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Chapter 18 Land Vehicular Systems. Objectives Propulsion systems used in land vehicles. Drive systems. Guidance systems. Control systems in land vehicles.

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Presentation on theme: "Chapter 18 Land Vehicular Systems. Objectives Propulsion systems used in land vehicles. Drive systems. Guidance systems. Control systems in land vehicles."— Presentation transcript:

1 Chapter 18 Land Vehicular Systems

2 Objectives Propulsion systems used in land vehicles. Drive systems. Guidance systems. Control systems in land vehicles. Suspension system. Structural system.

3 Propulsion Systems The first way is through the use of an internal combustion system. The second method of propulsion is electricity. The third is a hybrid of both internal combustion and electricity.

4 Internal Combustion Engines The internal combustion engine functions by igniting a fuel to produce hot gases. The hot gases push either a piston or rotor to create mechanical energy. Mechanical energy is used to propel a land vehicle. There are 3 main types of internal combustion engines: gasoline piston engines, rotary engines, and diesel engines. Gasoline piston engines can be found in automobiles, motorcycles, lawn mowers, and snowmobiles. The design of rotary engines (fig 18-4, page 416) decreases the amount of moving parts. Diesel engines have no spark plugs. They rely on the extreme heat of the compressed air to supply the ignition. During the compression cycle the diesel engine only compresses air. The fuel is not added until the compression is complete. This enables diesel engines to be more efficient.

5 Electrical Propulsion Direct electric vehicles: Light rail systems get their power from overhead lines. Other transportation systems such as subway trains receive electric current through a third rail located between the two main tracks. The electric current is then used by the onboard electric motor to propel the vehicle. Indirect electric vehicles: All batteries have specific storage capacity rated in amp-hours, and they must be recharged when they have lost their stored power. Hybrid propulsion: There are two types – diesel electric propulsion used in train engines and gasoline electric hybrid used in automobiles and small trucks.

6 Transmitting Power The components of the drive system (power train) allow the propulsion power to be sent throughout the vehicle. Automobiles use transmissions, drive shafts, differentials, axles, and wheels to create movement of the vehicle (fig 18-16, page 423). The first job of the drive system is to multiply the amount of torque the engine produces. Transmission systems are devices that provide for multiplying, dividing, or reversing the mechanical power and torque coming out from the engine. Manual transmissions use a lever called a stick shift to control and engage different combination of gears. First gear typically has a gear ratio of 3:1. This slows the output shaft and provides the torque needed to move the vehicle from a stopped position.

7 Guidance Systems Navigational aids include maps, signs, and electronic navigation systems. Maps: Different symbols are used to denote different types of roads. Navigation Systems: The system is connected to the global positioning system (GPS). If the destination has been entered, the navigation system can help the driver get to the destination on display and verbally. Signage: Regulatory, warning, and information signs give drivers information and directions. Electronic Guidance Systems: Systems use sensors to alert drivers.

8 Control Systems Changing speed: For internal combustion engines, you accelerate by forcing more fuel into the engine through a throttle system. In electric vehicles, more power is sent to the motors which increases speed. Hydraulic braking system: The hydraulic braking system used on modern wheeled vehicles link a master cylinder to a brake pedal and to one or more brake cylinders at each wheel (fig 18-30, page 432). The wheel cylinders expand to activate the vehicle’s brakes. Antilock braking system: An ABS helps the driver control the vehicle while braking and enables the vehicle to stop faster. Pneumatic brakes: Railroad cars use pneumatic brakes (air brakes) to decelerate. They use compressed air to operate the brake cylinder. Controlling direction: Most vehicles rely on front wheel steering for control. Forklifts and street cleaning vehicles that need to have a tight turning radius are designed with rear wheel steering.

9 Suspension Systems In land vehicles suspension systems can include tires, wheels, shocks, and springs. Pneumatic tires: Air filled tires provide a cushioning effect as the vehicle travels over bumps and ruts. Springs: Can be coil spring, leaf spring, or torsion bars (fig to 85, page 441). Shock absorbers: Shock absorbers absorb the road’s unevenness so it is not transferred to the vehicle structure. Stabilizer bars: It is a long steel rod mounted between the two front wheel assemblies to keep the vehicle from leaning out too far when the vehicle is going around corners.

10 Structural Systems Automobile Structural Systems: Main parts are the body (exterior of vehicle) and the chassis (frame). Unibody construction is common on many vehicles. This structure combines the body and frame into one unit (fig , page 444).

11 Support Systems Roads and highways: The United States has an excellent system of interstate highways that began to develop in the 1950s. Railroads: First the route is planned and then the land is obtained. There can be no steep grades or sharp bends. Bridges: Bridges span waterways, ravines, and other barriers. Suspension bridges are capable of spanning the longest distance (Golden Gate Bridge in California). Tunnels: They are often more cost effective than building roads over and around the mountains. Tunnels are also used under water. Prefab tubes are sunk in the water, anchored and pumped out. Passenger Facilities: Bus stations, airport terminals, and train stations provide comfort and service for people who are travelling. Cargo Facilities: These facilities have well designed spaces for storage and movement of freight. Vehicle Maintenance Facilities: Big companies usually own and operate their own maintenance facilities.

12 Summary The internal combustion engine functions by igniting a fuel to produce hot gases. The hot gases push either a piston or rotor to create mechanical energy. Mechanical energy is used to propel a land vehicle. There are 3 main types of internal combustion engines: gasoline piston engines, rotary engines, and diesel engines. Diesel engines have no spark plugs. They rely on the extreme heat of the compressed air to supply the ignition. Direct electric vehicles: Light rail systems get their power from overhead lines. Automobiles use transmissions, drive shafts, differentials, axles, and wheels to create movement of the vehicle. Navigational aids include maps, signs, and electronic navigation systems. Antilock braking system: An ABS helps the driver control the vehicle while braking and enables the vehicle to stop faster. Automobile Structural Systems: Main parts are the body (exterior of vehicle) and the chassis (frame). Unibody construction combines the body and frame into one unit.

13 Home Work 1. What are the 3 main types of internal combustion engines? 2. What are the components of the drive system (power train)?


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