Variable speed drives with or without reducer
VARMEC Variators are avaible in 7 sizes (VAR 2-5-10-20-30-5-75) with
speed range ratio of 5:1. Each size is avaible as either variators
only or as a combined variator and gear reducer of 1 or 2 reduction
stages in a single monolithic casing. Variators can be supplied complete
with IEC motors (B5 type).
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Output speed is changed progressively by operation of the control
handwheel which is provided with a direct speed position readout.
When required, the control handwheel can be replaced with an electric
servomotor with a limit switch device. Also, each variator can be
supplied with a proximity sensor to provide a display of output
speed on a digital gauge. Additionally, a digital or analogue converter
can be supplied to control the output speed from an external signal.
The VARMEC variable speed trasmission system is based on the transfer
of power, by friction, between the friction cone (1) mounted on
the motor shaft and the friction ring (2) mounted on the transmission
shaft. Pressure between the friction cone and the friction ring
is maintained in proportion to the output load torque by means of
the dog-clutch cam faces (4).
A spring (3) inside the concentric transmission shaft provides
a low contact pressure between the cone and the ring during no-load
or idling periods. This allows speed setting changes to be made
whilst stationary, this being a major advantage over other types
of variable speed drives, speed variation is achieved by movement
of the motor, on guides, by a rack (7) and pinion (6) attached to
the control handwheel, or alternatively by an electric speed control
system.
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