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

Activity Overview / Details

Materials needed:

• Whiteboard: (Write the following) Unit:  Brakes.  Lesson today:  "Turning Brake Drums"
• Worksheet:  Brakes and a Close Call!

Instructor Note:  As students walk in, have them pick up the worksheet Brakes and a Close Call!  and start working on it while you're taking roll.  This is an ungraded worksheet that will be used for discussion.  It will help get the students settled and in tune with the topic for the lesson.

Instructor:  "Here's the scenario:  You're driving out of the mountains in a clean 1950's vintage pickup truck. Most late-model vehicles have disk brakes, however your truck sports drum brakes all around, as it came from the factory.  It's a collector vehicle once owned by a relative, so you want to keep it all original.  And you also keep it well maintained.  This includes the brake job you had done on it about a month ago.  So you feel confident as you negotiate the narrow road and brake for the curves.  Suddenly coming around a blind curve, you encounter a rock slide that covers the road ahead.  You press on the brake pedal hard, only to find that the brakes aren't responding a quickly as you need.  You're heading straight for the rock slide, slowing down, but maybe not quickly enough..."

Instructor:  "Fast forward to today and this class.  Most of you have either had experience or heard from someone in which brakes had an affect on either a vehicle accident or a close call."

Instructor Note:  Call on a few students to share some of their 'close call' experiences.  You're looking for one that shared a scenario involving brake fade.

Instructor:  "A few of you have shared close call experiences pertaining to vehicle brakes.  All of them shared the same braking requirement:  Stop the vehicle as quickly as possible.   What specific brake problems might have caused the brakes not to have the frictional 'grab' necessary to stop the vehicle on time?"

Instructor Note:  You may get answers such as worn out brakes, low brake fluid, leak in the hydraulic system.  Those are all correct.  For our purposes, what you're looking for are the key words 'excessive heat' which can cause brake fade.  If students don't target in on that, 'lead' them into a discussion about metal thickness and the ability to absorb or store heat (i.e. brake drums turned too far causing a 'thin metal' condition, so they can't absorb the heat as readily, resulting in brake fade).

Instructor:  "Excessive heat could be caused by many things.  Dragging brakes, misadjustment, weak brake shoe return springs, these could all cause this issue.  Another factor is metal thickness on the brake drum itself."

Instructor:  "The other part of your worksheet asked you to list three important requirements of a brake system.  What do you feel these requirements are? (You're after Basics:  Stop quick, straight, every time.) (Call on students vs. asking for raise of hands.)

Instructor:  "Today's lesson will cover the very important operation of turning a brake drum to ensure that the vehicle stops quick, straight, and every time."

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