Part of Lesson Plan: **Turning Brake Drums (updated) By Eli Jaramillo

Activity Overview / Details

Materials needed:

• PowerPoint Presentation "Turning a brake drum" slides 8 and 9
• Four or more brake drums (Will be used by students for measuring)
• Four or more brake drum micrometers (Also to be used by students)
• Safety glasses for all students observing this demonstration

Instructor Note:  Use a brake drum and a brake drum micrometer to demonstrate the following:

(Slide #8):  Instructor:  "Another condition called out-of-round may cause the brake pedal to 'pulsate' .  The drums should be machined to restore roundness of the drum frictional surface.  In this slide, we see a drum being checked for this out-of-round condition."

Instructor Note:  Show a brake drum with an out-of-round condition.  Use the brake drum micrometer on this drum and show the reading on the scale.

Instructor:  "Now we'll measure the drum inner diameter with an accurate brake drum micrometer. Notice the dial and how I fit it to the brake drum. When we measure, there should be no variation in the drum inner diameter greater than .002 inch."

Instructor:  "Any questions on what we've covered so far?"

(Slide #9):  Instructor:  " What's a 'rule of thumb' to follow about turning brake drums?"   (   Drums should be turned only if there are major imperfections or an out-of-round condition).

Instructor:  "What's another important rule of thumb when turning the brake drum on one side of the vehicle?  (Turn the brake drum on the other side to the same diameter).