Basics
What is a machine?
A set of elements or parts that work together and use energy to perform a task and obtain a result
What is a lever?
a rigid bar that can pivot on a point of support called a fulcrum
What is a pulley?
wheel with a grooved rim used to lift heavy loads
What is a friction wheel?
A set of two wheels located one next to the other. Motion is transmitted between the wheels by the friction between them.
What is the driver element?
feeds energy to the machine
What is the effort?
The applied force
How does a fixed pulley change the effort needed?
It doesn't change the amount of effort needed, but it does change the direction of effort
What units do we use for the rotation speed of friction wheels?
Revolutions per minute (rpm)
What is the driven element?
receives the force produced in the machine
What is the resistance?
The load to be lifted
What is a moveable pulley?
Move vertically and turn when we pull on the rope
What is the transmission ratio?
ratio between the size of the wheels and the speed of rotation
What is the converting and/or transmitting element?
transmits and/or converts (transforms) the motion (movement) from the driver element to the driven element
What is the law (equation) of the lever?
Law of the lever: E * Ae = R * Ar
What is a pulley system?
Combination of fixed and moveable pulleys
Speed multiplier increases speed, while speed reducer decreases speed
What is a mechanism?
devices that transmit and/or convert motion
What happens when the distance of effort from the fulcrum increases?
The amount of effort needed decreases (for a given resistance and distance of resistance)
How does a moveable pulley change the effort needed?
For every moveable pulley in a pulley system, the effort required is reduced by half
What is the equation of the transmission ratio?
i = w1/w2 = d2/d1