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Servo Unit

Technical Information

Catalogue No: C0833
Category: Flight Control
Object Type: Actuator
Object Name: Servo Unit
Part No: 96G19031
Serial No: 11384
Manufacturer: Harowe Servo Controls
Division: Unknown
Platform(s): Sentinel Airship
Year of Manufacture: circa 1992
Dimensions: Width (mm): 86
Height (mm): 86
Depth (mm): 125
Weight (g): 1,626
Location: Rack RAA02 [Main Store]

Harowe Servo Controls, Inc.
West Chester, PA
Harosyn-RCX, 21BRCX-500-J12, S/N 6252
Rotor(in) 4.25V. Stator9out) 2V. 7000Hz


The duplex actuator is an element in the optically signalled Flight Control System of the Skyship SKS 600 Airship and is required to move the control surfaces (two rudders and two elevators) in response to pilot commands input via the control yokes. It is mounted on the hinge line of the control surfaces. It incorporates two samarium cobalt DC Servo Units mounted on a common shaft, each with a separate power lane. One motor only is used to supply the torque and the second motor switched should there be a failure in the first lane. The motor shaft is part of a simple 3-stage epicyclic gear train designed to give a gear reduction of approximately 90:1 and hence a design running torque of approximately 1066Nm (72lb-ft) i.e. at half the max rated torque of a single motor. Provision is made for two slab tachometers mounted on the motor shaft, to give velocity feedback to each channel as part of the servo loop, if required. A 3-gang plastic-film potentiometer is mounted on the output shaft, two channels to give positional feedback information, one to each lane of the servo loop, and the third giving independent surface positional information.

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