Rotary gear pumps

Claim 1

A ROTARY PUMP COMPRISING A HOUSING HAVING A RECESS OPENING AT A MACHINED AND SURFACE, A PAIR OF INTERALLY MESHING GEARS MOUNTED IN SAID RECESS AND FORMING THEREWITH AND WITH EACH OTHER INTAKE AND DELIVERY PUMPING COMPARTMENTS, THE END FACES OF SAID GEARS LYING FLUSH WITH SAID MACHINED END SURFACE, MEANS FOR DRIVING ONE OF SAID GERAS, A CASTING HAVING INLET AND OUTLET DUCTS AND ALSO HAVING A MACHINED SURFACE THROUGH WHICH SAID DUCTS OPEN, AND A COMPOUND PLATE STRUCTURE INTERPOSED BETWEEN SAID MACHINED SURFACES COMPLETING SAID PUMPING COMPARTMENTS AND HAVING INLET AND OUTLET PORTS REGISTERING WITH SAID DUCTS AND COMMUNICATING WITH SAID INLET AND DELIVERY PUMPING COMPARTMENTS, RESPECTIVELY, SAID COMPOUND PLATE STRUCTURE BEING MADE UP OF A PAIR SIMILARLY SHAPED RELATIVELY THIN SHEET MEMBERS HAVING A GASKET BETWEEN THEM EXTENDING OVER THEIR ENTIRE AREA, THE FACE OF ONE OF SAID SHEET MEMBERS BEARING AGAINST SAID MACHINED END SURFACE AND THE END FACES OF SAID GEARS, AND THE FACE OF THE OTHER SHEET MEMBER BEARING AGAINST THE MACHINED SURFACE OF SAID CASTING, AND MEANS FOR CLAMPING SAID HOUSING, PLATE STRUCTURE AND CASTING TOGETHER, WHEREBY A PLATE STRUCTURE OF ADEQUATE THICKNESS AND RIGIDITY MAY BE PRODUCED BY A DIE PUNCHING OPERATION.