Check brake pedal travel with, and without, engine running to verify proper power booster operation, Check vacuum supply (manifold or auxiliary pump) to vacuum-type power booster.

Lesson Plan for:

AUT 154-155 Maintenance and Light Repair Section C

Course HS Title: / Maintenance and Light Repair / Program:
KCTCS Courses included in HS Title: (Lesson is prepared for course highlighted.)
KCTCS Course No. / KCTCS Course Title
AUT 110 / Brake Systems
Introduction/Context / This lesson will instruct the student on how to check brake pedal travel with, and without, engine running to verify proper power booster operation, and check vacuum supply (manifold or auxiliary pump) to vacuum-type power booster.
Prepared By / School / Date:
Grade Level / No. Students / No.IEP's: / Lesson Length:
Task
Check brake pedal travel with, and without, engine running to verify proper power booster operation.
Check vacuum supply (manifold or auxiliary pump) to vacuum-type power booster.
No. / Objective
1 / Given a vehicle with a vacuum assisted power brake system and a vacuum gauge, the student will be able to check brake pedal travel with, and without, engine running to verify proper power booster operation, check vacuum supply (manifold or auxiliary pump) to a vacuum-type power booster, and pass a written exam with 100% accuracy by the end of the course.

Connections:

Skills Standards:
OH 001
OH 002
OH 003
OD 002
OD 003
OD 005
New Common Core Standards:
RST 11-12 3
Common Core Technical Standards:
TD-OPS 2
TD-SYS 2
New Generation Science Standards:
HS-PS2-1.
HS-PS3-3.

INSTRUCTIONAL MATERIALS/TECHNOLOGY
Equipment

Quantity / Item / Source
1 / Hand-held Vacuum Gauge / Sears, Snap-on, NAPA

Textbooks and Workbooks

Author / Title/ISBN No. / Edition / Publisher / Pages
Various / ASE Test Prep Brakes / 2013 / Delmar / 36-37
Various / ASE Test Prep Guide / 2009 / Pearson / 330


Content/Presentation/Demonstration Outline

Explain to students that most power brake boosters operate by engine vacuum and atmospheric pressure acting on a vacuum diaphragm. Instruct students that with the engine running, vacuum exists on both sides of the booster diaphragm, and when the brake pedal is applied, a vacuum port is closed which allows atmospheric pressure to enter one side of diaphragm chamber. Let them know that this action moves the diaphragm assembly and applies the master cylinder.
Instruct students that with the engine stopped, they should pump the brake pedal several times, and hold the pedal in the applied position. Explain that when the engine is started, the pedal should move slightly downward if the vacuum supply to the brake booster is normal. If the pedal does not move slightly downward, tell them to check the vacuum hose and the one-way check valve to the brake booster.
Tell students that to check the vacuum brake booster for air tightness, operate the engine for two minutes and then shut off the engine. They should then pump the brake pedal several times with normal braking pressure. Explain that if the brake booster is operating normally, the pedal should go down normally on the first brake application. Let them know that the pedal should gradually become higher and harder to depress with each pedal application.
Instruct students that vacuum assisted power brakes rely on a steady, adequate supply of manifold vacuum. Explain that internal engine problems can affect power assist if manifold vacuum is lower than normal, and that any vacuum leaks will also affect proper booster operation. Tell them that a vacuum leak in the booster assembly can also occur. Let them know that low vacuum or a leaking booster will cause a hard brake pedal with little or no power assist, and that engine vacuum should be 17—20 in/Hg @ sea level at idle.
Tell students that to check for proper vacuum, disconnect the booster hose from the manifold and connect a vacuum gauge. Let them know that on vehicles with auxiliary pumps, test for vacuum at the pump with the engine running. Inform them that vacuum should be 15—22 in/Hg @ sea level, and that they should compare that reading right at the booster to make sure the booster is being supplied with the same vacuum.


Applications/Practice

1 / Students will use a vacuum gauge to measure vacuum at the brake booster with the engine idling.
2 / Student will sit in vehicle with windows rolled up and all accessories turned off and with engine idling listen for hissing sound while the brake pedal is held down.
3 / Students will pull check valve out of brake booster and listen for hissing to indicate the check valve is working properly.


Evaluation and feedback Prior to Testing or Lab Work

1 / Objective 1/ Formative assessment / Instructor will observe students as they practice the procedure to assure correct procedure and safety practices are being followed. A checklist should be utilized to chart student progress on the task. Questioning techniques will be utilized as necessary to demonstrate student comprehension / Adaptations and/or accommodations for special needs students will be added if required.


STUDENT ASSESSMENT:(Assess student progress with performance criteria.)

1 / Objective 1/ Summative assessment / written test questions on stated objective / adaptation and/or accommodations for special needs students will be added if required.
IMPACT--Reflection/Analysis of Teaching and Learning: (How did students’ progress in relation to the state objectives? Was the instruction successful? Analyze samples of student work particularly that which is unsatisfactory, for the purpose of planning further instruction.)
REFINEMENT--Lesson Extension and Follow-up: (To be filled in as the lesson is modified during initial planning and/or during the teaching learning process.)