There are a number of definitions and interpretations
of the term "Torque Motors". However a Torque Motor can be most readily
identified as an Induction motor which specifies starting (stalling) torque on the
nameplate. Also on the nameplate are the stall amperes and the synchronous speed. As a
rule, Torque Motors have very high slip characteristics as indicated by the curves &
are capable of providing maximum starting (stalling) torque with minimum input power.
A standard squirrel-cage motor tries to maintain the speed as it is being
loaded while the Torque Motor will drop in speed as it is loaded.
Also by changing the input voltage of the Torque Motor we can change the maximum
torque available at the shaft.
At any voltage if the load on the Torque Motor is removed it tries to accelerate to
the synchronous speed.
Following materials can be wound with the help of Torque motors.
Very thin plastic films; Thick plastic sheets; Webs; HDPE tape; monofilament yarn;
PVC sheets; Hessian; plastic pipes; Textiles (from light material to heavy coated,
impregnated fabrics); Rubber (thin sheeting, rubberised fabrics); Paper (thin, delicate,
perforated); Metal foil and strips; Very fine Copper wires, Copper strips etc.
Torque Motor offers braking torque when its rotor is driven against its normal
direction of rotation when energised. This characteristic is used to provide back tension
in winding cycle.
'Mark' make TORQUE MOTOR is a precision designed brush-less induction motor of
robust construction and is noted for its reliability under the worst operating conditions.
Generally smaller capacity motors are available in TESC & TEFC enclosures. Motors
of 100 Kg-cms Torque and above are screen protected and cooled with blowers. Foot and
Flange mounted constructions available as per IS Frames.
Torque Motors are rated in output torque at locked rotor (shaft) conditions.
'Mark' Torque Motors are available from shaft locked torque of 10 oz-in (0.7 Kg-cm) to 541
lb-ft (750 Kg-cms). Except smaller frames (63 & 71 Frames) these motors are available
in 2,4, 6, 8 & 12 pole designs. Two & Three-Speed Torque Motors can be specially
designed as per requirements.