Inspect engine compression/exhaust brake housing, valves, seals, lines, and fittings; determine needed action.

Lesson Plan for

DIT 112 Diesel Engines

Course HS Title: / Diesel Engines / Program:
KCTCS Courses included in HS Title: (Lesson is prepared for course highlighted.)
KCTCS Course No. / KCTCS Course Title
DIT 112 / Diesel Engines
Introduction/Context / This lesson will instruct the student on how to inspect engine compression/exhaust brake housing, valves, seals, lines, and fittings, and determine needed 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 a Diesel 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 engine compression/exhaust brake housing, valves, seals, lines, and fittings; determine needed action.
Objective
Given the proper tools and instruction, the student will be able to inspect engine compression/exhaust brake housing, valves, seals, lines, and fittings, determine needed 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
N-Q-1

INSTRUCTIONAL MATERIALS/TECHNOLOGY

Teacher Designed Materials and Other Handouts


Textbooks and Workbooks

Author / Title/ISBN No. / Edition / Publisher / Pages
Various / Diesel Engines ASE Test Prep / Fourth / Delmar / 72


Equipment

Quantity / Item / Source
As Needed / Scan Tool / Various


Content/Presentation/Demonstration Outline

Tell students that engine brakes on many older hydro-mechanical engines were quite often an aftermarket addition, and in most cases not manufactured by the engine manufacturer. These units were bolted to the rocker housing and raised the overall height of the engine. Aftermarket internal engine compression brakes were engine specific. In each, the timing of the effective cycle of the engine brake was triggered by movement of either a valve or injector rocker arm.
Explain that Caterpillar and Mack engines equipped with Jacobs brakes used valve rocker arm movement on an adjacent cylinder to trigger the opening of the exhaust valves over the cylinder being braked, while Detroit Diesel MUI and Cummins PT used movement of the injector rocker to actuate the hydraulic circuit responsible for opening the exhaust valves.
Tell students that Mack Dynatard was a built-in system that used the same general principles of operation as the Jacobs brake, but actuated the opening of the exhaust valves using cam geometry. In all these systems, setting the top end of the engine must be done consulting both the OEM and brake manufacturer’s service literature. Let them know that on some of these hydro-mechanical systems, engine braking could be hard on the valve trains and camshafts. Although the brake assembly hardware and hydraulics seldom failed, the camshaft and valve or injector trains failed.
Instruct students that many current engines continue to use add-on Jacobs brakes, but the management of braking effective cycles is now a responsibility of the ECM. In recent years, tell them that double-cycle engine brakes have been introduced. These use engine braking on both upward strokes of the piston. The compression braking requires the dumping of cylinder pressure at the completion of the compression stroke, and exhaust braking is accomplished by choking off exhaust flow outside of the engine cylinder.
Inform them that some current engine manufacturers use their own built-in engine brakes, completely managed by the engine management system. The Cummins Signature ISX provides six levels of engine braking, selectively using between one to six engine cylinders depending on the braking required. Tell them that diagnosis of engine brake problems on current engines must be performed by using the OEM electronic diagnostic procedures.
Instruct students that engine brakes typically use electric control switches, which may be actuated either directly by the driver or by the engine management ECM in “smart” cruise applications. Explain that when engine brakes are used in hydro-mechanically managed engines, the switching of the engine brake is usually electrical, but the retarding effect must be actuated either hydraulically or pneumatically In such engines, a control circuit would require that a series of switches be closed before engine braking can be effected.
Tell them that the first of this series of switches would be the driver control switch, which can be proportional depending on the system. The next would be located at the clutch. Explain that this must be necessarily fully engaged to operate engine braking. The final essential switch in the series (though any number of others may be installed) would be to ensure that the accelerator was not depressed, in other words, engine fueling is at zero (current engines) or at least at a minimum in older engines to limit the quantity of raw fuel dumped into the exhaust system.
Inform them that current regulations require that no uncombusted fuel is discharged into the exhaust system so the rules of operation have changed in recent years. However, tell them that engine brakes used in many current engines are managed/monitored by the engine electronics. When an engine brake is electrically switched to the on position, the result depends on the type of engine brake used. Some of the common engine brakes are described here.
Instruct students that Williams exhaust brakes are classified as external engine compression brakes. Control of the brake is electric over pneumatic Explain that the electrical circuit required to actuate the engine brake consists of three switches all of which must be closed a control switch (dash mounted), a clutch switch (clutch must be fully engaged), and an accelerator switch (accelerator must be at zero travel).
Tell them that the sliding gate exhaust brake uses a pneumatically activated gate, actuated by chassis system pressure. The air supply to close the gate is controlled by an electrically switched pilot valve. Let them know that an aperture in the sliding gate permits a minimal flow through the brake gate during engine braking. The butterfly valve version operates similarly.


Applications/Practice

1 / Refer to content


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 will 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.)