Texas Rubber & Specialty Corp. v. D. & M. MACHINE WORKS, 7707.

• Citation: 81 F.2d 206
• Decision Date: 26 February 1936
• Docket Number: No. 7707.,7707.
• Parties: TEXAS RUBBER & SPECIALTY CORPORATION et al. v. D. & M. MACHINE WORKS et al.
• Court: United States Courts of Appeals. United States Court of Appeals (5th Circuit)

81 F.2d 206 (1936)

TEXAS RUBBER & SPECIALTY CORPORATION et al. v. D. & M. MACHINE WORKS et al.

No. 7707.

Circuit Court of Appeals, Fifth Circuit.

January 22, 1936.

Rehearing Denied February 26, 1936.

Jesse R. Stone and Lester B. Clark, both of Houston, Texas., for appellants.

J. Vincent Martin and E. A. Berry, both of Houston, Tex., for appellees.

Before FOSTER and SIBLEY, Circuit Judges, and DAWKINS, District Judge.

SIBLEY, Circuit Judge.

A decree was rendered upholding patent No. 1,718,474 issued June 25, 1929, to John W. McQuaid, for a piston for slush pumps, adjudging infringement by a similar piston made and sold by Texas Rubber & Specialty Company and H. W. Millmine, and awarding injunction and a reference to take an account. This appeal contests the validity of the patent and denies infringement.

During the past two decades oil wells have been drilled to depths sometimes exceeding two miles by the use of hollow drill stems through which very soft mud called "slush" is continuously pumped, passing out below the drill head or auger and carrying the materials cut by the drill head up around the outside of the drill stem to the surface, where the coarser particles are taken out by sedimentation and the slush is used again. Pressures on the pumps of several hundred pounds to the square inch are reached. The slush carries considerable abrasive material which tends to cut out the liners of the pump and destroy the packing of the piston. The present patent presents a piston of rubber molded over a rigid (metal) skeleton composed of a central core or hub, through which the piston rod passes and to which it is secured by nuts, with a flange extending radially from the core nearly to the walls of the pump liner, there being rings and grooves on core and flange into which the rubber is formed and vulcanized to securely hold it. The rubber at the working end of the piston is built up into a ring which protrudes beyond the face of the piston and is made a little larger than the bore of the liner so as to press tightly against it, the rubber behind the ring fitting more loosely. The pistons are usually for double acting pumps so that there is such a protruding ring on each end, the portion of the piston between the two rings being out of contact with the liner. The body of the piston is hard rubber, but the protruding rings are more pliable, so that the liquid in front of the piston in its work stroke presses the ring firmly against the liner, preventing leakage and especially preventing abrasive particles from getting between the piston and the liner to the destruction of both. The rings are not feather-edged, but have an ogee section giving them a greater stiffness and stability. The metal pistons and packing rings which are used in steam and internal combustion engines and in some pumps for smooth liquids were quickly ground away in slush pumps. Rubber was known to be lubricated by water and to withstand abrasion and to make a good seal with a metal pump liner and had long been used in pumps for low pressures. It was also in use in slush pumps for high pressures, but in the form of a mass included between two metal plates which could be squeezed together to force the rubber into close contact with the liner. Such pistons were strong and did the work, but the rubber would wear faster at both ends than at the center of the piston and abrasive matter would collect between the worn portions and the liner or around the confining plates and score the liner so that the slush would soon begin to leak past the piston under the heavy pressure, acting like a sand blast in cutting out the working parts. The McQuaid patent is designed to secure a more perfect prevention of abrasion while retaining a strength equal to the heavy work required.

There are thirty-four claims, all for similar combinations of elements. No particular claims have been singled out as infringed. Claim 14 may be quoted as typical: "A piston comprising a relatively rigid axial core; a relatively rigid radial flange on the core intermediate its ends; the lateral faces of the flange and the periphery of the core being recessed; a rubber packing member molded on the core, encasing the flange and extending into said recesses; said packing member having a substantially concave periphery and longitudinally overhanging peripheral ends, the end faces having an ogee curvature adjacent said overhanging peripheral ends." No complete anticipation is shown, but we find every one of the elements of the claim in the prior pumping art. The use of rubber as a packing material, especially in the presence of abrasives, was old. The expanding ring held by pressure against the liner, both in the feather-edge form for slight pressures and ogee form for heavier pressures, was old. The support of the rubber packer by metal was usual and the molding of the rubber over the metal was no novelty. Recesses on the metal to hold the rubber better had been long practiced. Making the protruding rings oversize to keep them in contact with the liner is probably an old practice, though mentioned in no cited patent. Mechanical skill would suggest...