Friction Clutches: Single Plate Clutch
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Questions and Answers

What is the main purpose of a clutch in a mechanical system?

  • To change the direction of rotation of the gearbox shaft
  • To connect two shafts when desired (correct)
  • To cool down the system during operation
  • To increase the speed of the engine shaft

    • In a single plate clutch, what is the material of the clutch plate usually made of?

  • Copper
  • Rubber
  • Steel (correct)
  • Aluminum

    • What component presses the clutch plate against the flywheel when the clutch is engaged?

  • Flywheel
  • Spring-loaded pressure plate (correct)
  • Thrust bearing
  • Release lever

    • When a single plate clutch is disengaged, what component is pulled back to release the clutch?

    <p>Pressure plate</p> Signup and view all the answers

    How are the shafts connected in friction clutches?

    <p>By friction between rotating concentric surfaces</p> Signup and view all the answers

    What happens when the foot is taken off the clutch pedal in a mechanical system?

    <p>Pressure on the thrust bearing is released</p> Signup and view all the answers

    What is the formula for the normal load acting on the ring?

    <p>pr × 2pr.drcoseca</p> Signup and view all the answers

    In a conical friction clutch, what does the intensity of normal pressure vary inversely with?

    <p>Distance from the axis of the clutch</p> Signup and view all the answers

    What is the formula for finding axial spring force necessary to engage the clutch?

    <p>Wn (sin a+ µ cosa)</p> Signup and view all the answers

    What is the coefficient of friction in Example 1?

    <p>0.2</p> Signup and view all the answers

    What is the face angle in Example 1?

    <p>12.5º</p> Signup and view all the answers

    What is the width of the bearing surface in Example 2?

    <p>52.2 mm</p> Signup and view all the answers

    What is the maximum mean diameter of the clutch face in Example 1?

    <p>250 mm</p> Signup and view all the answers

    What does the torque transmitted formula take into account in a conical friction clutch?

    <p>$2p \times \mu \times pn \times R^2 \times b$</p> Signup and view all the answers

    What keeps the shoes of a centrifugal clutch against the boss on the driving shaft?

    <p>Spring force</p> Signup and view all the answers

    What is the formula for calculating the total force on the contact surface in a single plate clutch?

    <p>$2p \times C \times (r1 - r2)$</p> Signup and view all the answers

    When does the shoe remain in the same position as when the driving shaft was stationary?

    <p>When the centrifugal force is less than the spring force</p> Signup and view all the answers

    In a cone clutch, what holds the clutch faces in contact and maintains the pressure between them?

    <p>Spring around the driving shaft</p> Signup and view all the answers

    What is the formula for calculating torque transmitted in a cone clutch?

    <p>$2n \times \mu \times W \times R$</p> Signup and view all the answers

    What happens when the centrifugal force exceeds the spring force in a centrifugal clutch?

    <p>The shoe moves outward and presses against the driven member</p> Signup and view all the answers

    What is used for disengagement of the clutch in a cone clutch system?

    <p>Forked lever at point B</p> Signup and view all the answers

    What is the formula for the frictional torque acting on each shoe in a centrifugal clutch?

    <p>$F \times R$</p> Signup and view all the answers

    What does the area of contact of a shoe in a centrifugal clutch depend on?

    <p>The contact length of the shoe and width of the shoe</p> Signup and view all the answers

    What is the formula for calculating the normal load acting on a ring of the friction surface?

    <p>$p_n \times 2prdr\cosec(a)$</p> Signup and view all the answers

    How is the total frictional torque transmitted in a centrifugal clutch calculated?

    <p>$(P_c - P_s) \times R \times n$</p> Signup and view all the answers

    What does 'R' represent in the formula for torque transmitted in a cone clutch?

    <p>Mean radius of friction surface</p> Signup and view all the answers

    What is used to determine reasonable life intensity in a centrifugal clutch?

    <p>$p$</p> Signup and view all the answers

    In a single plate clutch, what should be known to determine the power transmitted by the clutch?

    <p>$N$ (speed)</p> Signup and view all the answers

    What is 'dl' in relation to a small ring of radius 'r' and thickness 'dr'?

    <p>Length of ring of friction surface</p> Signup and view all the answers

    What does $P_c - P_s$ represent in a centrifugal clutch?

    <p>$F$</p> Signup and view all the answers

    What is used to calculate the area of contact of a shoe pressing against a rim in a centrifugal clutch?

    <p>$l \times b \times p$</p> Signup and view all the answers

    What does 'µ' represent in the context of cone clutches?

    <p>Coefficient of friction between contact surfaces</p> Signup and view all the answers

    What holds the driven member in place on the driven shaft in a cone clutch?

    <p>Feather key on driven shaft</p> Signup and view all the answers

    What does $l \times b \times p$ represent in a centrifugal clutch?

    <p>Frictional force</p> Signup and view all the answers

    What is the value of the frictional force acting tangentially on each shoe?

    <p>156.5 m N</p> Signup and view all the answers

    What is the formula to calculate the torque transmitted (T)?

    <p>T = n.F.R</p> Signup and view all the answers

    What is the size of the shoes in mm?

    <p>67.3 mm</p> Signup and view all the answers

    What is the principle difference between absorption dynamometers and transmission dynamometers?

    <p>Absorption dynamometers absorb energy through friction while transmission dynamometers transfer energy without friction.</p> Signup and view all the answers

    What is the Prony brake dynamometer primarily used for?

    <p>Measuring brake power of an engine</p> Signup and view all the answers

    In a Prony brake dynamometer, what balances the brake when unloaded?

    <p>Counterweight at the other end of the lever</p> Signup and view all the answers

    What is required to prevent slipping of the rope over the flywheel in a Rope Brake Dynamometer?

    <p>Wooden blocks</p> Signup and view all the answers

    'N-m' represents which unit in engineering?

    <p>Newton-second per meter</p> Signup and view all the answers

    What does a torsion dynamometer measure?

    <p>Power</p> Signup and view all the answers

    In a torsion dynamometer, what does the amount of twist in the shaft depend on?

    <p>Torque, length, diameter, and modulus of rigidity</p> Signup and view all the answers

    What is the formula for power transmitted by a shaft according to the text?

    <p>$2pNT/60$</p> Signup and view all the answers

    What does the torsion equation represent?

    <p>Torque from twisting force</p> Signup and view all the answers

    Why is the turning moment diagram plotted for a single cylinder double-acting steam engine?

    <p>To study piston effort and crank-effort for different crank positions</p> Signup and view all the answers

    When is the turning moment zero in a single cylinder double-acting steam engine?

    <p>At 180° crank angle</p> Signup and view all the answers

    What does a negative turning moment signify in an engine according to the text?

    <p>Retardation</p> Signup and view all the answers

    'Accelerating torque on the rotating parts of the engine' is calculated as:

    <p>$T - Tmean$</p> Signup and view all the answers

    'Flywheel accelerates' when:

    <p>$T - Tmean$ is positive</p> Signup and view all the answers

    What type of engine has a turning moment diagram shown after two revolutions of the crankshaft?

    <p>Four stroke cycle internal combustion engine</p> Signup and view all the answers

    What does the coefficient of fluctuation of energy represent?

    <p>The ratio of maximum energy to minimum energy</p> Signup and view all the answers

    How is the mean torque calculated in terms of the angle turned in one revolution for a four-stroke internal combustion engine?

    <p>$T_{mean} = 4π$</p> Signup and view all the answers

    What does the maximum fluctuation of energy equal to?

    <p>$a_2 - a_3 + a_4$</p> Signup and view all the answers

    What represents the maximum energy in the flywheel?

    <p>$E + a$</p> Signup and view all the answers

    What is the cycle repeat point after which energy at G equals energy at A?

    <p>G</p> Signup and view all the answers

    Which engine type has an angle turned of $2π$ in one revolution?

    <p>Two-stroke internal combustion engine</p> Signup and view all the answers

    What is the formula for net load on the brake in a rope brake system?

    <p>(W - S) N</p> Signup and view all the answers

    In an epicyclic-train dynamometer, what is equal to the tangential effort exerted by the spur gear on the pinion?

    <p>Tangential reaction of the annular gear on the pinion</p> Signup and view all the answers

    What is used to balance the total upward force on the lever in an epicyclic-train dynamometer?

    <p>Dead weight W</p> Signup and view all the answers

    What is the formula for torque transmitted in an epicyclic-train dynamometer?

    <p>$T = P \cdot R$</p> Signup and view all the answers

    In a belt transmission dynamometer, what causes movement about the pivot E?

    <p>Difference in belt tension</p> Signup and view all the answers

    What is used to balance the movement about pivot E in a belt transmission dynamometer?

    <p>Dead weight W</p> Signup and view all the answers

    In a belt transmission dynamometer, what are pulleys C and D connected by?

    <p>Continuous belt</p> Signup and view all the answers

    What is used to measure the difference between the tensions of the belt in a belt transmission dynamometer?

    <p>$2T1$</p> Signup and view all the answers

    What causes the clutch plate and the driven shaft to rotate?

    <p>Friction between the linings on the clutch plate</p> Signup and view all the answers

    When does clutch slip occur?

    <p>When the resisting torque on the drive shaft exceeds the torque at the clutch</p> Signup and view all the answers

    What is the purpose of using a multi-plate clutch?

    <p>To increase the capacity of the clutch to transmit torque</p> Signup and view all the answers

    What happens when the actuating force on the pedal is removed in a multi-plate clutch?

    <p>A spring presses the discs into contact with the friction rings</p> Signup and view all the answers

    What is considered when pressure is uniformly distributed over the entire area of a friction face?

    <p>Normal intensity of pressure</p> Signup and view all the answers

    What does 'R' represent in the total frictional torque equation for a multi-plate clutch?

    <p>Mean radius of the friction surfaces</p> Signup and view all the answers

    How is 'p' related to 'r' in a case of uniform wear?

    <p>'p' is inversely proportional to 'r'</p> Signup and view all the answers

    What happens to a multi-plate clutch when there are more friction rings and metal plates?

    <p>The capacity to transmit torque increases</p> Signup and view all the answers

    What causes a spring in a multi-plate clutch to press discs into contact with friction rings?

    <p>Actuating force from the pedal</p> Signup and view all the answers

    Study Notes

    Transmission Dynamometers

    • Classification of transmission dynamometers:
      • Epicyclic-train dynamometer
      • Belt transmission dynamometer (also known as Froude or Throneycroft transmission dynamometer)
      • Torsion dynamometer

    Epicyclic-train Dynamometer

    • Consists of a simple epicyclic train of gears:
      • Spur gear
      • Annular gear (with internal teeth)
      • Pinion (intermediate gear)
    • Pinion revolves freely on a lever pivoted to the common axis of the driving and driven shafts
    • Weight (w) is placed at the smaller end of the lever to keep it in position
    • Tangential effort (P) exerted by the spur gear on the pinion is equal to the tangential reaction of the annular gear on the pinion
    • Total upward force on the lever acting through the axis of the pinion is 2P
    • Balanced by a dead weight (W) at the end of the lever

    Belt Transmission Dynamometer

    • Measures the difference between the tensions of the tight and slack sides of the belt
    • Consists of a pulley (A) rigidly fixed to the shaft of an engine, and another pulley (B) mounted on another shaft
    • Pulleys are connected by a continuous belt passing round two loose pulleys (C and D) mounted on a T-shaped frame
    • Frame is pivoted at E and its movement is controlled by two stops (S, S)
    • Tension in the tight side of the belt (T1) is greater than the tension in the slack side of the belt (T2)

    Friction Clutches

    • Types of friction clutches:
      • Single plate clutch (also known as disc clutch)
      • Cone clutch
    • Single plate clutch:
      • Consists of a clutch plate attached to a splined hub which is free to slide axially on splines cut on the driven shaft
      • Clutch plate is made of steel and has a ring of friction lining on each side
      • Engine shaft supports a rigidly fixed flywheel
      • Spring-loaded pressure plate presses the clutch plate firmly against the flywheel when the clutch is engaged
    • Cone clutch:
      • Consists of one pair of friction surface only
      • Driver is keyed to the driving shaft by a sunk key and has an inside conical surface or face which exactly fits into the outside conical surface of the driven
      • Driven member resting on the feather key in the driven shaft may be shifted along the shaft by a forked lever provided at B, in order to engage the clutch by bringing the two conical surfaces in contact

    Centrifugal Clutch

    • Consists of a number of shoes on the inside of a rim of the pulley
    • Shoes are covered with a friction material
    • Shoes can move radially in guides and are held against the boss (or spider) on the driving shaft by means of springs
    • Centrifugal force acting on each shoe at the running speed is proportional to the mass of the shoe and the square of the angular running speed
    • Frictional torque acting on each shoe is proportional to the coefficient of friction and the radius of the pulley

    Problems and Examples

    • Examples of problems and solutions related to brake power, transmission dynamometers, friction clutches, and centrifugal clutches
    • Solutions involve calculations of torque, power, and axial load acting on the clutch or brake### Centrifugal Clutch
    • A centrifugal clutch is a type of clutch that uses centrifugal force to engage and disengage the clutch.
    • The clutch consists of a spider, shoes, and a pressure plate.
    • At engagement speed, the shoes move outward and contact the pressure plate, engaging the clutch.
    • The frictional force acting tangentially on each shoe is calculated using the formula: F = (Pc - Ps)
    • The torque transmitted (T) is calculated using the formula: T = n.F.R

    Dynamometers

    • A dynamometer is a device that measures the torque and power output of an engine.
    • Types of dynamometers: absorption dynamometers and transmission dynamometers.
    • Absorption dynamometers absorb the energy produced by the engine and convert it into heat.
    • Transmission dynamometers transmit the energy produced by the engine to another machine, where it is measured.

    Prony Brake Dynamometer

    • A Prony brake dynamometer is a type of absorption dynamometer.
    • It consists of two wooden blocks placed around a pulley fixed to the engine shaft.
    • The blocks are clamped by means of two bolts and nuts.
    • A helical spring is provided between the nut and the upper block to adjust the pressure on the pulley.
    • The upper block has a long lever attached to it, which carries a weight at its outer end.

    Rope Brake Dynamometer

    • A rope brake dynamometer is another type of absorption dynamometer.
    • It consists of one or more ropes wound around a flywheel or pulley fixed to the engine shaft.
    • The upper end of the ropes is attached to a spring balance, while the lower end is kept in position by applying a dead weight.
    • Wooden blocks are placed at intervals around the circumference of the flywheel to prevent the rope from slipping.

    Torsion Dynamometer

    • A torsion dynamometer is used to measure large powers, particularly in turbine or motor vessels.
    • It measures the twist of the shaft, which is proportional to the torque acting on the shaft.
    • The power transmitted (P) is calculated using the formula: P = 2πNT/60

    Turning Moment and Flywheel

    • The turning moment diagram is a graphical representation of the turning moment or crank-effort for various positions of the crank.
    • It is plotted on cartesian coordinates, with the turning moment as the ordinate and crank angle as the abscissa.
    • The turning moment diagram for a single cylinder double acting steam engine shows that the turning moment is zero when the crank angle is zero, maximum when the crank angle is 90°, and again zero when the crank angle is 180°.

    Turning Moment Diagram for a Four Stroke Cycle Internal Combustion Engine

    • The turning moment diagram for a four stroke cycle internal combustion engine shows that there is one working stroke after the crank has turned through two revolutions.
    • The turning moment diagram for a multi-cylinder engine shows that the fluctuation of energy is reduced with the increase in the number of cylinders.

    Coefficient of Fluctuation of Energy

    • The coefficient of fluctuation of energy is defined as the ratio of the maximum fluctuation of energy to the work done per cycle.
    • It is calculated using the formula: coefficient of fluctuation of energy = maximum fluctuation of energy / work done per cycle

    Plate and Disc Clutch

    • A plate and disc clutch is a type of clutch that uses frictional forces to transmit torque.
    • The torque transmitted (T) is calculated using the formula: T = µ.W.R
    • The mean radius of the friction surfaces (R) is calculated using the formula: R = (r1 + r2)/2
    • In a multi-plate clutch, the number of frictional linings and metal plates is increased, which increases the capacity of the clutch to transmit torque.

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    Description

    Learn about friction clutches and the functionality of a single plate clutch (disc clutch) in transmitting rotary motion between two shafts. Discover how friction is utilized to connect the engine shaft to the gear box shaft effectively.

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