# Machine Dynamics Questions and Answers – Steam Engine Valves and Reversing Gears

This set of Machine Dynamics Quiz focuses on “Steam Engine Valves and Reversing Gears”.

1. In a steam engine, the distance by which the outer edge of the D-slide valve overlaps the steam port is called
b) steam lap
c) exhaust lap
d) none of the mentioned

Explanation: Steam lap is the distance by which the outer edge of the D-slide valve overlaps the steam port.

2. In a steam engine, the distance by which the inner edge of the D-slide valve overlaps the steam port is called lead.
a) True
b) False

Explanation: In actual practise, the displacement of the D-slide valve is greater than the steam lap by a distance known as lead of the valve.

3. The displacement of the D-slide valve is ______________ the steam lap by a distance known as lead of the valve.
a) greater than
b) less than
c) equal to
d) none of the mentioned

Explanation: In actual practise, the displacement of the D-slide valve is greater than the steam lap by a distance known as lead of the valve.

4. The D-slide valve is also known as
c) piston slide valve
d) none of the mentioned

Explanation: Since the steam is admitted from outside the steam chest, therefore, D-slide valve is also known as outside admission valve.

5. The piston slide valve is an inside admission valve.
a) True
b) False

Explanation: Since the steam enters from the inside of the two pistons, therefore, the piston valve is also known as inside admission valve.
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6. The distance by which the _____________ of the D-slide valve overlaps the steam port is called exhaust lap.
a) inner edge
b) outer edge
c) centre edge
d) none of the mentioned

Explanation: Steam lap or exhaust lap is the distance by which the outer edge of the D-slide valve overlaps the steam port.

7. Which of the following statement is correct?
a) The power absorbed in operating the piston valve is less than D-slide valve.
b) The wear of the piston valve is less than the wear of the D-slide valve.
c) The D-slide valve is also called outside admission valve.
d) all of the mentioned

Explanation: All the statements are correct.

8. The distance moved by the valve from one end to the other end is called valve travel.
a) True
b) False

Explanation: Valve travel is the distance moved by the valve from one end to the other end.

9. The throw of the eccentric is equal of the valve travel.
a) True
b) False

Explanation: The throw of the eccentric is equal to half of the valve travel.

10. 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
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 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.

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