US PATENT SUBCLASS 91 / 16
.~ Drifting or coasting on lower pressure

Current as of: June, 1999
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91 /   HD   MOTORS: EXPANSIBLE CHAMBER TYPE

6  DF  FLUID SUPPLY THROUGH DIVERSE PATHS TO SINGLE EXPANSIBLE CHAMBER {12}
16.~ Drifting or coasting on lower pressure {2}
17  DF  .~.~> With speed responsive cutoff of drifting fluid
18  DF  .~.~> Pressure control of drifting fluid

DEFINITION

Classification: 91/16

(under subclass 6) Apparatus in which the working chamber is supplied with relatively high pressure fluid to drive the working member and is supplied with a relatively lower pressure fluid when the high pressure fluid is cut off and the motor is coasting (i.e., being driven by the load) to prevent vacuum build-up in the working chamber.

(1) Note. This is an art group in which the momentum of the load (e.g., locomotive) drives the motor working member after the motive fluid has been cut off with lower fluid pressure being supplied when the high pressure supply is cut off. While the lower pressure fluid may not actually drive the working member because of the momentum of the load, it must be supplied in such a manner as to provide a driving force to

the working member in the absence of the load. Thus, a simultaneous application of lower pressure fluid to opposed working chambers is not included under this definition.

SEE OR SEARCH THIS CLASS, SUBCLASS:

437+, for expansible chamber motors having a by-pass between opposed working chambers which is controlled independently of the inlet and exhaust control valve means. The by-pass in many instances is to prevent pressure or vacuum build up in a motor which is coasting.

441, for expansible chamber motors in which a valve is provided to permit ambient fluid to be drawn into a working chamber thereof as, for example, when the motor is coasting.

464, for double acting expansible chamber motors having means to simultaneously open opposed working chambers to either inlet or exhaust.