Think of the steering mechanism in your car (actually the reverse). Think of the point at which your tie rod connects to the front wheel as the place of X's extra rail. At the other end of the tie rod is (for simplicity's sake) the steering column, and therefore the steering wheel.
Now put your car on blocks. Twist the wheel back and forth (just like when the car turns), as if you were changing the distance of that extra rail on X. When you do that, your steering wheel turns. Pretend the steering wheel is the X seat.
Not a good example? OK, try this out. Wrap a string around a pencil three our four times. Hook your index and middle fingers and lay the pencil in it with both ends of string hanging down between your fingers. When you pull the string, simulating the distance of the extra rail getting further from the main rail, the pencil turns. The pencil is the seats.
Still need a better example? Think of your garage door. The bottom of the door is where the extra rail on X is, the seats are connected to the rotary spring at the top of the door. When you move the door, the cables connected between the door and the spring make the spring turn.
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Jeff
Webmaster/Admin - CoasterBuzz.com