TB 48 Jacobs Engine Brake

Question 1

Diesel engines have ____ retarding effect upon vehicles than a gasoline engine.

Answer 1

substantially less

Question 2

This is due to lack of ___ in the diesel intake manifold.

Answer 2

restriction

Question 3

The gasoline engine has a ___ in the carburetor which creates a vacuum and subsequent engine braking.

Answer 3

butterfly

Question 4

The Jacobs Engine Brake is a hydraulic engine attachment that, when energized, alters the engine ____ operation which converts the diesel engine into an air compressor.

Answer 4

exhaust valve

Question 5

This is accomplished by prematurely opening the exhaust valves near the top of the ____ stroke releasing the compression pressure to exhaust.

Answer 5

compression

Question 6

The engine brake reacts quickly. It will activate or deactivate in less than ___ of a second.

Answer 6

1/4

Question 7

The Jake Brake switches used on an apparatus equipped with a manual shift transmission and a Cummins Diesel engine, will be an on-off switch mounted on the ___.

Answer 7

gear shift lever.

Question 8

Cummins with Manual:
A three (3) position switch controlling the amount of retarding power desired, mounted on the \_\_\_, and two (2) additional switches, one mounted on the \_\_\_ and the other mounted on the \_\_\_.

Answer 8

dash board / clutch pedal / throttle pedal

Question 9

Cummins with auto trans:

The Jake Brake switches will be on ON/OFF switch mounted on the ____.

Answer 9

dash board

Question 10

Cummins with auto trans:
A three position switch controlling the amount of retarding power desired, mounted on the dash board, a throttle pedal switch which de-activates the jake brake if depressed, and a pressure sensing switch mounted on the transmission to de-activate the jake brake at ______.

Answer 10

low speeds

Question 11

Detroit Diesel with auto trans:
The Jake Brake switches used on an apparatus equipped with an automatic transmission and a Detroit Diesel engine, will be a ____ switch, ______, mounted on the dash board.

Answer 11

single, three position /

off-low-high

Question 12

Detroit Diesel with auto trans:
There is also a throttle pedal switch which deactivates the Jake Brake when depressed, and a pressure sensing switch mounted on the transmission to de-activate the Jake Brake at ___.

Answer 12

low speeds

Question 13

Medium Traffic Conditions

Answer 13

Minimum to moderate Jake brake setting

Question 14

Heavy Traffic Conditions and Emergency Responses

Answer 14

Maximum Jake Brake switch setting

Question 15

Wet street operations

Answer 15

Do not engage on wet streets, could cause uncontrollable skid

Question 16

When accelerating the apparatus, ___ using the Jake Brake. (i.e. shift from first gear to second gear, second to third gear, etc.) This could cause abnormal stresses and shock loads to the engine and may lead to engine damage.

Answer 16

DO NOT UPSHIFT

Question 17

Do not ride the clutch pedal to disengage the jake brake. this was cause ____ to the throw out bearing, clutch and thrust bearing on the crankshaft

Answer 17

premature wear

Question 18

Do not engage the jake brake at idle or low engine speed, will cause engine too ___

Answer 18

stall.