Automotive General Services Technician Model

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Lesson Plan Industry Sector
Transportation

Lesson Plan Originally Created By: Beau Sunahara

**Synchronizers (updated) by Beau Sunahara

Part of Unit: Transmissions and Drivetrains

Lesson Plan Overview / Details

In this lesson, students will accurately understand how a synchronizer allows a transmission to shift gears while moving. Students will also be working individually, as this lesson is a lecture and video presentation.

Lesson Time

1 Class period
55 Minutes

Prerequisites

Gears lesson

Standards

California Career and Technical Education Standards

California Academic Content Standards (Reinforced)

Objectives and Goals

  • Students will identify the parts of a synchronizer
  • Students will accurately describe how a synchronizer is used during shifts

NATEF Standards

  • Manual Drive Train and Axles: Task C-12 Inspect and reinstall synchronizer hub, sleeve, keys (inserts), springs, and blocking rings.
  • Manual Drive Train and Axles: Task C-5 Diagnose hard shifting and jumping out of gear concerns; determine necessary action.

Vocabulary

Blocking ring
The blocking rings cone rubs on the side of the drive gear cone, causing friction between the two. This causes the output gear, synchronizer, and the output shaft to begin to spin at the same speed.
Hub
Internal part of the synchronizer that is internally splined to the output shaft.
Shift fork
Shift forks fit around the synchronizer sleeves to transfer movement from the gear shift linkage to the sleeve.
Sleeve
Outer sleeve of the synchronizer which slides over the hub, blocker ring, and the dog teeth of a gear. The shift forks slide over the external part of the sleeve.

Activities in this Lesson

  • Non-synchronized first gear - Hooks / Set

    The teacher will tell a story of how a 60's Chevrolet pick-up three-on-the-tree (3-speed manual transmission with shifter on steering column) was not a fully synchronized transmission.  To shift back into 1st gear, one would have to come to a complete stop (coming up to a red light slowing down, then the light changes to green was the worst time) or the gears would grind.

  • Synchronizer - Lecture

    The teacher will lecture explaining how a transmission use synchronizers to shift gears while the vehicle is still moving.

    The teacher will show the internal ribs or teeth of the blocking rings and explain their importance in slowing down the speed of the cone on the various gears.

    The teacher will explain how hard shifting can occur from worn synchronizers if it has already been determined that the clutch is not at fault.  During service or when checking manual transmission fluid, the technician will notice brass-colored debris in the fluid.  This is caused by blocking rings that are starting to wear.

    The teacher will explain how the dog teeth of the gear are used to secure the gears to the hub of the  given synchronizer by having the sleeve slide over both parts locking them together.

    The teacher will demonstrate with a torn-down manual transmission how the hubs are locked to the output shaft, while all the gears can freely rotate on the output shaft.

    The teacher will pass out parts as they explain their specific operation in the synchronizer.

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

    Students will take Cornell-style notes during the lecture.

  • Synchronizer Video - Demo / Modeling

    The teacher will then show the video of a synchronizer in action.

    The teacher will quiz the students to check for understanding of how a synchronizer works.

    Students will take Cornell-style notes during the video, and answer questions at the end of the video.

    • synchro.wmv [ Watch Video ] [ Download Original Video ] This is not the actually CDX video I show the students, the actual video is longer and describes the actions of the synchronizer. This is the only free video I have found of a synchronizer to demonstrate its operation.
  • Closure - Closure

    At the end of the lesson the teacher will give a short quiz.

    After the students turn in the quiz, the teacher will go over the answers to give feedback on the questions.

Assessment

Assessment Types:
Teacher-Made Test,

During the lecture the teacher will call upon students to answer questions to check for understanding.

During the video the teacher will call upon students to answer questions to check for understanding.

This is a mid-unit lesson so the teacher will give a quiz to check for understanding on previous lessons.

  • man trans fund quiz1.doc man trans fund quiz1.doc [ Download ] Mid-unit quiz on gear lesson