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Power Transfer Mechanisms
There is a need for mechanisms to change the high speed/low torque on the motor output shaft
into the low speed/high torque required for most applications.
There are various power transfer mechanisms.
Some are attached directly to the motor; some require separate shafts and mounts between the motor and
the output shaft; and still others couple the motor to the output shaft directly.
In those power transfer
methods that require attaching one shaft to another, such as motor-mounted gearboxes driving a separate
output shaft, shaft couplers and flexible drives are used to deal with misalignment and vibration. The
solid shaft couplers must be strong enough to hold the shafts` end together as if they were one shaft.
The flexible couplers allow for misalignment and are used where the two shafts might be slightly out of alignment.
These couplers have different diameters and end details such as splined, keyed, hex, square or smooth according
to the shafts they are coupling.
More information on spline shafts.
To protect the power transfer mechanism against overloading when the shock loads are high,
torque limiters and clutches are used.
Introduction to Gears
Gears are the most common indirect power transmission method. The advantages are:
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Gears can be scaled to transmit power from small battery powered watch motors up to the power from thousand
horseower gas turbine engines.
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Gears transmit powe efficiently, smoothly and quietly when they are properly mounted and lubricated.
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Gears can transmit power between shafts in parallel, intersecting and also skewed.
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Gears change rotational speed, direction, angular orientation of rotational motion, multiply or divide
the torque, convert rotational to linear motion and vice versa, and offset or change the location
of rotation motion.
Gears are available as spur, helical, double helical, bevel, spiral bevel, miter, face, hypoid, rack,
straight worm, double enveloping worm, and harmonic. Each type has its own pros and cons, includig differences
in efficiency, allowable ratios, mating shaft angles, noise and cost.
More information on gears manufacturing, gears geometry and types.
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