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Shunt Motor with Inherent Holding Torque

IP.com Disclosure Number: IPCOM000092244D
Original Publication Date: 1968-Oct-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Scott, CB: AUTHOR [+2]

Abstract

Static holding torque is provided for a tape drive system by employing small amounts of higher hysteresis loss material in armature fabrication for the DC driving motor. In a tape drive, static tape tension tends to cause drifting of the tape reel, which can cause tape loop oscillation in the vacuum columns if the static friction in the tape path is not sufficient to overcome this tension. In the past, a small biasing current is introduced to the DC reel motors sufficient to stabilize a half-full reel with the static friction augmenting this to prevent drift for nearly full or nearly empty reels. However, for systems having extremely low static friction in the tape paths, this biasing technique is not always effective.

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Shunt Motor with Inherent Holding Torque

Static holding torque is provided for a tape drive system by employing small amounts of higher hysteresis loss material in armature fabrication for the DC driving motor. In a tape drive, static tape tension tends to cause drifting of the tape reel, which can cause tape loop oscillation in the vacuum columns if the static friction in the tape path is not sufficient to overcome this tension.

In the past, a small biasing current is introduced to the DC reel motors sufficient to stabilize a half-full reel with the static friction augmenting this to prevent drift for nearly full or nearly empty reels. However, for systems having extremely low static friction in the tape paths, this biasing technique is not always effective.

DC drive motors used for the reels are fabricated from low hysteresis iron. Therefore, the fabrication of DC reel motors by including controlled amounts of high hysteresis loss material in their armatures provides a small amount of static holding torque at the expense of a fraction of the normal operating torque. One method of achieving this is to fabricate the motor from armature laminations of higher hysteresis loss material than usual. Another arrangement is to include selected laminations of high hysteresis loss material with the other laminations of state of the art, low loss material. Yet another alternative is to utilize high loss material at one end of the armature without cutting slots for the coppe...