Inspect and test hydraulically-assisted power brake system for leaks and proper operation; determine necessary action
Lesson Plan for
AUT 186-187/AUT 292
Automotive Service Technology Section C/Automotive Special Problems
Course HS Title: / Automobile Service Technology/Special Problems / Program:KCTCS Courses included in HS Title: (Lesson is prepared for course highlighted.)
KCTCS Course No. / KCTCS Course Title
Introduction/Context / This lesson will instruct the student on how to inspect and test hydraulically-assisted power brake system for leaks and proper operation, and determine necessary action. Knowledge of these techniques and the skills required to correct problems associated with this task are necessary for a student to acquire if they wish to compete for high paying, high skilled jobs in an Automotive Repair Facility. Entry level technicians need to be able to perform this task to 100% accuracy. Incorrectly performing this task can lead to an automobile accident or create customer satisfaction issues.
Prepared By / School / Date:
Grade Level / No. Students / No.IEP's: / Lesson Length:
Task
Inspect and test hydraulically-assisted power brake system for leaks and proper operation; determine necessary action
No. / Objective
1 / Given the proper tools and instruction, the student will be able to inspect and test hydraulically-assisted power brake system for leaks and proper operation; determine necessary action and pass a written test covering the task with 100% accuracy.
Connections:
Skills Standards:OH 001
OH 002
OH 003
OD 002
OD 003
OD 005
Common Core Technical Standards:
TD-SYS-2
New Common Core Standards:
RST 11-12.2
RST 11-12 3
New Generation Science Standards:
HS-PS2-1.
HS-PS3-3.
INSTRUCTIONAL MATERIALS/TECHNOLOGY
Teacher Designed Materials and Other Handouts
Textbooks and Workbooks
Various / ASE Test Prep/Brakes / Fifth / Delmar / 37-38
Supplies
As Needed / Power Steering Fluid / Various
Content/Presentation/Demonstration Outline
Explain that as the brake pedal is depressed, the booster pushrod and piston are moved forward. This action causes the spool valve to move and allow fluid flow behind the power piston. As hydraulic pressure builds, it actuates the master cylinder.
Tell students that the accumulator is used as a back-up should the hydraulic power source fail. Accumulators are either spring-loaded or contain gas under pressure. Instruct students that the accumulator is filled with hydraulic fluid and is pressurized when the brakes are applied. If the engine stalls or a failure occurs in the power steering pump, the accumulator will have an adequate amount of pressurized fluid to provide one to three power assisted brake applications. To test the accumulator, tell students to run engine and then shut off. Wait five to ten minutes and test brake assist. Let them know that if the accumulator is working correctly, there will be two to three assisted applications.
Instruct students that the inspection and testing of a hydro-boost system must include a complete inspection of the power steering pump, belt, lines, hose connections, and the hydro-boost unit. Let them know that any leaks in the power steering system will affect hydro-boost operation. Explain that aerated power steering fluid will also cause the hydro-boost system not to function correctly. Low fluid level can cause a moan with a vibration in the pedal and steeling column, usually experienced during parking or low speed maneuvers. It’s important to remember that the pressure needed to actuate the hydro-boost unit and master cylinder originates from the power steering pump assembly, which is usually operated by a belt, driven by the engine. A slipping belt or lower pump pressure will affect hydro-boost operation.
Inform students that it’s important to remember that the pressure needed to actuate the hydro-boost unit and master cylinder originates from the power steering pump assembly, which is usually operated by a belt, driven by the engine. Let them know that a slipping belt or lower pump pressure will affect hydro-boost operation.
Teach students that bleeding the power steering system will be necessary after repairs are made to the power steering system or to the hydro-boost assembly. To bleed the system, have students perform the following procedure:
1. Tell them to start the engine and apply the brake pedal several times while turning the steering wheel from stop-to-stop. Then turn the engine off and apply the brake pedal several more times to deplete accumulator pressure. Have them check fluid level and add if needed. If the fluid is foamy, tell them to let the vehicle stand for a few minutes and recheck fluid level. Let them know it may be necessary to repeat the process until all air is purged from the system.
2. With the wheels off the ground and the engine stopped, tell students to turn the steering wheel from stop-to-stop. Have them check fluid level and add if needed. Lower the vehicle.
3. Instruct students to repeat the first step, then start the engine and apply the brake pedal several times while turning the steering wheel from stop-to-stop. Have them turn the engine off and apply the brake pedal several more times to deplete accumulator pressure. Tell them to check fluid level and add if needed. If the fluid is foamy, inform them to let the vehicle stand for a few minutes and recheck fluid level. Let them know it may be necessary to repeat the process until all air is purged from the system.
Teach students that vehicles with hydraulically assisted power brakes will occasionally develop a problem where power steering fluid gets forced into the brake fluid. If this happens, explain that the entire hydraulic brake must be repaired. All rubber components which have come into contact with the oil/brake fluid mixture will swell and must be replaced. All metal components must be thoroughly flushed to remove the contamination.
Applications/Practice
Evaluation and feedback Prior to Testing or Lab Work
STUDENT ASSESSMENT:(Assess student progress with performance criteria.)
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.)