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Karnataka SSLC Elements of Mechanical Engineering IV - JTS (KSEAB) study materials
Karnataka SSLC Elements of Mechanical Engineering IV - JTS (KSEAB) study resources

Karnataka SSLC Elements of Mechanical Engineering IV - JTS (KSEAB) practice questions

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Question 1Engineering Materials and Their Properties

In the Karnataka SSLC Elements of Mechanical Engineering syllabus, which property of a metal describes its ability to be drawn into thin wires without fracture?

  1. Malleability
  2. Brittleness
  3. Elasticity
  4. Ductility Correct answer.

Explanation

Ductility is the property that allows a material to undergo permanent deformation by tension, so it can be pulled into wires such as copper and aluminium conductors. Malleability also involves permanent deformation but under compressive hammering into sheets, so the two are distinguished by the type of loading.

Question 2Engineering Materials and Their Properties

A workshop specimen is loaded in tension and returns exactly to its original length after unloading. Which property is being demonstrated?

  1. Toughness
  2. Plasticity
  3. Creep
  4. Elasticity Correct answer.

Explanation

Elasticity is the ability of a material to regain its original shape and dimensions when the applied load is removed, and the strain disappears completely. Plasticity would leave a permanent set, while toughness relates to energy absorbed before fracture and creep is slow deformation under sustained load.

Question 3Engineering Materials and Their Properties

Which material is most commonly used for the cutting tool tip of a hand hacksaw blade because it retains hardness at the cutting edge?

  1. Cast iron
  2. Mild steel
  3. High carbon steel Correct answer.
  4. Aluminium

Explanation

High carbon steel contains roughly 0.6 to 1.5 percent carbon, which allows it to be hardened and tempered so the teeth stay hard enough to cut metal. Low carbon steel and aluminium are too soft, and cast iron is brittle and not suited to a thin toothed blade.

Question 4Engineering Materials and Their Properties

Which of the following is a non-ferrous metal commonly chosen for electrical conductors because of its high electrical conductivity?

  1. Copper Correct answer.
  2. High carbon steel
  3. Pig iron
  4. Wrought iron

Explanation

Copper is a non-ferrous metal with very high electrical conductivity, so it is widely used for cables, windings and contacts. The other three options are ferrous materials, and their electrical resistivity is much higher than that of copper.

Question 5Engineering Materials and Their Properties

In a tensile test, the maximum stress a material can withstand before it begins to neck and eventually fracture is called the

  1. proof stress
  2. ultimate tensile strength Correct answer.
  3. yield stress
  4. elastic limit

Explanation

The ultimate tensile strength is the highest engineering stress reached on the stress-strain curve, after which local necking begins and the load needed to continue stretching falls. Yield stress marks the start of plastic flow, proof stress is an offset measure of yielding, and the elastic limit is the end of fully recoverable strain.

Question 6Engineering Materials and Their Properties

A component must resist repeated reversed loading in service without developing fatigue cracks. Which property should guide the material selection?

  1. Fatigue strength Correct answer.
  2. Thermal conductivity
  3. Hardness
  4. Density

Explanation

Fatigue strength is the stress level a material can endure for a specified number of repeated load cycles without failure, so it directly addresses reversed cyclic loading. Hardness, thermal conductivity and density affect other behaviours and do not by themselves describe resistance to cyclic crack initiation.

Question 7Engineering Materials and Their Properties

A bearing material is required to run against a rotating steel shaft with low friction and to embed small dirt particles. Which property combination is most important?

  1. Low thermal expansion with high stiffness
  2. High magnetic permeability with high strength
  3. Good conformability with low friction coefficient Correct answer.
  4. High brittleness with high hardness

Explanation

Bearing alloys such as white metal and bronze are chosen for conformability, which lets them bed into the shaft and embed grit, together with a low friction coefficient to reduce wear and heat. Brittleness, stiffness or magnetic permeability do not serve the sliding contact requirement.

Question 8Engineering Materials and Their Properties

The percentage of carbon in mild steel lies approximately in the range

  1. 3.0 to 4.0 percent
  2. 1.5 to 2.0 percent
  3. 0.05 to 0.25 percent Correct answer.
  4. 0.6 to 0.9 percent

Explanation

Mild steel, also called low carbon steel, contains about 0.05 to 0.25 percent carbon, which makes it soft, ductile and readily weldable for structural work. Medium carbon steel lies around 0.3 to 0.6 percent, high carbon steel above about 0.6 percent, and cast iron typically above 2 percent.

Question 9Engineering Materials and Their Properties

Which heat treatment process involves heating steel above its critical temperature, then cooling it slowly in the furnace to relieve internal stresses and soften it?

  1. Annealing Correct answer.
  2. Case hardening
  3. Quenching
  4. Tempering

Explanation

Annealing is a full heat treatment in which the steel is heated above the critical temperature and cooled very slowly, usually in the furnace, refining the grain and relieving internal stresses. Quenching is rapid cooling to harden, case hardening adds a hard surface layer, and tempering is a lower-temperature treatment after hardening.

Question 10Engineering Materials and Their Properties

A die for sheet metal blanking must have a very hard, wear-resistant working edge while the body remains tough. Which treatment best achieves this?

  1. Annealing followed by normalising
  2. Full annealing at high temperature
  3. Stress relieving only
  4. Hardening followed by tempering Correct answer.

Explanation

Hardening by quenching develops a hard martensitic structure, and a subsequent tempering treatment restores some toughness and relieves quenching stresses, giving a hard yet durable die edge. Annealing and normalising soften the steel, which would make the cutting edge wear rapidly.

Question 11Engineering Materials and Their Properties

Which test is used to assess the toughness of a material by measuring the energy absorbed when a notched specimen is broken by a single blow?

  1. Brinell hardness test
  2. Vickers hardness test
  3. Izod impact test Correct answer.
  4. Rockwell hardness test

Explanation

The Izod impact test swings a heavy pendulum against a notched specimen and records the energy absorbed in breaking it, which is a direct measure of toughness. Brinell, Rockwell and Vickers are all indentation hardness tests and do not measure impact energy.

Question 12Engineering Materials and Their Properties

In the Brinell hardness test, the hardness number is calculated from the diameter of the indentation produced by

  1. a diamond cone pressed with a minor load
  2. a hardened chisel struck by a hammer
  3. a hardened steel ball pressed with a known load Correct answer.
  4. a diamond pyramid pressed with a known load

Explanation

The Brinell test presses a hardened steel ball of standard diameter into the specimen under a known load and computes hardness from the resulting indentation diameter. The diamond cone belongs to the Rockwell test, the diamond pyramid to Vickers, and the chisel to the old dynamic hardness methods.

Question 13Engineering Materials and Their Properties

Which of the following is the chief reason for alloying nickel into steel?

  1. To increase toughness and corrosion resistance Correct answer.
  2. To lower the melting point below that of aluminium
  3. To make the steel a good electrical insulator
  4. To eliminate the need for any heat treatment

Explanation

Nickel is added to steel to improve toughness, hardenability and resistance to corrosion, and it is a major element in stainless and case-hardening steels. It does not lower the melting point below aluminium, does not make steel an insulator, and does not remove the need for heat treatment.

Question 14Engineering Materials and Their Properties

Stainless steel resists rusting mainly because of the presence of

  1. carbon
  2. chromium Correct answer.
  3. phosphorus
  4. sulphur

Explanation

Chromium in stainless steel forms a thin, adherent oxide film on the surface that protects the metal from further attack, and a content of at least about 10.5 percent is needed. Sulphur and phosphorus are harmful impurities, while carbon affects hardness and strength but does not provide the passive film.

Question 15Engineering Materials and Their Properties

A machine bed is made of cast iron rather than steel. Which property of cast iron best justifies this choice?

  1. High damping capacity for vibrations Correct answer.
  2. Very high tensile ductility
  3. High electrical conductivity
  4. Low compressive strength

Explanation

Grey cast iron has excellent damping capacity because the flake graphite absorbs vibration energy, which keeps a machine bed stable during cutting. Cast iron is brittle with low tensile ductility, is strong in compression, and is not chosen for electrical conductivity.

Question 16Engineering Materials and Their Properties

A shaft must transmit torque while remaining light, and it must resist corrosion in a marine atmosphere. Which material choice best satisfies these requirements?

  1. White cast iron
  2. High carbon tool steel
  3. Aluminium alloy with suitable alloying additions Correct answer.
  4. Grey cast iron

Explanation

Aluminium alloys combine low density with useful strength and, with suitable alloying elements such as magnesium or through anodising, can resist marine corrosion. Cast irons are heavy and brittle, and high carbon tool steel is dense and needs protection against a salt atmosphere.

Question 17Engineering Materials and Their Properties

Which of the following best explains why a thin layer of white metal is used in a shell bearing instead of making the whole bearing from white metal?

  1. White metal has higher thermal conductivity than steel
  2. White metal is stronger than the shell material
  3. The soft lining provides a low-friction running surface while the strong shell carries the load Correct answer.
  4. The lining increases the weight of the bearing

Explanation

White metal is soft and has good conformability and low friction, but it is weak, so it is applied as a thin lining on a strong steel or bronze shell that carries the load. The lining is not chosen for strength, weight or thermal conductivity.

Question 18Engineering Materials and Their Properties

Two steel specimens have the same composition, but one is quenched and the other is annealed. Compared with the annealed specimen, the quenched specimen will generally show

  1. higher hardness and lower ductility Correct answer.
  2. lower strength and higher toughness
  3. higher ductility and lower hardness
  4. identical hardness and ductility

Explanation

Rapid quenching traps carbon in a distorted martensitic lattice, which raises hardness and strength but reduces ductility and toughness. Annealing allows slow diffusion and produces a softer, more ductile structure, so the two specimens behave very differently despite identical composition.

Question 19Engineering Materials and Their Properties

A steel component shows a clear upper and lower yield point in its tensile test. What does the lower yield point represent?

  1. The maximum stress the specimen can carry before necking
  2. The stress at which elastic deformation begins
  3. The stress at which Lüders bands propagate and plastic deformation continues at nearly constant stress Correct answer.
  4. The stress at which the specimen finally fractures

Explanation

In low carbon steel the upper yield point is followed by a drop, and the lower yield point is the stress at which deformation bands spread along the gauge length while the load stays almost constant. The ultimate strength, fracture stress and start of elastic loading are different points on the curve.

Question 20Engineering Materials and Their Properties

Which of the following statements about the effect of carbon content on plain carbon steel is correct?

  1. As carbon increases, hardness and tensile strength increase while ductility decreases Correct answer.
  2. Carbon content has no effect on the mechanical properties of steel
  3. As carbon increases, hardness increases and ductility also increases
  4. As carbon increases, tensile strength falls and ductility rises

Explanation

Carbon forms hard cementite in the steel, so raising the carbon content increases hardness and tensile strength but reduces ductility and impact toughness. This is why low carbon steel is used for forming and welding while high carbon steel suits tools and springs.

Question 21Engineering Materials and Their Properties

Which material is a thermosetting plastic commonly used for electrical switch bodies and handles because it does not soften on reheating?

  1. Bakelite Correct answer.
  2. Polythene
  3. Polyvinyl chloride
  4. Nylon

Explanation

Bakelite is a phenol-formaldehyde thermosetting plastic that cures permanently and cannot be softened again by heat, so it is well suited to switch bodies and handles. Polythene, PVC and nylon are thermoplastics that soften when heated.

Question 22Engineering Materials and Their Properties

In a workshop, a copper wire and a steel wire of the same length and diameter are compared. Which statement about their electrical behaviour is correct?

  1. Both have identical resistivity because both are metals
  2. Copper has lower resistivity, so it carries current with less loss than steel Correct answer.
  3. Copper has higher resistivity but is chosen for its strength
  4. Steel has lower resistivity, so it is preferred for windings

Explanation

Copper has a much lower electrical resistivity than steel, so for a given length and cross-section it dissipates less power as heat. This is why copper is preferred for windings and conductors even though steel is stronger.

Question 23Engineering Materials and Their Properties

Which of the following is the main constituent of pig iron obtained from a blast furnace?

  1. Pure iron with no carbon at all
  2. Iron with about 3 to 4 percent carbon and other impurities Correct answer.
  3. An alloy of copper and zinc
  4. Iron with less than 0.1 percent carbon

Explanation

Pig iron is the crude product of the blast furnace and contains roughly 3 to 4 percent carbon along with silicon, manganese, sulphur and phosphorus. It is remelted in a cupola or refined to make cast iron and steel, and it is far from pure iron.

Question 24Engineering Materials and Their Properties

Which property describes the ability of a material to resist scratching, indentation and abrasion on its surface?

  1. Toughness
  2. Creep resistance
  3. Hardness Correct answer.
  4. Malleability

Explanation

Hardness is the resistance of a surface to local penetration, scratching or wear, and it is measured by indentation tests such as Brinell and Rockwell. Toughness concerns energy absorption before fracture, malleability concerns forming into sheets, and creep resistance concerns slow deformation under sustained load.

Question 25Hand Tools, Measuring Instruments and Workshop Practice

A fitter needs to hold a hexagonal nut securely while tightening it with a spanner. Which hand tool is designed specifically for gripping and turning such nuts and bolts?

  1. Scriber
  2. Spanner Correct answer.
  3. Bench vice
  4. Try square

Explanation

A spanner is the hand tool whose jaws are shaped to grip the flats of a nut or bolt head and apply turning torque. The bench vice holds work, the try square checks squareness, and the scriber marks lines, so none of them turn fasteners.

Question 26Hand Tools, Measuring Instruments and Workshop Practice

In a workshop, the tool used to strike a chisel while chipping metal is a hammer. Which part of a ball peen hammer is hardened and slightly domed for striking?

  1. The handle
  2. The face Correct answer.
  3. The wedge
  4. The eye

Explanation

The face is the hardened, slightly domed striking end of the hammer head that contacts the chisel or punch. The handle is held, the wedge secures the head on the handle, and the eye is the hole into which the handle fits.

Question 27Hand Tools, Measuring Instruments and Workshop Practice

A vernier caliper has a main scale with 1 mm divisions and a vernier scale of 10 divisions that exactly cover 9 mm on the main scale. What is the least count of this instrument?

  1. 0.1 mm Correct answer.
  2. 0.5 mm
  3. 0.01 mm
  4. 1 mm

Explanation

Least count equals the smallest main scale division divided by the number of vernier divisions, so 1 mm ÷ 10 = 0.1 mm. This is the smallest difference the instrument can read reliably.

Question 28Hand Tools, Measuring Instruments and Workshop Practice

While measuring a shaft with a micrometer, the barrel (sleeve) reads 7.5 mm and the thimble reading is 28 divisions. If the least count is 0.01 mm, what is the total reading?

  1. 7.528 mm
  2. 7.5 mm
  3. 7.78 cm
  4. 7.78 mm Correct answer.

Explanation

The thimble contributes 28 × 0.01 mm = 0.28 mm, which is added to the barrel reading of 7.5 mm to give 7.78 mm. The barrel reading already includes the half-millimetre mark, so the thimble value is simply added.

Question 29Hand Tools, Measuring Instruments and Workshop Practice

A try square is placed against a machined edge to check a filed surface. What property of the work does the try square verify?

  1. Parallelism of two opposite faces
  2. Squareness of two adjoining surfaces Correct answer.
  3. Hardness
  4. Surface roughness

Explanation

The stock of a try square is held against a true edge and the blade is brought to the adjoining surface; any gap or light shows that the two are not at 90 degrees. It therefore checks squareness, not roughness, hardness or parallelism of opposite faces.

Question 30Hand Tools, Measuring Instruments and Workshop Practice

A scriber is used to lay out lines on a steel plate before cutting. Which practice keeps the scribed line accurate and the point serviceable?

  1. Use the scriber point as a centre punch
  2. Hold the scriber vertical and drag it once with light pressure
  3. Scratch the line repeatedly with heavy pressure to make it deep
  4. Tilt the scriber at about 60 degrees to the surface and draw a single firm line Correct answer.

Explanation

A scriber is held inclined at roughly 60 degrees to the surface and drawn once with steady pressure so the point cuts a clean, thin line. Repeated heavy scratching widens the line and blunts the hardened point.

Question 31Hand Tools, Measuring Instruments and Workshop Practice

Which measuring instrument is most suitable for transferring a dimension from a drawing directly to a workpiece and then checking it, without any scale reading?

  1. Bevel protractor
  2. Vernier height gauge
  3. Outside micrometer
  4. Divider Correct answer.

Explanation

A divider has two pointed legs that are set to a dimension taken from a rule or drawing and then used to step off or transfer that distance on the work. It transfers a size rather than reading a numerical value.

Question 32Hand Tools, Measuring Instruments and Workshop Practice

A file is described by its length, cut and shape. Which file cut is intended for removing metal rapidly during rough filing of a mild steel block?

  1. Single cut, smooth
  2. Single cut, second cut
  3. Curved tooth, smooth
  4. Double cut, rough Correct answer.

Explanation

A double-cut rough file has coarse, crossing teeth that take deep bites and remove metal quickly for roughing. Smooth and second-cut files are used for finishing, where less material and a finer surface are wanted.

Question 33Hand Tools, Measuring Instruments and Workshop Practice

A hacksaw blade of 300 mm length is specified as 18 teeth per inch. What does the tooth pitch mainly determine when selecting the blade?

  1. The colour of the blade
  2. The thickness of material the blade can cut efficiently Correct answer.
  3. The angle of the file cut
  4. The length of the saw frame

Explanation

Tooth pitch decides how the blade behaves in different section thicknesses: coarse pitches clear chips in thick sections, while fine pitches suit thin tubes and sheet. Selecting the right pitch prevents the blade snagging or clogging.

Question 34Hand Tools, Measuring Instruments and Workshop Practice

When tapping a hole by hand, which sequence of tools is used to produce an internal thread in a drilled hole?

  1. Reamer, then broach
  2. Centre punch, then drill only
  3. Taps in taper, plug and bottoming order Correct answer.
  4. Die, then die stock

Explanation

Internal threads are cut with a set of taps; the taper tap starts the thread, the plug tap follows, and the bottoming tap finishes near the hole bottom. Dies cut external threads, and reamers or broaches do not produce screw threads.

Question 35Hand Tools, Measuring Instruments and Workshop Practice

A hole is to be drilled in a steel plate and the drill must start exactly at a marked point. Which sequence of operations is correct?

  1. Scribe a circle, then ream the hole
  2. Centre punch the mark, then drill Correct answer.
  3. Use a chisel to start the hole, then drill
  4. Drill first, then centre punch the mark

Explanation

A centre punch is struck at the marked intersection to create a conical depression that guides the drill point and prevents it wandering. Drilling before punching loses the location, and reaming or chiselling does not start a hole accurately.

Question 36Hand Tools, Measuring Instruments and Workshop Practice

A surface plate is used as a datum for marking and inspection. Why must it be kept clean and free of burrs before use?

  1. Burrs improve the grip on the workpiece
  2. Dirt helps the marking blue to stick
  3. Burrs and dirt raise the work unevenly and destroy the datum accuracy Correct answer.
  4. Burrs make the plate heavier and more stable

Explanation

A surface plate provides a flat reference plane; any dirt or burr under the work tilts it and makes heights and markings inaccurate. Cleaning the plate and the workpiece preserves the datum for both marking and inspection.

Question 37Hand Tools, Measuring Instruments and Workshop Practice

Which tool is used with a surface plate to mark heights and to check the height of a workpiece above the plate?

  1. Ball peen hammer
  2. Cold chisel
  3. Vernier height gauge Correct answer.
  4. Inside caliper

Explanation

A vernier height gauge stands on the surface plate, and its scriber arm is set to a scale reading to mark or check heights above the plate. Calipers, hammers and chisels do not give a height reading from a datum.

Question 38Hand Tools, Measuring Instruments and Workshop Practice

A bevel protractor is set to measure the angle between two faces of a machined bracket. If the main scale reads 40 degrees and the vernier coincides at the 30-minute mark, what is the measured angle?

  1. 43 degrees
  2. 30 degrees 40 minutes
  3. 40 degrees 30 minutes Correct answer.
  4. 40.30 degrees

Explanation

The main scale gives whole degrees and the vernier gives minutes, so a main reading of 40 degrees with a vernier coincidence at 30 minutes is written 40 degrees 30 minutes. Minutes are not written as a decimal fraction of a degree on this instrument.

Question 39Hand Tools, Measuring Instruments and Workshop Practice

A bench vice is mounted on a workbench for holding a job during filing. Which practice protects the job and the vice when clamping a finished surface?

  1. Tighten the vice as hard as possible on the bare jaws
  2. Fit soft jaws or clamp pads over the jaws Correct answer.
  3. Hold the job by hand instead of using the vice
  4. Place the job diagonally across the jaws

Explanation

Soft jaws or pads spread the clamping load and prevent the hardened, serrated jaws from marking a finished surface. Overtightening bare jaws or holding the job diagonally gives poor grip and damages the work.

Question 40Hand Tools, Measuring Instruments and Workshop Practice

In a fitter's shop, the term 'allowance' is used when deciding the size of mating parts. What does allowance refer to?

  1. The intentional difference between the sizes of two mating parts Correct answer.
  2. The hardness difference between two metals
  3. The unintentional variation in a machined dimension
  4. The total length of the workpiece

Explanation

Allowance is the deliberate, designed difference between the sizes of mating parts, which fixes the type of fit such as clearance or interference. It is a planned value, unlike tolerance, which is the permitted variation in a single dimension.

Question 41Hand Tools, Measuring Instruments and Workshop Practice

A shaft and hole are specified so that the shaft is always slightly larger than the hole before assembly, requiring force or heat to assemble. Which type of fit is this?

  1. Transition fit
  2. Sliding fit
  3. Interference fit Correct answer.
  4. Clearance fit

Explanation

In an interference fit the shaft size is greater than the hole size, so assembly needs pressing, shrinking or heating and the joint transmits load without a key. Clearance and sliding fits leave a gap, and a transition fit may give either a small gap or a small interference.

Question 42Hand Tools, Measuring Instruments and Workshop Practice

A hole is dimensioned as 25.00 +0.05/-0.00 mm. What is the tolerance on this hole?

  1. 0.00 mm
  2. 25.05 mm
  3. 50 mm
  4. 0.05 mm Correct answer.

Explanation

Tolerance is the difference between the upper and lower limits, here 25.05 mm minus 25.00 mm, which equals 0.05 mm. It expresses the total permitted variation in the hole size.

Question 43Hand Tools, Measuring Instruments and Workshop Practice

A cold chisel is used to chip a groove in a steel plate. Which point angle is normally ground on a cold chisel for general work on mild steel?

  1. About 90 degrees
  2. About 60 degrees Correct answer.
  3. About 120 degrees
  4. About 30 degrees

Explanation

A cold chisel for general work on mild steel is ground to a point angle of about 60 degrees, which balances a keen edge with enough strength to resist chipping. Softer metals allow a sharper angle, while harder metals need a blunter one.

Question 44Hand Tools, Measuring Instruments and Workshop Practice

Which of these operations is a bench-fitting operation performed with a hand reamer?

  1. Cutting an external thread on a rod
  2. Checking the angle of a machined face
  3. Enlarging a drilled hole to an accurate size with a smooth finish Correct answer.
  4. Chipping a keyway in a shaft

Explanation

A hand reamer removes a small amount of material from a drilled hole to bring it to an accurate diameter with a smooth internal finish. Threading, chipping and angle checking use dies, chisels and protractors respectively.

Question 45Hand Tools, Measuring Instruments and Workshop Practice

A fitter must remove a broken tap from a blind hole without damaging the thread. Which approach is most appropriate?

  1. Re-drill the hole with a larger drill and abandon the thread
  2. Drive the broken piece deeper with a punch
  3. Use a tap extractor or spark-erode the broken piece out Correct answer.
  4. Strike the broken tap sideways with a hammer

Explanation

A tap extractor engages the flutes of the broken tap so it can be unscrewed, and for stubborn cases spark erosion removes the piece without harming the surrounding thread. Driving or hammering the tap damages the hole, and re-drilling destroys the thread.

Question 46Hand Tools, Measuring Instruments and Workshop Practice

When using a hand hacksaw, the blade is fitted so that the teeth point away from the handle. Why is this orientation used?

  1. So that the blade cuts only on the return stroke
  2. So that the blade lasts longer between sharpenings
  3. So that the frame can be shortened
  4. So that the saw cuts on the forward (push) stroke Correct answer.

Explanation

Hacksaw teeth are set to cut on the forward push stroke, which is the stroke over which the operator can apply steady force and control. Fitting the blade the other way round makes it cut on the weaker return stroke and shortens blade life.

Question 47Hand Tools, Measuring Instruments and Workshop Practice

A dial test indicator is mounted on a magnetic stand and its plunger is brought against a rotating shaft. What does the variation in the dial reading indicate?

  1. The runout or eccentricity of the shaft Correct answer.
  2. The hardness of the shaft surface
  3. The length of the shaft
  4. The surface roughness of the shaft

Explanation

As the shaft rotates, the indicator plunger follows the surface and the swing on the dial shows the total runout, that is, how far the surface departs from a true circle about the axis. It does not measure hardness, roughness or length.

Question 48Hand Tools, Measuring Instruments and Workshop Practice

Which of the following is the correct way to store precision measuring instruments such as vernier calipers and micrometers after use?

  1. Store them with the jaws tightly closed to protect the points
  2. Clean them, release the lock, leave a small gap between measuring faces and store in a case Correct answer.
  3. Oil the scale heavily and store them open on a shelf
  4. Leave them on the bench with jaws closed and locked

Explanation

Precision instruments should be wiped clean, the locking screw released so no stress remains, and the measuring faces left slightly apart to avoid rusting or sticking, then kept in their case. Tightly closed jaws or heavy oil films damage the measuring faces and the scale.

Question 49Fasteners, Bearings, Seals and Fits

In a bolted joint, which designation correctly represents an M16 coarse thread with a pitch of 2 mm?

  1. M16 - 2
  2. M16 / 2
  3. M16 × 2 Correct answer.
  4. 16M × 2

Explanation

ISO metric thread designation places the letter M first, then the nominal diameter, and where pitch differs from coarse it is added after a multiplication sign. Hence M16 × 2 means a metric thread of 16 mm nominal diameter with 2 mm pitch. A plain M16 without pitch implies the standard coarse pitch.

Question 50Fasteners, Bearings, Seals and Fits

A hexagonal bolt head is specified as 24 A/F. What does the abbreviation indicate?

  1. Allowable force in kN
  2. Angle of the chamfer on the head
  3. Thread length of the bolt
  4. Across-flats distance of the head Correct answer.

Explanation

A/F stands for across flats, the distance measured between two opposite flat faces of a hexagonal head. This dimension decides the size of spanner required to tighten or loosen the bolt. It is independent of the thread length or strength of the fastener.