Westinghouse Electric Corporation

Andrew P Kruper

Frederick O Johnson

Joachim E Wolf

Charles W Maiden

A transportation apparatus having improved brake control. The actual speed of the transportation apparatus is compared with a reference speed signal, and when the actual speed exceeds the reference speed a brake is applied to slow the transportation apparatus. Rather than simply applying the full torque of the brake abruptly, the present invention discloses an apparatus for pulse duration modulating the control signal for controlling the brake. The brake responds to the average of the pulse duration modulated control signal such that braking torque is applied gradually and essentially linearly. The device can also be used in an acceleration situation to provide gradual acceleration of the transportation apparatus.

Conveyor brake control

An adjustable time delay relay is provided which is particularly suitable for automatic transfer switches and other applications requiring a relatively long time delay during periods when electrical power is not available. The relay includes a relay coil connected across a large storage capacitor supplied from an AC power source through a diode. The timing function is provided by a separate timing capacitor which, upon discharge through an associated adjustable resistor, operates a switching transistor to establish a low impedance path across the relay coil, thus discharging the storage capacitor and de-energizing the relay. Such a construction eliminates the need for a close tolerance, high value storage capacitor and provides a high degree of time delay reproducibility despite variations in power supply voltage.

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Penn Hills, PA, United States of America

Andrew P Kruper