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Questions and Answers
What was the main purpose of developing independent front suspension in the 1930s?
What type of spring is commonly used in independent front suspension?
What is the advantage of independent front suspension in terms of wheel movement?
What is the effect of independent front suspension on wheel wobble?
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What is the advantage of independent front suspension in terms of steering conditions?
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Which of the following is NOT a type of independent front suspension?
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Which type of suspension is used in all vehicles nowadays?
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What is the effect of independent front suspension on the front wheels?
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What is the advantage of independent front suspension in terms of road conditions?
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How many types of independent front suspension are mentioned in the content?
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What is the primary benefit of using independent front suspension in vehicles?
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Which type of spring is used in longitudinal suspension?
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What is the effect of a wider spacing of the front springs on steering conditions?
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How do the front wheels respond to road conditions in an independent front suspension system?
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What is the function of a coil or torsion bar or leaf spring in an independent front suspension system?
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Which type of independent front suspension system is characterized by a sliding motion?
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What is the primary difference between a longitudinal suspension and a transverse suspension?
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Which of the following is a type of independent front suspension system?
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What is the primary advantage of using a Mac Pherson Strut and link type suspension?
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Which type of suspension system is commonly used in modern vehicles?
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What is the primary benefit of using independent front suspension in vehicles?
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What is the characteristic of independent front suspension system?
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What is the effect of independent front suspension on vehicle steering?
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Which type of suspension system is used in modern vehicles?
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What is the function of coil or torsion bar or leaf spring in independent front suspension?
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What is the advantage of independent front suspension in terms of wheel movement?
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How do the front wheels respond to road conditions in an independent front suspension system?
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What is the characteristic of longitudinal leaf spring rear suspension?
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How many types of independent front suspensions are mentioned in the content?
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What is the primary advantage of using a coil spring in independent front suspension?
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What is the primary benefit of independent front suspension in terms of vehicle performance?
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Which of the following is a characteristic of independent front suspension?
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What is the purpose of a coil or torsion bar or leaf spring in independent front suspension?
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Which of the following types of independent front suspension uses a sliding motion?
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What is the effect of a wider spacing of the front springs on the steering system?
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Which type of independent front suspension uses a combination of a coil spring and a link?
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What is the primary difference between longitudinal and transverse suspensions?
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Which type of suspension is most commonly used in modern vehicles?
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What is the effect of independent front suspension on the vehicle's response to road conditions?
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What is the characteristic of independent front suspension that improves vehicle stability?
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Study Notes
Transmission System
- The transmission system plays a crucial role in transferring power from the engine to the wheels, enabling the vehicle to move efficiently across different speeds and conditions.
- Components of a transmission system:
- Transmission (manual or automatic)
- Clutch (for manual transmission)
- Gearbox
- Differential
- Driveshaft (propeller shaft)
- Torque converter (for automatic transmission)
Functions of a Transmission System
- Gear ratio selection
- Torque multiplication
- Smooth power delivery
- Adaptability to driving conditions
- Efficiency improvement (modern transmission systems aim to optimize fuel efficiency and reduce emissions)
Clutches and Power Transmission
- The purpose of the clutch is to allow the driver to couple or decouple the engine and transmission.
- Requirements of a clutch:
- Pick up its load smoothly without grab or clatter
- Have a driven disc of low moment of inertia to permit easy shifting
- Damp out any vibration of the crankshaft to prevent gear clatter
- Require little pedal pressure to operate
- Be easy to adjust and service
- Be cheap to manufacture
Types of Clutches
- Positive clutches
- Merits: simple, no slip, no heat generated, compact, and low cost
- Friction clutches
- Merits: smooth engagement, can slip during engagement, high torque capacity
- Types:
- Single plate clutch
- Multi-plate clutch
- Centrifugal clutch
- Semi-centrifugal clutch
- Diaphragm spring single plate clutch
- Electro-magnetic clutch
- Overrunning clutch or free-wheel unit
Diaphragm Spring Single Plate Clutch
- Advantages:
- Compact design
- Easier to balance rotationally
- Uniformly distributed pressure on pressure plate
- No release levers required
- Minimum effort required to disengage the clutch
- Minimum internal friction
Multi-Plate Clutch
- Used in heavy transport vehicles, epicyclic gearboxes, and racing cars
- Advantages:
- Higher torque transmission capacity
- Compact design
Automatic Clutch
- Centrifugal clutch: automatically disengages when speed falls below a certain value and re-engages when speed rises above it
- Fluid coupling or fluid torque converter: used to transmit power between two rotating shafts without Interrupting the flow of power
Gear Box in an Automobile
- Necessity of gear box: to maintain engine speed at the most economical value under all conditions of vehicle movement
- Functions of a gear box:
- Torque ratio variation between engine and wheels
- Means of reversal of vehicle motion
- Transmission can be disconnected from engine by neutral position of gear box
Types of Gear Box
- Progressive type gear box
- Epicyclic (or) planetary type gear box
- Selective type gear box (e.g., constant mesh gear box with positive dog clutch, constant mesh gear box with synchromesh device, sliding mesh gear box)### Gearbox
- A gearbox is a mechanical device that uses gears to transmit and change the speed of rotation of a mechanical shaft
- Types of gearboxes:
- Constant mesh gearbox
- Synchromesh gearbox
- Automatic gearbox
Constant Mesh Gearbox
- All gears on the main shaft are in constant mesh with the corresponding gears on the lay shaft
- Gears on the lay shaft are fixed, while those on the main shaft are free to rotate
- Dog clutches are used to engage and disengage gears
Synchromesh Gearbox
- Similar to constant mesh gearbox, but with synchronizers instead of dog clutches
- Synchronizers allow for smooth gear changes by equalizing the speed of the gears before engagement
- Used in modern cars to reduce the cost of production
Automatic Gearbox
- Also known as automatic transmission
- Uses a complex system of gears, clutches, and hydraulic pumps to change gear ratios automatically
- Components:
- Torque converter
- Planetary gear sets
- Hydraulic system
- Control unit (TCU or TCM)
- Working:
- The TCU receives inputs from sensors and determines the appropriate gear ratio
- Hydraulic pressure is used to engage and disengage clutches and brake bands
- Shift points are determined by factors such as vehicle speed, engine load, and driver demand
Differential
- A mechanical device that allows each of the driving wheels to rotate at different speeds
- Purpose:
- To drive a pair of wheels with equal torque while allowing them to rotate at different speeds
- To prevent wheel spinning and road damage when turning
- Components:
- Pinion drive gear
- Crown wheel/ring gear
- Spider/planet gear
- Cross-pin
- Side/sun gear
- Differential case assembly
- Construction:
- The differential is an arrangement of gears that work together to allow the vehicle to take a turn smoothly
- The pinion gear is fixed to the propeller shaft and rotates the crown wheel
Suspension System
- The chassis of the vehicle is connected to the front and rear wheels through the medium of springs, shock absorbers, and axles
- Components:
- Springs
- Dampers (shock absorbers)
- Stabilizer (sway bar or anti-roll bar)
- Linkage system
- Functions:
- To eliminate road shocks from transmission to vehicle components
- To obtain good road holding while driving, cornering, and braking
- To keep the proper steering geometry
- To obtain a particular height to body structure
- To resist the torque and braking reactions
- To maintain the stability of the vehicle while traveling over rough roads
- To safeguard the occupants against road shocks and provide a riding comfort
Sprung Weight and Unsprung Weight
- Sprung weight: The weight of the vehicle body that is supported by springs
- Unsprung weight: The weight of the wheels, axles, and other parts of the vehicle that are not supported by springs
- Effects of unsprung weight:
- Controls the trade-off between wheel bump and vibration isolation
- Affects the ride quality and road noise
- Exacerbates wheel control issues under hard acceleration or braking### Types of Springs
- There are five types of springs: compression, compression-shear, steel reinforced, progressive, and face shear springs.
- Air springs are also used in air suspension systems, which can be adjusted up or down by supplying air pressure.
Leaf Spring Suspension
- Leaf spring suspension consists of a number of leaves of increasing lengths made of steel plates.
- The spring eye is mounted to the frame by a pin called shackle pin.
- The centre portion of the spring is attached to the front axle by a V-bolt.
- The stiffness or spring rate of the leaf spring is determined by its length, width, and thickness.
- Greater the number of leaves, higher the stiffness.
Air Suspension System
- Air springs are flexible bellows made of textile-reinforced rubber, containing compressed air.
- They are used to carry load on vehicles and provide elasticity or "springiness" when compressed.
- Air springs have three characteristics: they are soft when unloaded, they increase stiffness when loaded, and they maintain constant vehicle height.
- They provide optimum riding comfort in both lightly loaded and fully loaded conditions.
Shock Absorber
- Shock absorbers are used to control vibrations on springs, provide comfortable ride, and act flexible and rigid.
- They are used as a part of the suspension system and provide more resistance to the motion of the spring and road wheel.
- Types of shock absorbers include mechanical, hydraulic, and telescopic shock absorbers.
Telescopic Shock Absorber
- Construction consists of an upper eye attached to the axle, a lower eye attached to the chassis frame, and two-way valves.
- Working involves fluid flowing between the valves to produce a damping force.
- The damping force varies with the speed of the piston.
Types of Suspension System
- There are two basic types of suspension systems: front end suspension and rear end suspension.
- Front end suspension types include independent front suspension and rigid axle front suspension.
- Rear end suspension types include longitudinal leaf spring, transverse leaf spring, and coil spring rear end suspension.
Independent Front Suspension
- Developed in the 1930s to improve vehicle ride control and riding comfort.
- Each front wheel is mounted on its own axle and independently supported by a coil or torsion bar or leaf spring.
- Types of independent front suspensions include longitudinal, transverse, sliding, MacPherson Strut, parallelogram, trailing link, and vertical guide suspensions.
Transmission System
- The transmission system plays a crucial role in transferring power from the engine to the wheels, enabling the vehicle to move efficiently across different speeds and conditions.
- Components of a transmission system:
- Transmission (manual or automatic)
- Clutch (for manual transmission)
- Gearbox
- Differential
- Driveshaft (propeller shaft)
- Torque converter (for automatic transmission)
Functions of a Transmission System
- Gear ratio selection
- Torque multiplication
- Smooth power delivery
- Adaptability to driving conditions
- Efficiency improvement (modern transmission systems aim to optimize fuel efficiency and reduce emissions)
Clutches and Power Transmission
- The purpose of the clutch is to allow the driver to couple or decouple the engine and transmission.
- Requirements of a clutch:
- Pick up its load smoothly without grab or clatter
- Have a driven disc of low moment of inertia to permit easy shifting
- Damp out any vibration of the crankshaft to prevent gear clatter
- Require little pedal pressure to operate
- Be easy to adjust and service
- Be cheap to manufacture
Types of Clutches
- Positive clutches
- Merits: simple, no slip, no heat generated, compact, and low cost
- Friction clutches
- Merits: smooth engagement, can slip during engagement, high torque capacity
- Types:
- Single plate clutch
- Multi-plate clutch
- Centrifugal clutch
- Semi-centrifugal clutch
- Diaphragm spring single plate clutch
- Electro-magnetic clutch
- Overrunning clutch or free-wheel unit
Diaphragm Spring Single Plate Clutch
- Advantages:
- Compact design
- Easier to balance rotationally
- Uniformly distributed pressure on pressure plate
- No release levers required
- Minimum effort required to disengage the clutch
- Minimum internal friction
Multi-Plate Clutch
- Used in heavy transport vehicles, epicyclic gearboxes, and racing cars
- Advantages:
- Higher torque transmission capacity
- Compact design
Automatic Clutch
- Centrifugal clutch: automatically disengages when speed falls below a certain value and re-engages when speed rises above it
- Fluid coupling or fluid torque converter: used to transmit power between two rotating shafts without Interrupting the flow of power
Gear Box in an Automobile
- Necessity of gear box: to maintain engine speed at the most economical value under all conditions of vehicle movement
- Functions of a gear box:
- Torque ratio variation between engine and wheels
- Means of reversal of vehicle motion
- Transmission can be disconnected from engine by neutral position of gear box
Types of Gear Box
- Progressive type gear box
- Epicyclic (or) planetary type gear box
- Selective type gear box (e.g., constant mesh gear box with positive dog clutch, constant mesh gear box with synchromesh device, sliding mesh gear box)### Gearbox
- A gearbox is a mechanical device that uses gears to transmit and change the speed of rotation of a mechanical shaft
- Types of gearboxes:
- Constant mesh gearbox
- Synchromesh gearbox
- Automatic gearbox
Constant Mesh Gearbox
- All gears on the main shaft are in constant mesh with the corresponding gears on the lay shaft
- Gears on the lay shaft are fixed, while those on the main shaft are free to rotate
- Dog clutches are used to engage and disengage gears
Synchromesh Gearbox
- Similar to constant mesh gearbox, but with synchronizers instead of dog clutches
- Synchronizers allow for smooth gear changes by equalizing the speed of the gears before engagement
- Used in modern cars to reduce the cost of production
Automatic Gearbox
- Also known as automatic transmission
- Uses a complex system of gears, clutches, and hydraulic pumps to change gear ratios automatically
- Components:
- Torque converter
- Planetary gear sets
- Hydraulic system
- Control unit (TCU or TCM)
- Working:
- The TCU receives inputs from sensors and determines the appropriate gear ratio
- Hydraulic pressure is used to engage and disengage clutches and brake bands
- Shift points are determined by factors such as vehicle speed, engine load, and driver demand
Differential
- A mechanical device that allows each of the driving wheels to rotate at different speeds
- Purpose:
- To drive a pair of wheels with equal torque while allowing them to rotate at different speeds
- To prevent wheel spinning and road damage when turning
- Components:
- Pinion drive gear
- Crown wheel/ring gear
- Spider/planet gear
- Cross-pin
- Side/sun gear
- Differential case assembly
- Construction:
- The differential is an arrangement of gears that work together to allow the vehicle to take a turn smoothly
- The pinion gear is fixed to the propeller shaft and rotates the crown wheel
Suspension System
- The chassis of the vehicle is connected to the front and rear wheels through the medium of springs, shock absorbers, and axles
- Components:
- Springs
- Dampers (shock absorbers)
- Stabilizer (sway bar or anti-roll bar)
- Linkage system
- Functions:
- To eliminate road shocks from transmission to vehicle components
- To obtain good road holding while driving, cornering, and braking
- To keep the proper steering geometry
- To obtain a particular height to body structure
- To resist the torque and braking reactions
- To maintain the stability of the vehicle while traveling over rough roads
- To safeguard the occupants against road shocks and provide a riding comfort
Sprung Weight and Unsprung Weight
- Sprung weight: The weight of the vehicle body that is supported by springs
- Unsprung weight: The weight of the wheels, axles, and other parts of the vehicle that are not supported by springs
- Effects of unsprung weight:
- Controls the trade-off between wheel bump and vibration isolation
- Affects the ride quality and road noise
- Exacerbates wheel control issues under hard acceleration or braking### Types of Springs
- There are five types of springs: compression, compression-shear, steel reinforced, progressive, and face shear springs.
- Air springs are also used in air suspension systems, which can be adjusted up or down by supplying air pressure.
Leaf Spring Suspension
- Leaf spring suspension consists of a number of leaves of increasing lengths made of steel plates.
- The spring eye is mounted to the frame by a pin called shackle pin.
- The centre portion of the spring is attached to the front axle by a V-bolt.
- The stiffness or spring rate of the leaf spring is determined by its length, width, and thickness.
- Greater the number of leaves, higher the stiffness.
Air Suspension System
- Air springs are flexible bellows made of textile-reinforced rubber, containing compressed air.
- They are used to carry load on vehicles and provide elasticity or "springiness" when compressed.
- Air springs have three characteristics: they are soft when unloaded, they increase stiffness when loaded, and they maintain constant vehicle height.
- They provide optimum riding comfort in both lightly loaded and fully loaded conditions.
Shock Absorber
- Shock absorbers are used to control vibrations on springs, provide comfortable ride, and act flexible and rigid.
- They are used as a part of the suspension system and provide more resistance to the motion of the spring and road wheel.
- Types of shock absorbers include mechanical, hydraulic, and telescopic shock absorbers.
Telescopic Shock Absorber
- Construction consists of an upper eye attached to the axle, a lower eye attached to the chassis frame, and two-way valves.
- Working involves fluid flowing between the valves to produce a damping force.
- The damping force varies with the speed of the piston.
Types of Suspension System
- There are two basic types of suspension systems: front end suspension and rear end suspension.
- Front end suspension types include independent front suspension and rigid axle front suspension.
- Rear end suspension types include longitudinal leaf spring, transverse leaf spring, and coil spring rear end suspension.
Independent Front Suspension
- Developed in the 1930s to improve vehicle ride control and riding comfort.
- Each front wheel is mounted on its own axle and independently supported by a coil or torsion bar or leaf spring.
- Types of independent front suspensions include longitudinal, transverse, sliding, MacPherson Strut, parallelogram, trailing link, and vertical guide suspensions.
Transmission System
- The transmission system plays a crucial role in transferring power from the engine to the wheels, enabling the vehicle to move efficiently across different speeds and conditions.
- Components of a transmission system:
- Transmission (manual or automatic)
- Clutch (for manual transmission)
- Gearbox
- Differential
- Driveshaft (propeller shaft)
- Torque converter (for automatic transmission)
Functions of a Transmission System
- Gear ratio selection
- Torque multiplication
- Smooth power delivery
- Adaptability to driving conditions
- Efficiency improvement (modern transmission systems aim to optimize fuel efficiency and reduce emissions)
Clutches and Power Transmission
- The purpose of the clutch is to allow the driver to couple or decouple the engine and transmission.
- Requirements of a clutch:
- Pick up its load smoothly without grab or clatter
- Have a driven disc of low moment of inertia to permit easy shifting
- Damp out any vibration of the crankshaft to prevent gear clatter
- Require little pedal pressure to operate
- Be easy to adjust and service
- Be cheap to manufacture
Types of Clutches
- Positive clutches
- Merits: simple, no slip, no heat generated, compact, and low cost
- Friction clutches
- Merits: smooth engagement, can slip during engagement, high torque capacity
- Types:
- Single plate clutch
- Multi-plate clutch
- Centrifugal clutch
- Semi-centrifugal clutch
- Diaphragm spring single plate clutch
- Electro-magnetic clutch
- Overrunning clutch or free-wheel unit
Diaphragm Spring Single Plate Clutch
- Advantages:
- Compact design
- Easier to balance rotationally
- Uniformly distributed pressure on pressure plate
- No release levers required
- Minimum effort required to disengage the clutch
- Minimum internal friction
Multi-Plate Clutch
- Used in heavy transport vehicles, epicyclic gearboxes, and racing cars
- Advantages:
- Higher torque transmission capacity
- Compact design
Automatic Clutch
- Centrifugal clutch: automatically disengages when speed falls below a certain value and re-engages when speed rises above it
- Fluid coupling or fluid torque converter: used to transmit power between two rotating shafts without Interrupting the flow of power
Gear Box in an Automobile
- Necessity of gear box: to maintain engine speed at the most economical value under all conditions of vehicle movement
- Functions of a gear box:
- Torque ratio variation between engine and wheels
- Means of reversal of vehicle motion
- Transmission can be disconnected from engine by neutral position of gear box
Types of Gear Box
- Progressive type gear box
- Epicyclic (or) planetary type gear box
- Selective type gear box (e.g., constant mesh gear box with positive dog clutch, constant mesh gear box with synchromesh device, sliding mesh gear box)### Gearbox
- A gearbox is a mechanical device that uses gears to transmit and change the speed of rotation of a mechanical shaft
- Types of gearboxes:
- Constant mesh gearbox
- Synchromesh gearbox
- Automatic gearbox
Constant Mesh Gearbox
- All gears on the main shaft are in constant mesh with the corresponding gears on the lay shaft
- Gears on the lay shaft are fixed, while those on the main shaft are free to rotate
- Dog clutches are used to engage and disengage gears
Synchromesh Gearbox
- Similar to constant mesh gearbox, but with synchronizers instead of dog clutches
- Synchronizers allow for smooth gear changes by equalizing the speed of the gears before engagement
- Used in modern cars to reduce the cost of production
Automatic Gearbox
- Also known as automatic transmission
- Uses a complex system of gears, clutches, and hydraulic pumps to change gear ratios automatically
- Components:
- Torque converter
- Planetary gear sets
- Hydraulic system
- Control unit (TCU or TCM)
- Working:
- The TCU receives inputs from sensors and determines the appropriate gear ratio
- Hydraulic pressure is used to engage and disengage clutches and brake bands
- Shift points are determined by factors such as vehicle speed, engine load, and driver demand
Differential
- A mechanical device that allows each of the driving wheels to rotate at different speeds
- Purpose:
- To drive a pair of wheels with equal torque while allowing them to rotate at different speeds
- To prevent wheel spinning and road damage when turning
- Components:
- Pinion drive gear
- Crown wheel/ring gear
- Spider/planet gear
- Cross-pin
- Side/sun gear
- Differential case assembly
- Construction:
- The differential is an arrangement of gears that work together to allow the vehicle to take a turn smoothly
- The pinion gear is fixed to the propeller shaft and rotates the crown wheel
Suspension System
- The chassis of the vehicle is connected to the front and rear wheels through the medium of springs, shock absorbers, and axles
- Components:
- Springs
- Dampers (shock absorbers)
- Stabilizer (sway bar or anti-roll bar)
- Linkage system
- Functions:
- To eliminate road shocks from transmission to vehicle components
- To obtain good road holding while driving, cornering, and braking
- To keep the proper steering geometry
- To obtain a particular height to body structure
- To resist the torque and braking reactions
- To maintain the stability of the vehicle while traveling over rough roads
- To safeguard the occupants against road shocks and provide a riding comfort
Sprung Weight and Unsprung Weight
- Sprung weight: The weight of the vehicle body that is supported by springs
- Unsprung weight: The weight of the wheels, axles, and other parts of the vehicle that are not supported by springs
- Effects of unsprung weight:
- Controls the trade-off between wheel bump and vibration isolation
- Affects the ride quality and road noise
- Exacerbates wheel control issues under hard acceleration or braking### Types of Springs
- There are five types of springs: compression, compression-shear, steel reinforced, progressive, and face shear springs.
- Air springs are also used in air suspension systems, which can be adjusted up or down by supplying air pressure.
Leaf Spring Suspension
- Leaf spring suspension consists of a number of leaves of increasing lengths made of steel plates.
- The spring eye is mounted to the frame by a pin called shackle pin.
- The centre portion of the spring is attached to the front axle by a V-bolt.
- The stiffness or spring rate of the leaf spring is determined by its length, width, and thickness.
- Greater the number of leaves, higher the stiffness.
Air Suspension System
- Air springs are flexible bellows made of textile-reinforced rubber, containing compressed air.
- They are used to carry load on vehicles and provide elasticity or "springiness" when compressed.
- Air springs have three characteristics: they are soft when unloaded, they increase stiffness when loaded, and they maintain constant vehicle height.
- They provide optimum riding comfort in both lightly loaded and fully loaded conditions.
Shock Absorber
- Shock absorbers are used to control vibrations on springs, provide comfortable ride, and act flexible and rigid.
- They are used as a part of the suspension system and provide more resistance to the motion of the spring and road wheel.
- Types of shock absorbers include mechanical, hydraulic, and telescopic shock absorbers.
Telescopic Shock Absorber
- Construction consists of an upper eye attached to the axle, a lower eye attached to the chassis frame, and two-way valves.
- Working involves fluid flowing between the valves to produce a damping force.
- The damping force varies with the speed of the piston.
Types of Suspension System
- There are two basic types of suspension systems: front end suspension and rear end suspension.
- Front end suspension types include independent front suspension and rigid axle front suspension.
- Rear end suspension types include longitudinal leaf spring, transverse leaf spring, and coil spring rear end suspension.
Independent Front Suspension
- Developed in the 1930s to improve vehicle ride control and riding comfort.
- Each front wheel is mounted on its own axle and independently supported by a coil or torsion bar or leaf spring.
- Types of independent front suspensions include longitudinal, transverse, sliding, MacPherson Strut, parallelogram, trailing link, and vertical guide suspensions.
Transmission System
- The transmission system plays a crucial role in transferring power from the engine to the wheels, enabling the vehicle to move efficiently across different speeds and conditions.
- Components of a transmission system:
- Transmission (manual or automatic)
- Clutch (for manual transmission)
- Gearbox
- Differential
- Driveshaft (propeller shaft)
- Torque converter (for automatic transmission)
Functions of a Transmission System
- Gear ratio selection
- Torque multiplication
- Smooth power delivery
- Adaptability to driving conditions
- Efficiency improvement (modern transmission systems aim to optimize fuel efficiency and reduce emissions)
Clutches and Power Transmission
- The purpose of the clutch is to allow the driver to couple or decouple the engine and transmission.
- Requirements of a clutch:
- Pick up its load smoothly without grab or clatter
- Have a driven disc of low moment of inertia to permit easy shifting
- Damp out any vibration of the crankshaft to prevent gear clatter
- Require little pedal pressure to operate
- Be easy to adjust and service
- Be cheap to manufacture
Types of Clutches
- Positive clutches
- Merits: simple, no slip, no heat generated, compact, and low cost
- Friction clutches
- Merits: smooth engagement, can slip during engagement, high torque capacity
- Types:
- Single plate clutch
- Multi-plate clutch
- Centrifugal clutch
- Semi-centrifugal clutch
- Diaphragm spring single plate clutch
- Electro-magnetic clutch
- Overrunning clutch or free-wheel unit
Diaphragm Spring Single Plate Clutch
- Advantages:
- Compact design
- Easier to balance rotationally
- Uniformly distributed pressure on pressure plate
- No release levers required
- Minimum effort required to disengage the clutch
- Minimum internal friction
Multi-Plate Clutch
- Used in heavy transport vehicles, epicyclic gearboxes, and racing cars
- Advantages:
- Higher torque transmission capacity
- Compact design
Automatic Clutch
- Centrifugal clutch: automatically disengages when speed falls below a certain value and re-engages when speed rises above it
- Fluid coupling or fluid torque converter: used to transmit power between two rotating shafts without Interrupting the flow of power
Gear Box in an Automobile
- Necessity of gear box: to maintain engine speed at the most economical value under all conditions of vehicle movement
- Functions of a gear box:
- Torque ratio variation between engine and wheels
- Means of reversal of vehicle motion
- Transmission can be disconnected from engine by neutral position of gear box
Types of Gear Box
- Progressive type gear box
- Epicyclic (or) planetary type gear box
- Selective type gear box (e.g., constant mesh gear box with positive dog clutch, constant mesh gear box with synchromesh device, sliding mesh gear box)### Gearbox
- A gearbox is a mechanical device that uses gears to transmit and change the speed of rotation of a mechanical shaft
- Types of gearboxes:
- Constant mesh gearbox
- Synchromesh gearbox
- Automatic gearbox
Constant Mesh Gearbox
- All gears on the main shaft are in constant mesh with the corresponding gears on the lay shaft
- Gears on the lay shaft are fixed, while those on the main shaft are free to rotate
- Dog clutches are used to engage and disengage gears
Synchromesh Gearbox
- Similar to constant mesh gearbox, but with synchronizers instead of dog clutches
- Synchronizers allow for smooth gear changes by equalizing the speed of the gears before engagement
- Used in modern cars to reduce the cost of production
Automatic Gearbox
- Also known as automatic transmission
- Uses a complex system of gears, clutches, and hydraulic pumps to change gear ratios automatically
- Components:
- Torque converter
- Planetary gear sets
- Hydraulic system
- Control unit (TCU or TCM)
- Working:
- The TCU receives inputs from sensors and determines the appropriate gear ratio
- Hydraulic pressure is used to engage and disengage clutches and brake bands
- Shift points are determined by factors such as vehicle speed, engine load, and driver demand
Differential
- A mechanical device that allows each of the driving wheels to rotate at different speeds
- Purpose:
- To drive a pair of wheels with equal torque while allowing them to rotate at different speeds
- To prevent wheel spinning and road damage when turning
- Components:
- Pinion drive gear
- Crown wheel/ring gear
- Spider/planet gear
- Cross-pin
- Side/sun gear
- Differential case assembly
- Construction:
- The differential is an arrangement of gears that work together to allow the vehicle to take a turn smoothly
- The pinion gear is fixed to the propeller shaft and rotates the crown wheel
Suspension System
- The chassis of the vehicle is connected to the front and rear wheels through the medium of springs, shock absorbers, and axles
- Components:
- Springs
- Dampers (shock absorbers)
- Stabilizer (sway bar or anti-roll bar)
- Linkage system
- Functions:
- To eliminate road shocks from transmission to vehicle components
- To obtain good road holding while driving, cornering, and braking
- To keep the proper steering geometry
- To obtain a particular height to body structure
- To resist the torque and braking reactions
- To maintain the stability of the vehicle while traveling over rough roads
- To safeguard the occupants against road shocks and provide a riding comfort
Sprung Weight and Unsprung Weight
- Sprung weight: The weight of the vehicle body that is supported by springs
- Unsprung weight: The weight of the wheels, axles, and other parts of the vehicle that are not supported by springs
- Effects of unsprung weight:
- Controls the trade-off between wheel bump and vibration isolation
- Affects the ride quality and road noise
- Exacerbates wheel control issues under hard acceleration or braking### Types of Springs
- There are five types of springs: compression, compression-shear, steel reinforced, progressive, and face shear springs.
- Air springs are also used in air suspension systems, which can be adjusted up or down by supplying air pressure.
Leaf Spring Suspension
- Leaf spring suspension consists of a number of leaves of increasing lengths made of steel plates.
- The spring eye is mounted to the frame by a pin called shackle pin.
- The centre portion of the spring is attached to the front axle by a V-bolt.
- The stiffness or spring rate of the leaf spring is determined by its length, width, and thickness.
- Greater the number of leaves, higher the stiffness.
Air Suspension System
- Air springs are flexible bellows made of textile-reinforced rubber, containing compressed air.
- They are used to carry load on vehicles and provide elasticity or "springiness" when compressed.
- Air springs have three characteristics: they are soft when unloaded, they increase stiffness when loaded, and they maintain constant vehicle height.
- They provide optimum riding comfort in both lightly loaded and fully loaded conditions.
Shock Absorber
- Shock absorbers are used to control vibrations on springs, provide comfortable ride, and act flexible and rigid.
- They are used as a part of the suspension system and provide more resistance to the motion of the spring and road wheel.
- Types of shock absorbers include mechanical, hydraulic, and telescopic shock absorbers.
Telescopic Shock Absorber
- Construction consists of an upper eye attached to the axle, a lower eye attached to the chassis frame, and two-way valves.
- Working involves fluid flowing between the valves to produce a damping force.
- The damping force varies with the speed of the piston.
Types of Suspension System
- There are two basic types of suspension systems: front end suspension and rear end suspension.
- Front end suspension types include independent front suspension and rigid axle front suspension.
- Rear end suspension types include longitudinal leaf spring, transverse leaf spring, and coil spring rear end suspension.
Independent Front Suspension
- Developed in the 1930s to improve vehicle ride control and riding comfort.
- Each front wheel is mounted on its own axle and independently supported by a coil or torsion bar or leaf spring.
- Types of independent front suspensions include longitudinal, transverse, sliding, MacPherson Strut, parallelogram, trailing link, and vertical guide suspensions.
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Description
Learn about the key components and functions of a transmission system in automotive engineering, including the role of gears and shafts in transferring power from the engine to the wheels.
