Vehicle Classifications Quiz

Vehicle Classifications

• A vehicle is a machine used for transporting passengers or goods.
• Wheeled motor vehicles move on wheels, applying steering and traction forces against the ground.
• Common examples are cars, trucks, buses, and motorcycles.
• This study focuses on passenger cars.
• EU general classification of wheeled motor vehicles:
  • Category M: Motor vehicles with at least four wheels designed and constructed for the carriage of passengers.
    • M1: Vehicles for passenger carriage with no more than eight seats, including the driver's seat.
    • M2: Vehicles for passenger carriage with more than eight seats, and a maximum mass not exceeding 5 tons.
  • Category N: Motor vehicles with at least four wheels designed and constructed for the carriage of goods.
    • N1: Light commercial vehicles for goods transport with a maximum mass not exceeding 3.5 tons.
    • N2: Large goods vehicles for goods transport with a maximum mass exceeding 3.5 tons but not exceeding 12 tons.
  • Category L: Two-wheel vehicles (motorcycles), and quadricycles.
    • L3e: Motorcycles without a sidecar with an engine capacity over 50 cm³ and a maximum design speed over 45 km/h.
    • L6e: Quadricycles with an unloaded weight not exceeding 350 kg (excluding batteries in case of electric vehicles), a maximum design speed not exceeding 45 km/h, and an engine cylinder capacity not exceeding 50 cm³ for spark ignition engines, or a maximum net power output not exceeding 4 kW for other internal combustion engines, or a maximum continuous rated power not exceeding 4 kW for an electric motor.

Passenger Car Categorization

• Passenger cars don't have formal categories beyond Category M1.
• Categorization is based on comparison to well-known models, e.g., Volkswagen Golf might be in the Ford Focus size class.
• Common passenger car segments include mini cars (A), small cars (B), medium cars (C), large cars (D), executive cars (E), and luxury cars (F).
• Additional segments include sport coupés (S), multi-purpose cars (M), and sport utility cars (J).

Chassis and Body Overview

• Chassis is the base frame of the vehicle.
• Components like engine, transmission, suspensions, controlling systems (braking, steering), and electrical parts are mounted on the chassis.
• The chassis is the main mounting for all components, including the body, which acts as a carrying unit.
• During a crash, the chassis must provide maximum protection for passengers, with high torsional and bending rigidity.
• Body refers to the outside shell of the vehicle.
• The bodywork aims to offer comfortable accommodation for the driver and passengers, suitable protection from weather, and an attractive design that appeals to customers.
• Vehicle bodies need to be practical for entering and exiting, with ease of reaching controls.

Most Common Chassis-Body Types

• Unibody (unitized body): A single, integrated structure of chassis and body.
• Offers superior crash protection.
• High volume manufacturing is cost-effective but high initial investment for large molds makes it less feasible for small-scale production.
• Examples include passenger cars, SUVs, and light commercial vehicles.

Conventional Unibody

• Constructed from hollow sheet-steel tubes. Metal panels are welded onto the tubes.
• Approximately 5000 spot welds.

Ladder Chassis

• Simplest and oldest chassis design, with two beams and cross-members.
• Simple and robust; offers low torsional rigidity to weight ratio.
• Often made from steel.
• Preferred for heavy-duty commercial vehicles (trucks, buses, off-road vehicles).

Space Frame Chassis

• Lightweight rigid structure constructed from struts in a geometric pattern.
• Tubes can be curved, resulting in high torsional and bending rigidity to weight ratio.
• Suitable for race cars, sports cars, and special-purpose vehicles.
• High manufacturing costs often hinder use in mass production.

Body and Chassis Materials

• Sheet steel (various alloys) is the most common material for chassis and body structures, 0.6-3.0 mm thick.
• Steel offers strength, ductility, and cost efficiency, but is heavier.
• Aluminum is also used to reduce weight, commonly in extruded sections and sheet components.
• Fiber glass (glass reinforced plastics) is lightweight and often used for bodies of sport cars.
• Carbon fiber offers the best strength to weight ratio, but high cost hinders widespread use.
• Thermoplastics are frequently used for separate body components (bumper, spoiler, etc.) due to cost efficiency and resistance to corrosion.

Body Surface

• Corrosion is a major problem for body surfaces, particularly in metal components.
• Rust (oxidation of iron) weakens metal components.
• Solutions for controlling corrosion include pre-coating steel components (e.g., galvanization, hot-dip galvanization)

Galvanization

• Process of applying a protective zinc coating to steel to prevent rust.
• Hot-dip galvanization is a common method where steel parts are submerged in molten zinc.
• Often followed by painting to prevent corrosion.

Geometrical Design

• Some geometrical design modifications contribute to corrosion reduction.
• Flanged joints, minimized sharp corners, and open ventilation must be considered.

Aerodynamics

• Automotive aerodynamics reduces drag force, wind noise, and prevents lift force.
• For racing cars and sports cars, downforce is also important to enhance road holding.
• Key factor in drag is pressure variations caused by the vehicle moving through air.

Drag Area

• Cd. A is the fundamental parameter for aerodynamic resistance.
• Calculated from the vehicle's body shape and size.
• Cd (drag coefficient) is separately evaluated.

Vehicle Collisions and Safety

• Vehicle collisions are a significant cause of injury and death.
• Active safety technologies aim to prevent crashes, such as good visibility from the driver's seat, low interior noise level, good handling and road holding.
• Modern active safety systems include Anti-Lock Braking System (ABS)
• Electronic Stability Control (ESC)
• Traction Control System (TCS)

Collision Avoidance

• Sensors that place warnings to prevent or reduce impact force.

Crashworthiness

• The science of minimizing injuries and fatalities in vehicle collisions.
• Chassis must satisfy 5 basic requirements: Maintain Survival Space, Restrain the Occupants, Prevent Ejection, Transfer Energy and Prevent Fire.

Crumple Zones

• Parts designed to displace and absorb energy from a collision, reducing force on occupants. Positioned at front, rear and occasionally side of the vehicle.

Passive Safety Equipment

• Seatbelts, airbags, head restraints, and interior padding reduce impact forces during a crash.

Crash Testing

• Destructive testing of vehicle to ensure safety standards according to scientific and safety standards.

Suspension Systems Overview

• Suspension systems aim to maximize tire-to-road contact area.
• This enhances road holding, steering stability, and ride comfort.

Suspension Components

• Springs: Resist vehicle weight and absorb road shocks (important aspects of suspension performance).
• Damper: slow down oscillations caused by the spring system, and transform kinetic energy caused by motion into hydraulic heat energy

Spring Types

• Leaf Spring: Multi layered metal "leaves"
• Coil Spring: Wound into a spiral.
• Torsional Spring: A steel rod treated with heat/pressure to absorb rotational forces.

Anti-Roll Bar

• Used to prevent vehicle body from rolling during high lateral acceleration in turns.

Control Arms and Joints

• These linkages of the suspension mechanism, control how the wheels move according to their kinematic requirements.
• Made usually from sheet-steel, metal or alloys.
• Spherical and revolute joints.

Suspension Kinematics

• The most important kinematic parameters affecting driving performance are: -Camber angle: the tilt of the wheels, -Caster angle: affects steering, -Kingpin angle: directs steering, -Toe angle: wheel alignment in the forward direction.

Wheelbase and Trackwidth

• Wheelbase: Distance between the centers of the front and rear axles.
• Trackwidth: Distance between the centers of the left and right wheels.

Sprung and Unsprung Masses

• Sprung mass: includes a vehicle's body, frame, motor, and transmission which the springs support.
• Unsprung mass: includes the wheels, brakes, half of the control arm's weight

Suspension Types

• Dependent (rigid axle) and independent suspensions. Dependent systems link wheels together (their movement affects each other) while Independent systems allow wheels to move independently.

Steering Systems Overview

• Steering is a collection of components involved in controlling the vehicle's direction of motion.

Basic Steering Methods

• Differential steering on tanks and some specialized vehicles.
• Articulated steering on heavy machinery (a hinged chassis).
• Fifth-wheel steering, used for towed vehicles.
• Ackerman steering (a crucial geometric arrangement for proper turning radius) is also noted.

Steering Components

• Steering wheel
• Steering column
• Steering gear (e.g., rack and pinion)
• Power steering (hydraulic or electric)

Turning Radius

• Turning radius is the radius of the arc described by the center of the wheel during the shortest turn. Using Ackerman steering is shown

Tires and Wheels

• Tires are continuous bands with treads that roll on the ground, road surface, or prepared tracks.
• Two main types: Steel (e.g., railroad vehicles) & Rubber.
• Pneumatic tires (with air) are more common for cushioning.

Pneumatic Tire Properties

• Comfortable ride
• Good steering
• Stability in drive/cornering
• Durability and wear resistance
• Economical wear

Rolling Resistance

• Resistance when a tire rolls on a flat surface.
• Depends on numerous factors: tire material, wheel radius, surface adhesion, forward speed

Tire Codes

• Tires are identified by alphanumeric codes, often molded into the sidewall, containing standardized information like Speed Rating, Load Index, Rim Diameter, Construction type, and Intended Vehicle class

Drivetrain Configurations

• Rear-wheel drive
• Front-wheel drive
• All-wheel drive

Components of a Drive Train

• Energy Supplying Device: (battery, electric motor, or muscular exertion),
• Control Devices: (pedal, lever, or sensors)
• Transmission Devices: (gears, chains, and belts).

Clutches

• The clutch is a part of transmission that connects and disconnects the engine from the drive train.
• Dry plate friction clutch: with a pressure plate, clutch disk, bonded/riveted friction surfaces, and a flywheel
• Wet plate friction clutch: Immersed in lubricating fluid to assist heat dissipation

Torque Converters

• Converts engine's mechanical energy into hydraulic energy.
• Helps transmission multiply or increase torque at low speed ranges

Transmissions Overview

• Transmissions convert torque and rotational speed.
• Allow for forward and reverse motion, adapting to wheel speed variations in turns (curves).

Manual Transmissions

• This involves switching gears manually, typically using a gear shifter.
• Two main Types: Sliding mesh gearboxes, Constant mesh gearboxes

Automatic Transmissions

• Hydraulic automatic transmissions have an automatic gear shift mechanism
• Includes components: hydrodynamic torque converter (initiates motion & torque multiplication), planetary gear sets (different gear ratios), hydraulic pump (pressurizes hydraulic system), and transmission control system (for automatic gear selection)

Automated Manual Transmissions

• Use a combination of manual and automatic components for the gear shifting process. For instance, electro-hydraulic systems utilize electronic sensors, actuators and processors to maintain the appropriate timing

Dual Clutch Transmission

• Has two sets of clutches for the odd and even gearsets. Helps avoid the lengthy gear change delays of a manual transmission

Continuously Variable Transmissions (CVTs)

• Provides a continuous range of gear ratios without discrete steps.

Hydrostatic Transmissions

• Transmits power hydraulically; commonly used in heavy machinery(e.g., excavators)

Electric Transmissions

• Converts engine power to electricity using electric generators and converts this electricity to mechanical power again using electric motors.

Differentials and Drive Shafts

• Differentials are devices that enable the drive shafts to rotate at different speeds, necessary for turning.

Drive Shaft Joints

• Cardan joint (Hooke's joint) is a spatial mechanism for transmitting rotary motions to different axes. Allows for a variable angle.
• Constant velocity joints (CV joints) are two types: Rzeppa and Double-Cardan joints. These maintain consistent output shaft speed even with a variable angle.

This list provides a comprehensive summary, encompassing various aspects of a vehicle's components, their workings, and the different types available. Further details are often necessary for a deeper understanding of each specific component within a vehicle.