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Type of Couplings
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There are two
basic classes of couplings:-
1. Rigid Coupling
2. Flexible Couplings
Rigid Slip Couplings
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Rigid Coupling
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This type of coupling has no flexibility or
resilience, hence it is necessary for the shafts that are to be connected to be
in good alignment, both laterally and angularity, in order excessive loads on
the coupling, on the shafts, or on the shaft bearings.
Rigid couplings do not accommodate misalignment and
consequently should not be used indiscriminately. |
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Types of Rigid
Couplings:-
1.1 Sleeve or muff coupling
1.2 Clamp coupling
1.3 Flange coupling
1.1 Sleeve or muff coupling
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Sleeve or Muff Coupling
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It is the simplest type of rigid coupling, made of cast iron. It
consists of a hollow cylinder whose inner diameter is the same as
that of the shaft. It is fitted over the ends of the two shafts by means of a
gib head key. The power is transmitted from one haft to the other shaft by means
of a key and a sleeve. It is, therefore, necessary that all the elements
must be strong enough to transmit the torque. |
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1.2 Clamp coupling
Clamp
coupling is sometimes called a compression coupling or a ribbed coupling. Clamp
coupling is a modification and a improvement of the sleeve coupling. This
coupling is made in two parts which are machined to fit the shaft and are
finished off around the periphery and on both ends. The two halves of the
coupling are clamped tightly against the surface of the shaft ends by through
bolts and the entire torsional moment is transmitted entirely by friction.
1.3 Flange coupling
A flange coupling usually applies to a coupling having two separate cast
iron flanges. Each flange is mounted on the shaft end and keyed to it. The faces are turned up at right angle to the axis of the shaft. One of the flange has a
projected portion and the other flange has a corresponding recess. This helps to bring the
shafts into line and to maintain alignment. The
two flanges are coupled together by means of bolts and nuts. The flange coupling is adopted to
heavy loads and hence it is used on large
shafting. The flange couplings are of the following types:-
a) Unprotected type flange coupling
b) Protected type flange coupling
c) Marine type flange coupling
a) Unprotected type flange coupling:- In an unprotected type flange coupling each shaft is keyed to the boss of a flange with a
counter sunk key, and the flange are coupled together by means of bolts. Generally, three, four or six bolts are used. The keys
are staggered at right angle along the circumference of the shafts in order to divide the weakening effect caused by key ways.
b) Protected type flange coupling:- In a protected type flange coupling the protruding bolts and nuts are protected by flanges
on the two halves of the coupling, in order to avoid danger to the workman.
c) Marine type flange coupling:- In a marine type flange coupling, the flanges are forged integral with the
shafts. The
flanges are held together by means of tapered headless bolts numbering from four to
twelve depending upon the diameter of shaft.
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