Common mechanical transmissions include leadscrews, rack & pinion
mechanisms,
conveyors, gears, and timing belts. The use
of leadscrew, rack & pinion, or
conveyor are common ways to translate the rotary motion
of the servo motor
into linear motion of the load.
The use of a speed reducer such as a gearbox or timing
belt can be very
beneficial as follows:
As a general rule, it is beneficial
to keep the reflected load inertia as low as possible
while using the full range of servo speed. SureServo™ systems
can go up to 5,000 rpm for the low inertia motors
and up to 3,000 rpm for the medium inertia motors.
However, when investigating
the effect of different speed reduction ratios
DO NOT forget to include the added inertia of couplings,
gearbox, or timing belt pulleys. These added inertias
can be significant and can totally undo any inertia
reduction due to the speed reduction. |
If the application requires
low speed and high torque then it is common to introduce
a speed reducer so that the servo system can operate
over more of the available speed range. This could
also have the added benefit of reducing the servo
motor torque requirement which could allow you to
use a smaller and lower cost servo system.
Additional benefits are also
possible with reduction in reflected inertia, increased
number of motor encoder counts at the load, and
increased ability to reject load disturbances due
to mechanical advantage of the speed reducer. |
Reducers can possibly allow
the use of a smaller motor or allow the motor to
be repositioned. For example, some reducers would
allow for in-line, right angle, or parallel mounting
of the motor. |
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