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Suggested Specifications – Group 11 Rotary Damper Drives and Actuators

Basic Drive Unit

Control drive shall have integrated electronics and be able to operate in ambient temperatures of -40°F. (-40°C.) to 185°F. (85°C.).

The drive shall be furnished with a 120 volt AC, single phase, __ (50 or 60) Hz, synchronous motor. Motor shall be capable of withstanding continuous modulating duty (60 starts / stops per minute at a minimum) or a stall condition without overheating. Design of the motor shall be such that electrical and thermal overloads are not required.

Motor bearings shall be maintenance-free. Motor shall be non-coasting with instant magnetic braking, and shall be self-locking and self-releasing without the use of a separate brake winding, mechanical brake or worm gear mechanism. Control drive shall be designed to stay in place upon loss of power and shall be capable of holding a load equal to at least 200% of the model’s rated output. The drive motor shall be a TENV with Class H insulation.

Control drive shall be rated for ____lb-ft torque output. Stall torque shall be self-limiting, not exceeding two and one half times the rated torque; torque switches shall not be required. Drive shall operate ___ (CW or CCW) on increasing signal, with timing of __ seconds for full 100° rotation. Gear train shall have high efficiency spur gears constructed of heat treated alloy steel or ductile iron only. Readily available gear modules shall provide for a range of torque and timing combinations within the drive’s rated capacity, and shall be field-interchangeable. Drive train parts shall be lubricated with a premium, heavy-duty lithium-based lubricant. No oil baths shall be used for lubrication. Control drives shall be able to operate in any mounting orientation.

Two SPDT over-travel limit switches shall be provided for over-travel protection. In addition, the drive shall have ____ (none, two, four) auxiliary SPDT switches which are infinitely adjustable over the full range of travel. Switches shall be rated for 6 amps at 120 volts AC. Drive shall have integral mechanical stops capable of limiting travel of the drive and load, with or without the drive motor.

A low-speed, disc-type motor Handwheel shall permit manual operation of the drive without electrical power and without a declutching mechanism.


A five-position, drive-mounted electric Handswitch shall be provided to permit local electrical operation of the unit for control adjustment or operation on loss of control signal. With the Handswitch in AUTO mode, drives shall respond to control signals automatically.

Enclosure shall be totally enclosed, cast, weatherproof, dust-tight, NEMA 4X construction. All field connections shall be made at one terminal compartment. Separate conduit entrances shall be available for power and control wiring.


Modulating mA or V dc Analog Control Input

Drive shall provide modulating control through an integral, digital control module which positions the drive in proportion to the (___ mA range or ___ V dc range) control input signal.


The control module shall be capable of initiating shaft movement in steps down to 0.1°.

Standard control features should include:

  • Field-configurable, pre-determined action upon loss of input signal
  • Stall protection
  • Split signal operation for control of multiple drives
  • External position feedback signal

Modulating Direct AC Control

Drive shall be operated by direct AC control power either from an automatic controller or by manually operated switches, with continuous positioning capability over the range of operation. Drive shall be capable of starting and stopping instantaneously for high-resolution positioning.

Multi-Position Direct AC Control

Drive shall provide ___ (3 to 6) discrete positions upon closure of an automatic controller or by manually operated switches, with provision for adjustable predetermined position settings, and have a positioning repeatability of 0.1% over the range of operation.

Open/Close Direct AC Control

Drive shall provide open / close operation to preset travel limits upon closure of an automatic controller or by a manually operated switch, and have a 0.1% position repeatability, with end-of-travel limits adjustable over the full range of travel of the drive.

Position Feedback Specification

Drive shall be equipped with a contactless position sensing device and be capable of providing an isolated feedback signal with a 4–20 mA or 1–5 V dc range. The sensing device shall have infinite resolution.