TB #48 JACOBS ENGINE BRAKE

Question 1

DIESEL ENGINES HAVE A SUBSTANTIALLY LESS RETARDING EFFECT UPON VEHICLES THAN A GASOLINE ENGINE

TRUE/FALSE

Answer 1

TRUE
(THIS IS DUE TO LACK OF RESTRICTION IN THE DIESEL INTAKE MANIFOLD)

Question 2

THE JACOBS ENGINE BRAKE IMPROVES ENGINE RETARDING BY PREMATURELY OPENING THE EXHAUST VALVES NEAR THE ___ OF THE COMPRESSION STROKE, RELEASING THE COMPRESSION PRESSURE TO EXHAUST.

Answer 2

TOP

Question 3

THE JACOBS ENGINE BRAKE REACTS QUICKLY. IT WILL ACTIVATE OR DEACTIVATE IN LEASS THAN ___ OF A SECOND.

Answer 3

1/4

Question 4

THE JAKE BRAKE SWITCHES USED ON AN APPARATUS EQUIPPED WITH A MANUAL SHIFT TRANSMISSION AND A CUMMINS DIESEL ENGINE WILL BE…

Answer 4

1. ON-OFF SWITCH (MOUNTED ON GEAR SHIFT LEVER)
2. (3) POSITION SWITCH, CONTROLLING AMOUNT OF RETARDING POWER
3. ONE MOUNTED ON CLUTCH PEDAL
4. ONE MOUNTED ON THROTTLE PEDAL

Question 5

THE JAKE BRAKE SWITCHES USED ON AN APPARATUS EQUIPPED WITH AN AUTOMATIC TRANSMISSION AND A CUMMINS DIESEL ENGINE WILL BE…

Answer 5

1. ON-OFF SWITCH
2. (3) POSITION SWITCH, CONTROLLING AMOUNT OF RETARDING POWER
3. THROTTLE PEDAL SWITCH, WHICH DE-ACTIVATES THE JAKE BRAKE IF DEPRESSED
4. PRESSURE SENSING SWITCH MOUNTED TO TRANSMISSION, WHICH DE-ACTIVATES THE JAKE BRAKE AT LOW SPEEDS

Question 6

THE JAKE BRAKE SWITCHES USED ON AN APPARATUS EQUIPPED WITH AN AUTOMATIC TRANSMISSION AND A DETROIT DIESEL ENGINE WILL BE…

Answer 6

1. A SINGLE, THREE POSITION SWITCH, “OFF-LOW-HIGH”

Question 7

ACCORDING TO TB #48, DO NOT ENGAGE THE JAKE BRAKE ON ___ STREETS. THE ADDITIONAL BRAKING EFFORT ON THE DRIVE WHEELS (DUALS) CAN CAUSE THEM TO LOCK UP WHICH COULD RESULT IN AN UNCONTROLLABLE SKID

Answer 7

WET

Question 8

ACCORDING TO TB #48, DO NOT ENGAGE THE JAKE BRAKE DURING _______ OR _______ OPERATIONS.

Answer 8

PUMPING OR AERIAL OPERATIONS