Simple Mechanisms

Question 1
Marks : +2 | -2
Pass Ratio : 100%
The motion of a piston in the cylinder of a steam engine is an example of
completely constrained motion
incompletely constrained motion
successfully constrained motion
none of the mentioned
Explanation:
The piston and cylinder in a steam engine form a pair and the motion of the piston is limited to a definite direction (i.e. it will only reciprocate) relative to the cylinder irrespective of the direction of motion of the crank.
Question 2
Marks : +2 | -2
Pass Ratio : 100%
The mechanism forms a structure, when the number of degrees of freedom (n) is equal to
0
1
2
– 1
Explanation:
When n = 0, then the mechanism forms a structure and no relative motion between the links is possible.
Question 3
Marks : +2 | -2
Pass Ratio : 100%
The cam and follower without a spring forms a
lower pair
higher pair
self closed pair
force closed pair
Explanation:
When the two elements of a pair are connected together mechanically in such a way that only required kind of relative motion occurs, it is then known as self closed pair. The lower pairs are self closed pair and the motion of cam and follower is relative to each other.
Question 4
Marks : +2 | -2
Pass Ratio : 100%
When the elements of the pair are kept in contact by the action of external forces, the pair is said to be a
lower pair
higher pair
self closed pair
force closed pair
Explanation:
When the two elements of a pair are not connected mechanically but are kept in contact by the action of external forces, the pair is said to be a force-closed pair. The cam and follower is an example of force closed pair, as it is kept in contact by the forces exerted by spring and gravity.
Question 5
Marks : +2 | -2
Pass Ratio : 100%
In a 4 – bar linkage, if the lengths of shortest, longest and the other two links are denoted by s, l, p and q, then it would result in Grashof’s linkage provided that
l + p < s + q
l + s < p + q
l + p = s + q
none of the mentioned
Explanation:
None
Question 6
Marks : +2 | -2
Pass Ratio : 100%
The lead screw of a lathe with nut forms a
sliding pair
rolling pair
screw pair
turning pair
Explanation:
When the two elements of a pair are connected in such a way that one element can turn about the other by screw threads, the pair is known as screw pair. The lead screw of a lathe with nut, and bolt with a nut are examples of a screw pair.
Question 7
Marks : +2 | -2
Pass Ratio : 100%
Which of the following is an inversion of double slider crank chain ?
Coupling rod of a locomotive
Pendulum pump
Elliptical trammels
Oscillating cylinder engine
Explanation:
A kinematic chain which consists of two turning pairs and two sliding pairs is known as double slider crank chain and elliptical trammels are such pairs.
Question 8
Marks : +2 | -2
Pass Ratio : 100%
Which of the following is a turning pair ?
Piston and cylinder of a reciprocating steam engine
Shaft with collars at both ends fitted in a circular hole
Lead screw of a lathe with nut
Ball and socket joint
Explanation:
When the two elements of a pair are connected in such a way that one can only turn or revolve about a fixed axis of another link, the pair is known as turning pair. A shaft with collars at both ends fitted into a circular hole, the crankshaft in a journal bearing in an engine, lathe spindle supported in head stock, cycle wheels turning over their axles etc. are the examples of a turning pair.
Question 9
Marks : +2 | -2
Pass Ratio : 100%
The motion transmitted between the teeth of gears in mesh is
sliding
rolling
may be rolling or sliding depending upon the shape of teeth
partly sliding and partly rolling
Explanation:
When the two elements of a pair have a line or point contact when relative motion takes place and the motion between the two elements is partly turning and partly sliding, and in mesh the gears have a point contact.
Question 10
Marks : +2 | -2
Pass Ratio : 100%
The Grubler’s criterion for determining the degrees of freedom (n) of a mechanism having plane motion is
n = (l – 1) – j
n = 2 (l – 1) – 2j
n = 3 (l – 1) – 2j
n = 4 (l – 1) – 3j
Explanation:
The Grubler’s criterion applies to mechanisms with only single degree of freedom joints where the overall movability of the mechanism is unity.