(under the class definition) Apparatus in which the rotary expansible chamber device is provided with either (1) a trap or screen means to respectively collect or separate solid foreign material from the working fluid either in the working chamber or at the inlet or outlet thereto or (2) an enlargement of a working chamber part especially designed for allowing passage of solid foreign material laden working fluid through the working chamber of the device, the trap or screen means or the enlargement of the working chamber part enhancing the operation of the expansible chamber device.
(1) Note. Not included under part 2 of this definition are devices wherein there is included a seal, wear or other coating means forming part of the working chamber surface which may either be moved by or absorb the abrasive effect of the working fluid and any solid impurities therein. Nor are devices wherein the working member or the cylinder is made of nonmetallic material included here. However, such devices provided with an additional enlarged means especially designed for coping with solid foreign material in the
working fluid are deemed proper for classification here.
(2) Note. The removal of foreign particles from between substantially contacting relatively moving surfaces of the device by flushing with either pressurized fluid or mere leakage fluid is not considered proper for classification here. Such devices have been classified on other features.
(3) Note. A working fluid may include solid particles not considered to be foreign material (e.g., cement, wood pulp, etc.).
