# Machine Dynamics Questions and Answers – Reversing Gears

This set of Machine Dynamics Multiple Choice Questions & Answers (MCQs) focuses on “Reversing Gears”.

1. In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve may be obtained by increasing the angle of advance of the eccentric but reducing the throw of the eccentric and keeping the steam lap and exhaust lap constant. The method will cause withdrawing or throttling of steam.
a) True
b) False

Explanation: In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve is by increasing the angle of advance of the eccentric while the throw of the eccentric, steam lap and exhaust lap are kept constant. The method will reduce length of effective stroke of piston.
In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve may be obtained by increasing the angle of advance of the eccentric but reducing the throw of the eccentric and keeping the steam lap and exhaust lap constant. The method will cause withdrawing or throttling of steam.

2. In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve is by increasing the steam lap and the angle of the eccentric but keeping constant the travel and lead of the valve. This method will
a) cause withdrawing or throttling of steam
b) reduce length of effective stroke of piston
c) reduce maximum opening opening of port to steam
d) all of the mentioned

Explanation: In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve is by increasing the steam lap and the angle of the eccentric but keeping constant the travel and lead of the valve. This method will reduce maximum opening opening of port to steam.
In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve is by increasing the angle of advance of the eccentric while the throw of the eccentric, steam lap and exhaust lap are kept constant. The method will reduce length of effective stroke of piston.
In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve may be obtained by increasing the angle of advance of the eccentric but reducing the throw of the eccentric and keeping the steam lap and exhaust lap constant. The method will cause withdrawing or throttling of steam.

3. In Meyer’s expansion valve, the main valve is driven by an eccentric having and angle of advance from
a) 100-150
b) 150-250
c) 250-300
d) 300-400

Explanation: In Meyer’s expansion valve, the main valve is driven by an eccentric having and angle of advance from 250-300 and the expansion valve is driven by an eccentric having angle of advance 800-900.

4. The virtue or equivalent eccentric for the Meyer’s expansion valve is defined as an eccentric having such a length and angle of advance that will cause cut-off to take place at the same position, as is caused by the combined effect of main eccentric and expansion eccentric.
a) True
b) False

Explanation: None

5. In Meyer’s expansion valve, the expansion valve is driven by an eccentric having an angle of advance from
a) 500-600
b) 600-700
c) 700-80
d) 800-900

Explanation: In Meyer’s expansion valve, the main valve is driven by an eccentric having and angle of advance from 250-300 and the expansion valve is driven by an eccentric having angle of advance 800-900.

6. The function of a reversing gear in a steam engine is
a) to control the supply of steam
b) to alter the point of cut-off while the engine is running
c) to reverse the direction of motion of the crank shaft
d) both b and c

Explanation: The function of a reversing gear in a steam engine is to alter the point of cut-off while the engine is running and to reverse the direction of motion of the crank shaft.

7. When the load on the engine increases, it becomes necessary to increase the supply of working fluid and when the load decreases, less working fluid is required. The supply of the working fluid to the engine is controlled by a
a) D-slide valve
b) governor
c) Meyer’s expansion valve
d) flywheel

Explanation: When the load on the engine increases, it becomes necessary to increase the supply of working fluid and when the load decreases, less working fluid is required. The supply of the working fluid to the engine is controlled by a governor.
Flywheel controls the speed variation caused by the fluctuations of the engine turning moment during each cycle of operation.

8. A flywheel is used to control the mean speed of an engine caused by the variations in load.
a) True
b) False

Explanation: The function of a governor is to regulate the mean speed of an engine caused by the variations in load.

9. Which of the following is used to control the speed variations of the engine caused by the fluctuations of the engine turning moment?
a) D-slide valve
b) Governor
c) Flywheel
d) Meyer’s expansion valve

Explanation: The function of a governor is to regulate the mean speed of an engine caused by the variations in load.
Flywheel controls the speed variation caused by the fluctuations of the engine turning moment during each cycle of operation.

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