1. Topic 2: The Wheel and Axle, Gears, and Pulleys
Mechanical Systems
Topic 2: The Wheel and Axle, Gears, and Pulleys

2. A winch consists of a small cylinder and a crank or handle.
A winch works much like a lever.
The radius of a wheel is the distance from the center
of the wheel to the circumference.
The radius is like the load arm of the lever.

4. A wheel and axle device is any device that is attached in the center to the axle and it causes it to turn. The wheel does not even have to be round.
Wheel and axles can provide a mechanical advantage and generate speed, however they require a large effort force to produce a small force on the load.

5. A gear is a rotating wheel like object with teeth around its rim.
A group of two or more gears is called a gear train.
The driving gear or driver is the first gear to turn. It is usually attached to the motor.
The gears that move as the result of the driver are called driven gears or followers.

6. http://www. youtube. com/watch
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7. Can gears turn each other without touching each other?
Yes! If connected by a chain or belt.
A gear with teeth that fit into a chain is called a sprocket.
The teeth have to be the same size and spacing on all gears involved. They can have a different number of teeth.
The relationship between the smaller gear and the larger gear is called the speed ratio.
Speed ratio is calculated using the following formula:
Speed Ratio = _Number of driver gear teeth__
Number of follower gear teeth

8. Start at 7:29

10. Pulleys
A pulley is a grooved wheel with rope or chain running along the groove.
They are similar to class 1 levers but have rope instead of a bar. The axle is the fulcrum, the rope on each side of the pulley is the effort and load arm. However effort arm and load arm are the same.

11. A fixed pulley is attached to something that does not move.
They can change the direction and motion of the effort force and makes certain movements more convenient.
A movable pulley is attached to something else and is usually supported by the rope.

12. Combinations of pulleys can be used to lift very heavy or awkward loads. i.e. block and tackle pulley.
A compound pulley is several pulleys working together.