land transportation 3 technology education. control »steering »front wheel steering »rear wheel...
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Land Transportation 3
Technology Education
Control
» Steering» Front Wheel Steering» Rear Wheel Steering
» Forklifts, Street Cleaning Machines
» All Wheel Steering» Popular in large vehicles» Operates front and rear wheels at the same
time
Coordinated Steering
» Negative Steering, in which the front and rear tires are steered in opposite directions.
» Aids in parking and decreases the turning radius.
Crab Steering
» Positive Steering, all tires are turned in the same direction
» Used in changing lanes and adds stability
Steering
» Rack and Pinion - Type of steering that changes rotary motion into linear motion.
» Steering wheel is attached to the pinion gear, the pinion gear then moves the rack right or left which in turn moves the wheels right or left.
Articulated Steering
» Used on large hinged vehicles.
» Steering controlled by swiveling the trailing wheels along with the front wheels.
Tracked Vehicles» Tracked vehicles
steer by varying the speed on one of the tracks.
» Tanks, bulldozers and logging equipment use tracks.
» Tracked vehicles can turn around in one spot by moving one track forward and one track backwards.
Suspension Systems
» In-land vehicles suspension systems can include tires, wheels, shocks, springs.» Tires – Two important functions
» Provide cushion as the vehicle travels over bumps
» Provide traction. The contact patch is the part of the tire actually touching the road surface.
Springs
» Coil Spring – Spring made by taking steel rods and forming them around a cylinder.
» Coil springs are placed between the vehicle frame and axle. When the vehicle hits a bump the spring uses potential energy to expand and push the wheel back to the road.
Springs
» Leaf Spring – A series of steel strips, each one shorter than the next.
» Leaf springs are attached to the axle and two points on the vehicle frame. When the vehicle hits a bump the spring flexes up and down.
Shock Absorbers
» Shock absorbers control the roads unevenness, so it is not transferred to the vehicle structure.
» They also help minimize spring oscillation (The compression and rebounding of a spring)
Stabilizer Bars (Sway Bar)
» Long steel rod mounted between wheel assemblies.
» This keeps the vehicle from leaning to far when going around turns.