Shared about Couplings which are devices used to connect two shafts together.

1. Couplings and its facts
What is it?
Coupling is a device that connects two shafts together at their ends with the purpose of transmitting
power. They normally do not allow disconnection of shafts during operation, however there is torque
limiting them which can slip or disconnect when some torque limit is exceeded.
To join two pieces of rotating equipment while permitting some degree of misalignment or end
movement or both is the couplings primary purpose. By careful selection, maintenance and of
installation them, substantial savings can be made in reduced maintenance costs and downtime.
What is gear coupling?
It is a mechanical device for transmitting torque between two shafts that are not collinear. It consists of
a flexible joint fixed to each shaft. The two joints are connected by a third shaft, called the spindle.
Gear couplings are generally limited to angular misalignment, i.e., the angle of the spindle relative to the
axes of the connected shafts, of 4-5°. Universal joints are capable of higher misalignment.
Single joint gear couplings are also used to connect two nominally coaxial shafts. In this application the
device is called a gear-type or flexible coupling. The single joint allows for minor misalignment such as
installation errors and changes in shaft alignment due to operating conditions. These types of gear
couplings are generally limited to angular misalignment of 1/4-1/2°.
It is generally observed that even with the most exacting precision in the original installation,
subsequent misalignment can rarely be avoided over a period of time, foundations may settle, bearings
ultimately wear and dimensions change with temperature.
The misalignment also takes place due to vibrations. These Flexible Gear couplings are available in two
configurations - Full Geared and Half Geared Half Rigid.
Full Geared Coupling: Here both the halves are identical and consist of two Hubs and two outer Flanges
Sleeves bolted together. This type of Coupling is capable of accommodating both Offset as well as
Angular misalignment.
Half Geared Half Rigid Coupling: Here instead of two identical halves one half is geared and the other
half is rigid. There is a single Hub in this type since the other side is rigid. This type is used for taking care
of only Angular misalignment.