Donald H Hockenberry

US Patent:

42070317, Jun 10, 1980

Filed:

Mar 29, 1978

Appl. No.:

5/891403

Inventors:

Alfred E. Maskrey - Pittsburgh PA
Donald H. Hockenberry - Trafford PA

Assignee:

Leybold-Heraeus GmbH & Co. KG - Cologne

International Classification:

F04D 4900

US Classification:

417 12

Abstract:

A dual speed mechanical rotary vacuum pump wherein a mechanical rotary vacuum pump is directly connected to a two speed electrical motor which drives the pump and the speed of the motor is controlled by an electrical control circuit which selectively causes the motor to rotate at either a first speed for a predetermined period of time or at a second slower speed. The speed of the motor is automatically switched to the slower speed after the predetermined period of time.