California Career and Technical Education Standards

• T.C.C8.4 Understand the function and operation of automatic and manual transmissions and ...

California Academic Content Standards (Reinforced)

• ELA.8.R.CAGT.2.5 Understand and explain the use of a complex mechanical device by following techn...3
• M.5.NS.2.4 Understand the concept of multiplication and division of fractions.1
• M.5.NS.2.5 Compute and perform simple multiplication and division of fractions and apply th...1
• M.6.AF.1.1 Write and solve one step linear equations in one variable.1
• M.6.NS.1.2 Interpret and use ratios in different contexts (e.g., batting averages, miles pe...1

• Bicycle discussion - Hooks / Set

  After students are seated, I ask if they have ever ridden a multi-geared bicycle before. What do they do when they ride up hill? What do they do when they ride down hill? (If students have never ridden a multi-geared bike, I ask how it feels when they ride uphill.)

  Students usually answer, "Change gears!"  Teacher will try to ascertain previous knowledge of students by clarifying which direction would they shift gears (high or low).

  Teacher will ask students to predict whether or not they could start pedaling their bike in the highest gear.

  After a short discussion, we talk about the day's objectives so students know what we are doing for the day.

  • bike2.jpg [ View Image ] [ Download Original ] Riding a bike up hill
• Types of gears discussion - Lecture

  By dividing the number of teeth on the driven gear by the number of teeth on the drive gear, we get our gear ratios between two gears.  If a driven gear has 24 teeth and a drive gear has 12 teeth, the resulting calculation will be (24 / 12 = 2) which gives us a gear ratio of 2 : 1.

  Students must also describe which direction each gear will turn if the first gear (yellow) is being spun clockwise.

  Teacher will explain as the first gear (yellow gear) rotates clockwise, the second gear (red gear) will rotate in the opposite direction (counter-clockwise) while the last gear (blue gear) will rotate in a clockwise motion.

  Teacher will show the animation of two gears spinning while marked with a white dot.

  The teacher will ask for questions at the end of the lecture to clarify explanations.

  Students will take Cornell-style notes during lecture.

  • Bevel & Spur gears [ View Image ] [ Download Original ]
• Calculating ratios - Demo / Modeling

  By dividing the number of teeth on the driven gear by the number of teeth on the drive gear we get our gear ratios between two gears.  If a driven gear has 24 teeth and a drive gear has 12 teeth the resulting calculation will be (24 / 12 = 2) which gives us a gear ratio of 2 : 1

  Students must also describe which dirction each gear will turn if the first gear (yellow) is being spun clock-wise.

  Teacher will explain as the first gear (yellow gear) rotates clockwise the second gear (red gear) will rotate in the opposite direction (counter-clock wise) while the last gear (blue gear) will rotate in a clock wise motion.

  Teacher will show the animation of two gears spinning while marked with a white dot.

  The teacher will ask for questions at the end of the lecture to clarify explanations.

  Students will take Cornell style notes during lectures.

  • Gears [ View Image ] [ Download Original ] Gear teeth picture
  • How Gears work.avi [ Watch Video ] [ Download Original Video ]
• Identify & ratio practice - Group Work

  Students in groups of two can identify different types of gears.

  Teacher will pass out spur gears, helical gears, bevel gears, and hypoid gears.

  The new gears (bevel and hypoid) will proceed into a new discussion on different types of gears for differential.

  • Non identified gears [ View Image ] [ Download Original ] Blank gear picture
• Calculating two ratios

  Now students will individually calculate a final ratio from two different gear ratios. After this exercise, students will now predict how to calculate final drive ratio.

  The teacher will give a differential gear ratio of 3 : 1 and students must calculate final drive ratios.

  The teacher will give the formula differential gear ratio X current gear selected = final drive ratio.

  The teacher will write on the board differential gear ratio 3:1, 1st gear 3:1, 2nd gear 2:1, direct drive 1:1, and overdrive .75:1 .

  Some calculators are provided, although students may use their own calculators.

  • Final Drive WS [ Download ] Final drive work sheet
  • gear train animation.wmv [ Watch Video ] [ Download Original Video ]
• Closure - Closure

  At the end of the lesson, the teacher will collect the final drive work sheets and ask for any final questions from the students.