Chapter 19

1. Chapter 19 Control Of A Vehicle

2. Controlling Speed • Drive System-Automobiles send power through transmissions, drive shafts, universal joints, differentials, axels, and wheels to move the vehicle. • Clutches- Provides control for the separation of power and drive system. • Transmission Systems- The devices that provide for multiplying, dividing, or reversing the mechanical power coming from the engine.

3. Controlling Speed Cont. • Manual Transmissions-You the driver are the controller of the car. • Automatic Transmissions- You do not use a clutch with a automatic transmission because it uses a fluid coupling to receive power from the engine. It also uses a unlimited number of torque ratios. • Acceleration- It is changing the speed of a vehicle so that it moves faster. The propulsion system changes the method of acceleration the car will have.

4. Controlling Speed Cont. • Deceleration- It is the slowing down or braking of a vehicle. Many types of manufacturers have designed brakes to help deceleration. • Hydraulic Braking Systems- It links a master cylinder to a brake pedal and to one or two brake cylinders at each wheel. Its connected with steel tubing that sends the hydraulic fluid to the brakes. Drum and Disk brakes are the devices that uses friction to slow the vehicle down. • Drum Brakes- The drum brake uses two brake shoes that fit inside of the brake drum. To stop the vehicle the shoes push out towards the drum the stop the vehicle with the friction.

5. Controlling Speed Cont. • Disc Brakes- Disc brakes use a rotor instead of a drum. A brake caliper goes around it and when you are stopping it is squeezed against the disc, causing friction to stop the vehicle. • Brake Protection- Since there is lots of heat generated in a brake device you have to use certain material so that they will last. You have to use special asbestos parts, they resist heat very well but can be dangerous if inhaled causing cancer. • Power Brakes- Power Brakes are found on many modern automobiles. It uses a vacuum device, which allows the driver to put less pressure on the pedal when stopping. It works just as good as the other brakes, but more modern.

6. Controlling Speed Cont. • Anti-Lock Braking Systems – Manufactures have installed sensors to help monitor the vehicle speed. When you brake the sensor activates an electronic controller which applies and releases brake pressure to prevent your brakes from locking up. It also helps improve safety.

7. Controlling Direction • Vehicles on Rails and Guideways- Railroad trains, Electromagnetic Levitation vehicle, Monorails, and other vehicles travel on tubes and pipes. They can only go forward or backwards. Which everyway the guideline goes the vehicle must go. • Built-In Railroad Steering – There is a gap in between the wheel so when the train is making a turn it can shift its weight to line up to make the turn. • Steering Wheeled Land Vehicle- There are four basic systems to controlling the direction of the vehicles. Front steer, rear steer, front and rear steer, and crab steer. Four wheel steering is most common now.

8. Controlling Direction Cont. • Wheel Positioning-The wheels that pivot to steer is positioned with the caster and chamber. Caster is positioning the wheel so that where it contacts the road is actually behind the centerline of the steering axis. The Chamber is a tilting of the front wheels slightly off the vertical. • Articulated Frame Steering- Vehicles designed for mass transit, farm operation, and construction have an articulated section in the middle of the vehicle. This allows long vehicles to have a small turning radius.

9. Controlling Direction Cont. • Steering Tracked Land Vehicles- Tanks, Bulldozers logging equipment, and other off road vehicles all use tracks which improves there traction on different terrains. By decelerating one of the tracks and accelerating the other the driver can pivot the vehicle better. Tracked vehicles can move around in one spot.

10. Steering Marine Vehicles • Vehicles that move through water use a rudder. There part of the steering as well. A Hovercraft has rudders behind the propulsion to move it. Jet Propelled vehicles do not use rudders because they move in the direction of the thrust.

11. Steering Marine Vehicles Cont. • Directional Control of lighter-Than-Air vehicles - Hot air Balloons can only control vertical flight by controlling the amount of hot air in the vehicle. Blimps and dirigibles are lighter than air vehicles that are able to control both vertical and horizontal dimensions of flight. • Steering Airplanes- The elevators, flaps and ailerons control the vertical dimension of flight. The ailerons and the rudder controls the lateral movement of the plane.

12. Steering Marine Vehicles Cont. • Steering Helicopters- Helicopters can move in different directions with greater speed and agility than airplanes. The helicopter has directional control which is possible by cyclical pitch. The pilot can control which way he wants to go by using the cyclical pitch. He can move forwards, backwards, and side to side.

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15. Key Words • Acceleration • Articulated • Blimps • Camber • Caster • Clutches • Control Systems • Cyclical Pitch • Deceleration • Degrees of Freedom

16. Summary • A Control system consist of the parts of a vehicle that controls speed and direction. This is need to run a transportation system. Clutches and fluids are used to transmit power from one source to another. Most vehicles rely on forcing additional fuel into the system to accelerate. Drum and Disk brakes are used to slow down a vehicle. The Asbestos linings are used to protect the metals. Marine vehicles use rudders to change there direction.