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.