Class 11 Automotive Service Technician Chapter 2 Fasteners

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Class 11 Automotive Service Technician Chapter 2 Fasteners

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Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. Class 11 Automotive Service Technician Chapter 2 Fasteners Textual Solutions are part of All Subject Solutions. Here we have given AHSEC Class 11 Automotive Service Technician Chapter 2 Fasteners Textbook Solutions English Medium for All Chapters, You can practice these here.

Fasteners

Chapter: 2

A. Fill in the blanks: 

1. A fastener is a hardware __________ that mechanically joins or __________ two or more objects together. 

Ans: Device, Affixes.

2. Automotive fasteners are made up of a variety of _____________. 

Ans: Stainless steel.

3. A bolt is an externally threaded _________. 

Ans: Fastener.

4. External threads are on the __________ or screws and internal threads are on the __________. 

Ans: Studs, bolts.

5. In India we use ISO __________ thread.

Ans: Metric.

B. Multiple choice questions:

1. Which automotive fastener(s) is (are) used for holding or connecting two or more objects in a machine?

(a) Nuts and bolts.

(b) Wooden keel.

(c) Fibre joint. 

(d) None of the above.

Ans: (a) Nuts and bolts.

2. What is the simple effective diameter of a screw thread? 

(a) Pitch diameter. 

(b) Flank. 

(c) Root. 

(d) Threaded angle.

Ans: (a) Pitch diameter. 

3. What are the straight sides, which connect the crest and the root called? 

(a) Flank.

(b) Root. 

(c) Minor diameter. 

(d) Pitch diameter. 

Ans: (a) Flank. 

 4. Match the following:

Ans: (a) Eye bolt – Image 3

(b) Flange bolt – Image 1

(c) Frame bolt – Image 2

(d) Hanger bolt – Image 4

5. Choose sheet metal screw on the basis of the head shape shown here.

Ans: (c) 

C. Answer the following questions:

1. Describe the importance of bolts.

Ans: Automotive bolts and machine screws are also known as threaded fasteners. They are effective at joining multiple objects. Fasteners have a threaded pin or rod with a head at one end. An automotive bolt is inserted through holes in the assembled parts and fixed firmly with a mated nut with the help of a torque. The bolt and nut are tightened by holding the bolt head stationary and turning the nut for tightening. 

 2. What are machine screws?

Ans: A machine screw is an outside threaded fastener. On the top of a screw is a head, which is used to drive the screw into the object. An automotive bolt with a common head can work as a screw, and can be driven into a hole by the head. Usually, the machine screws are fully threaded.

3. What is the importance of threads on bolt and machine screws?

Ans: A bolt thread is a ridge of uniform section in the form of a helix on either the external or internal surface of the cylinder. Internal threads refer to those on nuts and tapped holes and external threads are those on bolts, studs, or screws. The helix of a thread can twist in two possible directions — right hand (RH) or left hand (LH).

4. Differentiate between bolt and screw.

Ans: The differences between bolt and screw are as under:

5. What do you understand by metric thread? Make a profile of metric thread and state all the terminologies.

Ans: A metric thread is defined by its profile and it follows the ISO standards. The basic profile of an ISO metric thread includes the following parameters:

(i) D = Major diameter of internal thread (nut).

(ii) d = Major diameter of external thread (bolt).

(iii) D2 = Pitch diameter of internal thread.

(iv) d2 = Pitch diameter of external thread.

(v) D1 = Minor diameter of internal thread.

(vi) d1 = Minor diameter of external thread.

(vii) P = Pitch.

(viii) H = Height of fundamental triangle.

(ix) d = D = nominal diameter.

(x) d1 = D1 = d – 1.0825 P.

(xi) d2 = D2 = d – 0.6495 P.

(xii) P = Pitch.

(xiii) H = 0.866 P.

(xiv) r = 0.1443 P.

A. Fill in the blanks: 

1. A nut is a type of fastener with a _____________ hole. 

Ans: Threaded.

2. For joining two metal parts, the nut is screwed onto the _____________. 

Ans: Bolt.

3. The _____________ of the bolt and nut must be same else the nut cannot be _____________ on the bolt. 

Ans: Pitch, screwed.

4. A nut can have left hand or right hand _______________ threads. 

Ans: Internal.

5. A hexagonal nut is a type of metal fastener that has _____________ sides.

Ans: Six.

B. Multiple choice questions:

1. Which factor of the bolt and nut must be the same for the nut to be screwed on the bolt? 

(a) Pitch.

(b) Minor diameter.

(c) Root.

(d) Flank.

Ans: (a) Pitch.

2. Which of the following is a hexagonal nut?

Ans: (a) 

3. Which nut is used to join two externally threaded rods together? 

(a) Coupling. 

(b) K-lock or Kep. 

(c) Square. 

(d) None of the above.

Ans: (a) Coupling. 

4. Which nut is used specifically in automotive bearing or wheel hub to spindle assemblies? 

(a) Slotted Hex Nuts.

(b) Prevailing torque lock.

(c) K-lock or Kep. 

(d) Square.

Ans: (a) Slotted Hex Nuts.

C. Answer the following questions: 

1. Describe the importance of nuts.

Ans: An automotive nut is a type of fastener with a threaded hole. It is used in conjunction with a mating bolt to hold together temporary or permanent structures. These nuts are generally square or hexagonal in shape. The thread profile of a bolt and nut must match for proper fitting. If the profile mismatches, it may damage the threads, making it difficult for the nut to fit on the bolt. Nuts come in various types, such as simple nuts, collar nuts, and locking nuts, each serving specific functions in ensuring secure assemblies. Nuts are made from a range of materials, including steel, brass, copper alloys, plastic, and stainless steel, to ensure durability and compatibility with different automotive components.

 2. Why are nuts made of four or six faces?

Ans: A nut is a type of fastener with a threaded hole. It is used opposite a mating bolt to hold together temporary or permanent structures. These nuts are generally square or hexagonal shaped.

3. What is the importance of threads in a nut?

Ans:  A nut is screwed onto a bolt for joining two metal parts. Therefore, the thread profile of a bolt and nut must match and since we use metric threads in India, the nut being used in conjunction with the bolt must have metric threads as well. Mismatching of the profile and forcible screwing may damage the thread profile of a nut and bolt, and the nut will not fit on the bolt. The nut may have left hand or right hand internal threads.

4. What do you understand by ISO metric thread?

Ans: In India, we use ISO metric threads where:

(i) D = Major diameter of internal thread (nut).

(ii) d = Major diameter of external thread (bolt).

(iii) D2 = Pitch diameter of internal thread.

(iv) d2 = Pitch diameter of external thread.

(v) D1 = Minor diameter of internal thread.

(vi) d1 = Minor diameter of external thread.

(vii) P = Pitch.

(viii) H = Height of fundamental triangle.

(ix) d = D = nominal diameter.

(x) d1 = D1 = d – 1.0825 P.

(xi) d2 = D2 = d – 0.6495 P.

(xii) P = Pitch.

(xiii) H = 0.866 P.

(xiv) r = 0.1443 P.

5. Name the different types of nuts.

Ans: The different types of nuts are:

(i) Hex.

(ii) Heavy hex.

(iii) Nylon insert lock.

(iv) Jam.

(v) Nylon insert jam lock.

(vi) Wing.

(vii) Cap.

(viii) Acorn.

(ix) Flange.

(x) Tee.

(xi) Square.

6. Name the different types of machine screws.

Ans: The different types of machine screws are:

(i) Plain Machine Screws.

(ii) Self-tapping Screws.

(iii) Hexagon Head Screws.

(iv) Countersunk Screws.

(v) Round Head Screws.

(vi) Pan Head Screws.

(vii) Socket Head Screws.

(viii) Flat Head Screws.

(ix) Button Head Screws.

(x) Set Screws.

A. Fill in the blanks: 

1. Studs are mechanical ___________ which are ____________ on one or both ends. 

Ans: Fasteners, threaded.

2. Automotive studs are _______________________ at both the ends. 

Ans: Threaded.

3. Wheel studs are the threaded fasteners that hold on the ____________ of automobiles. 

Ans: Wheel.

4. Press-in studs are installed from the back side of the ____________ or ____________. 

Ans: Disc or drum hub.

5. For a performance or ____________ application, the use of ____________ is preferred whenever possible instead of main cap bolts.

Ans: Heavy duty, main studs

B. Multiple choice questions: 

1. Fasteners which are threaded on one or both ends are known as _____________. 

(a) Studs. 

(b) Welding. 

(c) Casting. 

(d) Rivets 

Ans: (a) Studs.

2. On the basis of their usage, automotive studs can be categorised as __________________. 

(a) Engine studs. 

(b) Wheel studs. 

(c) Stainless steel studs. 

(d) All of the above. 

Ans: (d) All of the above. 

3. Wheel studs are used in automobiles for ____________. 

(a) Holding the wheels.

(b) Holding the chassis. 

(c) Holding the frame.

(d) All of the above. 

Ans: (a) Holding the wheels.

4. Main studs can replace ____________________. 

(a) Main cap bolts.

(b) Screw-in. 

(c) Press-in. 

(d) All of the above. 

Ans: (a) Main cap bolts.

5. Which wheel stud can be replaced if broken? 

(a) Screw-in and press-in.

(b) Engine studs.

(c) Stainless steel.

(d) All of the above.

Ans: (a) Screw-in and press-in.

C. Answer the following questions:

1. What are the advantages of studs over bolts? 

Ans: Studs are used for joining parts. Due to low tensile strength of cast iron, cast iron thread gets damaged in excessive tightening process. It leads to permanent damage to the casting. They are also used in gas and water-tight joints in applications, where heavy pressures are created. In automobiles, studs are used for holding down the cylinder head on a cylinder block of a motor car engine. The joint between the cylinder and the head should be a temporary one.

2. In what conditions should studs be used in place of bolts?

Ans: Studs should be used in place of bolts when there is limited space to insert a large part over the fastener, and the part needs to be slipped into place from the side. Also, studs are stronger than bolts, so they are better for situations where extra strength is needed.

3. Differentiate between bolt and stud.

Ans: The different between bolt and stud are:

4. Name the different types of studs.

Ans: On the basis of their usage, automotive studs can be categorised as:

(i) Engine studs.

(ii) Wheel studs.

(iii) Stainless steel studs.

A. Fill in the blanks:

1. A washer is a thin ____________ with a hole that is normally used to ____________ the load of a threaded ____________. 

Ans: Plate, distribute load, screw.

2. Automotive washers are small flat ____________ with a ____________ in the center. 

Ans: Dishes, holes.

3. Rivets are ____________ mechanical fasteners.

Ans: Semi-permanent.

4. Rivets are categorised on the basis of their ____________. 

Ans: Heads.

5. Circlips are often used to secure _____________. 

Ans: Pinned connections.

6. Split pins are typically made of ____________ metal, making them easy to ____________ and remove. 

Ans: Soft, fix.

7. Spring pins have a body diameter which is larger than the ____________ diameter, and a ____________ on either one or both ends to facilitate ____________ the pin into the hole.

Ans: Hole, chamfer, starting .

B. Multiple choice questions: 

1. A washer is used to distribute the load of a ___________. 

(a) Screw or nut.

(b) Chassis. 

(c) Wheel. 

(d) None of the above. 

Ans: (a) Screw or nut.

2. A washer’s outer diameter (OD) is twice the width of their ____________. 

(a) Inner diameter.

(b) Pitch.

(c) Flank. 

(d) None of the above.

Ans: (a) Inner diameter.

3. Which of these is a  flat washer?

Ans: (a) 

4. Which of the following types of washers is used in timber construction? 

(a) Square.

(b) Dock. 

(c) Ogee. 

(d) Split lock. 

Ans: (a) Square.

5. Which of the following is a semi-permanent mechanical fastener? 

(a) Rivet.

(b) Nut and bolt. 

(c) Studs. 

(d) None of the above.

Ans: (a) Rivet.

C. Answer the following questions: 

1. Describe the importance of washers.

Ans: A washer is a thin plate with a hole. It is normally used to distribute the load of a screw or nut. It acts as a spring, locking device, spacer, wear pad and also reduces vibration. A washer’s outer diameter (OD) is twice the width of its inner diameter (ID).

In the automotive industry, washers play a crucial role in holding or bearing the load of threaded fasteners, bolts, nuts, and joints. They are often placed beneath a nut, axle bearing, or joint to prevent leakage and distribute pressure evenly. Types of automotive washers include bolt lock washers, cylinder head washers, lug nut washers, radiator washers, and hardened washers. These fasteners are usually made from materials like metal, rubber, leather, or plastic.

2. What is the importance of rivets?

Ans: Rivets are semi-permanent mechanical fasteners. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. Rivets are used as automobile fasteners in a wide number of applications like vehicle bodies, aircraft, bridges, cranes, building frames, etc. Rivet is held in place and the metal parts are joined. The joint can be opened by removing the deformed end of the rivet by chisel or grinding.

3. What are the advantages of using washers as fasteners?

Ans: A washer is a thin plate with a hole. It is normally used to distribute the load of a screw or nut. It acts as a spring, locking device, spacer, wear pad, and also reduces vibration. A washer’s outer diameter (OD) is twice the width of its inner diameter (ID).

Automotive washers are small flat dishes with a hole in the center. The main function of an automotive washer is to hold or bear the load of a threaded fastener or bolt. Washers are put below a nut, axle bearing, or joint with the main purpose of preventing leakage and distributing pressure.

4. In what conditions should rivets be used as fasteners?

Ans: Rivets are semi-permanent mechanical fasteners. They are used as automobile fasteners in a wide number of applications like vehicle bodies, aircraft, bridges, cranes, building frames, etc. Rivet is held in place and the metal parts are joined. The joint can be opened by removing the deformed end of the rivet by chisel or grinding. Rivets are used when strength and fluid-tight joints are the main considerations.

5. What are the advantages of using split pins as fasteners?

Ans: A split pin is a metal fastener with two tines that are bent during installation. Split pins are generally made of soft metal, making them easy to install and remove. Common materials used in its manufacture may be mild steel, brass, bronze, stainless steel, and aluminium. A new split pin has its flat inner surfaces touching for most of its length so that it appears to be a split cylinder. Once inserted, the two ends of the pin are bent apart, locking it in place. When they are removed, they are supposed to be discarded and replaced, because of fatigue from bending.

6. What are the advantages of using a spring pin as a fastener?

Ans:A spring pin is a mechanical fastener that joins two or more parts of a machine relative to each other. Spring pins have a body diameter which is larger than the hole diameter, and a chamfer on either one or both ends to facilitate starting the pin into the hole. The spring action of the pin allows it to compress as it assumes the diameter of the hole. The radial force exerted by the pin against the hole wall retains it in the hole, therefore a spring pin is considered a self-retaining fastener.

7. Name different types of washers.

Ans: The different types of washers are:

(i) Flat Washer.

(ii) Fender Washer.

(iii) Finishing Washer.

(iv) Split Lock Washer.

(v) External Tooth Lock Washer.

(vi) Internal Tooth Lock Washer.

(vii) Square Plate Washer.

8. Name different types of rivets.

Ans: Rivets are categorized based on their heads. The common types include:

(i) Universal Head.

(ii) AN456 Pan Head.

(iii) Flat Top Countersunk Head.

(iv) Flat Head.

(v) Tinners’ Rivet.

(vi) Cone Head.

(vii) Round Top Countersunk Head.

(viii) Button Head.

(ix) Truss Head.

9. List the uses of circlip.

Ans: Circlips are often used to secure pinned connections. They are used to retain piston wrist pins or gudgeon pins. These clips are also known as wrist pin clips or wrist pin retainers or gudgeon pin clips. The most commonly used circlip for this application is a simple spring steel circlip (snap ring), or plain wire ring.

A. Fill in the blanks: 

1. In automobiles screws get broken due to ____________, vibration and ____________. 

Ans: Jerk, corrosion.

2. To remove a spoiled headed screw use hacksaw ____________ and dress the _______. 

Ans: Blade, groove.

3. In automobiles, due to ____________ movement and vibration, nuts and bolts get _______.

Ans: Jerky, damaged.

4. A stud is stronger than a ____________. 

Ans: Bolt.

5. Anti-rust solution is used for dissolving the ____________ in the fastener.

Ans: Dust.

B. Multiple choice questions: 

1. For removing a spoiled headed screw _______________. 

(a) Use a hacksaw blade and dress the groove. 

(b) Remove the screw, if it does not respond.

(c) Both of the above. 

(d) None of the above. 

Ans: (c) Both of the above.

2. Remove the unheaded screw if _______________________. 

(a) The screw is broken at the top of the assembly. 

(b) The other screw and separate the assembly. 

(c) Come out.

(d) All of the above.

Ans: (d) All of the above.

3. How to remove an unheaded screw broken in the assembly? 

(a) Dress the threads before fixing the new screw. 

(b) Drill into the centre of the screw, it will be removed. 

(c) Use a drill machine with a smaller drill bit than that of the screw.

(d) All of the above.

Ans: (d) All of the above.

C. Answer the following questions:

1. Give the process of removing screws with a spoiled head.

Ans: If the screwdriver keeps slipping, due to widening of the groove or screw way: 

(i) Use a hacksaw blade and dress the groove.

(ii) Then use a screwdriver with a thick snap, place it on the screw head and turn it anti-clockwise. 

(iii) This removes the screw, if it is not responded. 

(iv) Take a prick punch and hammer. Give a light blow in an anti clockwise direction. This loosens the screw. 

(v) If it does not work, use a drill machine with a drill bit smaller than the size of the screw. 

(vi) Now drill it at the centre of the screw, the screw will get removed. 

2. How is a screw without a head removed?

Ans: If the screw is broken at the top of the assembly: 

(i) Remove the other screw and separate the assembly.

(ii) Hold the jaws of the clipper on a broken screw.

(iii) Lock the clipper and turn it anti-clockwise.

(iv) The screw will come out.

3. List the steps to remove the unheaded screw broken in the assembly.

Ans: (i) Use a drill machine with a drill bit smaller than the size of the screw. 

(ii) Now drill it at the centre of the screw. The screw will get removed. 

(iii) Dress the threads before fixing a new screw.

4. Give the steps to remove broken or spoiled threaded studs.

Ans: Removal of spoiled threaded studs:

(i) To remove a spoiled threaded stud, apply gentle pressure on the assembly with a screwdriver. This will lift the spoiled portion of the stud threads upward.

(ii) Turn the nut anti-clockwise, turn the stud assembly and gently press the screw driver inside for the stud to come out.

(iii) If the nut threads, i.e., internal threads of the nut or external threads of the studs are spoiled, then weld the spot to nut and stud. Now turn the assembly anti-clockwise, and the stud will come out.

Removal of broken studs above the casing:

(i)  If the stud above the assembly unit is broken, separate the assembly by removing other nuts.

(ii)  Fix the stud extractor on the broken stud and lock it. 

(iii) Now turn the stud extractor slowly, the stud will come out.

Parimol

Hi! my Name is Parimal Roy. I have completed my Bachelor’s degree in Philosophy (B.A.) from Silapathar General College. Currently, I am working as an HR Manager at Dev Library. It is a website that provides study materials for students from Class 3 to 12, including SCERT and NCERT notes. It also offers resources for BA, B.Com, B.Sc, and Computer Science, along with postgraduate notes. Besides study materials, the website has novels, eBooks, health and finance articles, biographies, quotes, and more.