Rotary systems Flashcards
What is a rotary system?
Any system which has a rotary system at the input and the output
Examples of rotary systems?
Gears
Pulleys
Chains and sprockets
What is a gear wheel?
Basic mechanism which transfers and transforms rotational motion and torque
What is a gear system?
Can change the speed and torque of a system
What is the pitch?
How gears mesh together
How to calculate pitch?
Pitch = π x module
How to calculate module?
Module = reference diameter / number of teeth
How does a spur gear work and what are its uses?
Teeth go straight across the body
Lathes, car gear boxes
What are the advantages and disadvantages of spur gears?
Cheap, simple, uses different materials
Loud/ noisy
How does a helical gear work and what are its uses?
Has more of an angle across the gear wheel, teeth has a curve
Car gear boxes, conveyors
What are the advantages and disadvantages of helical gears?
Less noisy, more efficient
Expensive, larger, heavier
How does a bevel gear work and what are its uses?
Transmits the power through 90 degrees from one shaft to another
Whisks, hand drills, wind turbines
What are the advantages and disadvantages of bevel gears?
Increase/decrease of speed or torque
Only transmits motion through 90 degrees
How does a worm gear work and what are its uses?
Transmits motion through 90 degrees and can decrease speed
Cranes, lifting things
What are the advantages and disadvantages of worm gears?
Reduces speeds by large amounts, increases torque by large amounts
Sliding friction between teeth and worm can cause heat and inefficiency
What is a gear train?
Consists of two or more gears
What is an idle gear?
Changes the direction of the driven gear but doesn’t effect anything else
How to calculate the velocity ratio of a gear?
VR= Number of teeth on driven/ Number of teeth on driver
What is a compound gear train?
Will have two or more gears on a single shaft it reduces VR more than a great train, in a smaller space
What is the velocity ratio of a compound gear train?
VR= Product of driven/ Product of driver
How to calculate output speed in RPM?
Output speed = Input speed/ VR
How to calculate output torque?
Output torque = Input torque x VR
