Basic Practical Mechanics By Benjamin Kidd Benjamin W. Kidd - ENGR-162/12

Benjamin W. Kidd - ENGR-162/12 Today’s Lesson Gears Belt Drives Pulleys Benjamin W. Kidd - ENGR-162/12

Benjamin W. Kidd - ENGR-162/12 What are they for? Mechanical Advantage Transmission of mechanical power Change in rotational velocity Change in direction of movement Benjamin W. Kidd - ENGR-162/12

The Terminology of Gears Gearset – Two (or more) gears used to translate rotational motion from one shaft to another. Benjamin W. Kidd - ENGR-162/12

The Terminology of Gears Mesh Point – Place where the teeth from individual gears come together. Benjamin W. Kidd - ENGR-162/12

The Terminology of Gears Pinion – The “driving” gear (usually the smaller of a pair). Benjamin W. Kidd - ENGR-162/12

The Terminology of Gears Pitch – A measure of compatibility of gears Benjamin W. Kidd - ENGR-162/12

Different Types of Gears Spur Helical Bevel Worm From www.lego.com From www.lego.com Benjamin W. Kidd - ENGR-162/12

Benjamin W. Kidd - ENGR-162/12 Speed of Gears Rotational Velocity to Angular Velocity, ω Example: 40 RPM Benjamin W. Kidd - ENGR-162/12

Benjamin W. Kidd - ENGR-162/12 Velocity Transfer r = Radius of gear ω = Angular Velocity N = Number of teeth on the gear Remember, Pinion (subscript “p”) is the “input” or “driving” gear. Benjamin W. Kidd - ENGR-162/12

Velocity Transfer Example What’s the RPM of the gear pictured meshed with the All Electronics motor DCM-216? DCM-216 RPM ≈ 1200 RPM Benjamin W. Kidd - ENGR-162/12

Benjamin W. Kidd - ENGR-162/12 Answer? 240 RPM Benjamin W. Kidd - ENGR-162/12

Benjamin W. Kidd - ENGR-162/12 Torque Torque = Force x Radius of Lever Torque Transfer Equation From Previous Example Benjamin W. Kidd - ENGR-162/12

Benjamin W. Kidd - ENGR-162/12 Belts and Chain Drives What are some Examples of these? Benjamin W. Kidd - ENGR-162/12

Benjamin W. Kidd - ENGR-162/12 Pulley Systems What is a pulley? Benjamin W. Kidd - ENGR-162/12

Pulley Systems Example Benjamin W. Kidd - ENGR-162/12 Photos By Charles Mason

Benjamin W. Kidd - ENGR-162/12 Pulley Systems Mechanical Advantage Distance Benjamin W. Kidd - ENGR-162/12