.~ Fluid serially moved to opposite side of pumping member {2}
556
.~.~ Control by movable rigid piston side wall
DEFINITION
Classification: 417/556
(under subclass 555.1) Apparatus in which the pumping member comprises a piston formed of plural relatively movable rigid side wall forming segments, said segments being movable to a first relative position during movement of the piston in one reciprocatory stroke direction to prevent fluid flow from one end of the piston to the other and movable to a second relative position during movement of the piston in the other reciprocatory stroke direction to permit such flow.
(1) Note. For classification under this definition, the relatively movable piston side wall segments must be fabricated of rigid material and be relatively movable in a manner to control fluid flow either between the segments and a cylinder side wall or between relatively engageable segment portions. The rigid segments may include resilient portions for sealing engagement with the cylinder side wall and such will not serve to exclude the device from classification under this definition provided that the relative movement of the segments themselves serve to control fluid flow rather than the mere flexing of a resilient piston portion responsive to relative movement of the segment.
SEE OR SEARCH THIS CLASS, SUBCLASS:
59, for a radially expansible piston for controlling fluid flow in a drilled well free piston-type pump.
489, for a single unitary piston forming element which is tilted relative to a cylinder in which it reciprocates for the purpose of controlling inlet or discharge of pump fluid.
SEE OR SEARCH CLASS
92, Expansible Chamber Devices, 247, for a pair of axially spaced relatively movable rigid piston forming members having a radially movable element
interposed therebetween wherein said radially movable element is either (1) flexible, or (2) has no disclosed valving function.
