECHNOLOGY
Cover sheet for Test4
Faculty: Engineering
Department: Mechanical
Diploma: National Diploma: Engineering: Mechanical
Subject: Mechanical Engineering Design II
Date: 9 July 2021
Internal code: EMMED2A
Examiner: MD Mafoko
Moderator: AO Aniki
Hours: 120 min
Total Marks: 70 Full marks: 70
* Requirements: OPEN BOOK ASSESSMENT
* Instructions: Answer all the questions.
Signature of Examiner:…MD Mafoko……… Date: 9 June2021
Signature of Moderator:…Abimbola Aniki….. Date:………………
, Q1. Write two functions of sliding bearings.
a) To support shafts.
b) To reduce friction, wear and generation of heat.
c) To obtain high mechanical efficiencies inmoving mechanical systems.
2 marks
Q2. What are the two main categories of bearings?
a) Plain bearings or
b) Sliding bearings
c) Rolling elements bearings.
2 marks
Q3. In the name journal bearing, what does the journal stand for?
a) Part of the shaft that is support in the bearing.
1 mark
Q4. Which are the most common materials that plain bearings are made from?
a) Lead-based babbitt.
b) Tin-based babbitt.
2 mark
Q5. What is the lead content of lead-based babbitt material?
Seventy five percent or 75%.
1 mark
Q6. In marine applications of grooved rubber bearings supported in a metal housing,
what is the water used for?
Water is used for cooling the bearing and removal of foreign particles.
2 marks.
Q7. What is the significance of a bearing material being soft and malleable?
a) To embed foreign objects in the lubricant.
b) To compensate for slight bearing misalignment and shaft deflection.
2 marks
Q8. Name two types of lubricants and one example for each.
Type of lubricant Example
Liquid Oil, grease
Solid Teflon, graphite
Gas Compressed or pressurised gas.
4 marks
Q9. What of the function of additives in lubricants?
To improve lubricating properties of the lubricant.
1 mark
Q10. At 140OC, what would be the dynamic viscosity of an SAE 10 oil?
2 mPa.s
1 mark
Q11. The time measured in Saybolt seconds is a measure of what?
Viscosity, kinematic viscosity.
1 mark
