Simple Mechanisms

Question 1
Marks : +2 | -2
Pass Ratio : 100%
In a four bar chain or quadric cycle chain
each of the four pairs is a turning pair
one is a turning pair and three are sliding pairs
three are turning pairs and one is sliding pair
each of the four pairs is a sliding pair.
Explanation:
A very important consideration in designing a mechanism is to ensure that the input crank makes a complete revolution relative to the other links. The mechanism in which no link makes a complete revolution will not be useful. In a four bar chain, one of the links, in particular the shortest link, will make a complete revolution relative to the other three links, if it satisfies the Grashof ’s law. Such a link is known as crank or driver.
Question 2
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 3
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 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%
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 6
Marks : +2 | -2
Pass Ratio : 100%
A ball and a socket joint forms a
turning pair
rolling pair
sliding pair
spherical pair
Explanation:
When the two elements of a pair are connected in such a way that one element (with spherical shape) turns or swivels about the other fixed element, the pair formed is called a spherical pair, and ball and socket joint are such pairs.
Question 7
Marks : +2 | -2
Pass Ratio : 100%
If n links are connected at the same joint, the joint is equivalent to
(n – 1) binary joints
(n – 2) binary joints
(2n – 1) binary joints
none of the mentioned
Explanation:
In general, when n number of links are joined at the same connection, the joint is equivalent to (n – 1) binary joints.
Question 8
Marks : +2 | -2
Pass Ratio : 100%
In a kinematic chain, a quaternary joint is equivalent to
one binary joint
two binary joints
three binary joints
four binary joints
Explanation:
When four links are joined at the same connection, the joint is called a quaternary joint. It is equivalent to three binary joints.
Question 9
Marks : +2 | -2
Pass Ratio : 100%
In a reciprocating steam engine, which of the following forms a kinematic link ?
cylinder and piston
piston rod and connecting rod
crank shaft and flywheel
flywheel and engine frame
Explanation:
in a reciprocating steam engine, piston, piston rod and crosshead constitute one link ; connecting rod with big and small end bearings constitute a second link ; crank, crank shaft and flywheel a third link and the cylinder, engine frame and main bearings a fourth link.
Question 10
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.