Overview

Power transfer systems are:

• Mechanisms that can change the location of a moving body from one spot to another

• Usually from a motor shaft to another shaft

• Can be linear or rotational but we’ll be going over the rotational ones here

• The big three methods: Gears, Sprockets, and timing pulleys which all use some sort of teeth

Power

• Power is equal to Work (force achieved over a distance) divided by Time

• Rotational power can be simplified to Torque times Rotational Speed; because of this principal power transfer methods can trade rotational speed for torque and vice versa (NOTE: an increase in both cannot be achieved without additional power)

Torque

• Torque is for all intents and purposes rotational work!

• A basic equation is T = F * D (T is torque, F is force, and D is distance)

  1. The amount of torque acting on a shaft is the result of the force acting on it multiplied by the distance away from that shaft. An example is through a wrench or a lever

  2. Units are in foot * pounds or Newton * Meters or Kilogram * Meters etc

• Utilizing CAD we can figure out more precise torque measurements by multiplying the sums of the moment of inertia of those objects rotating on a shaft by their rotational acceleration

• Sometime’s the torque of a motor isn’t enough for the job we need to do!

Rotational Speed

• Rotational velocity is measured in Rotations Per Minute  (RPM - how many times a shaft rotates 360 degrees in one minute!) 

• Motors typically start out with a high RPM which is fast

• Utilizing RPM we can convert to linear speed (Example would be calculating how fast the robot can move)