Valveless free plunger and system for well pumping

A rugged lightweight valveless plunger for free plunger well pumping comprising;

• (a) an elongated cylindrical aluminum body comprising:
• (i) a sealing section extending substantially the length of the body and formed by a plurality of circumferential grooves defining a plurality of annular aluminum sealing flanges;
• said grooves having the same width as the flanges and being closely spaced to increase the number thereof per unit of longitudinal length of the aluminum body, said grooves having curved inner surfaces each characterized by a radius equal to one-half the groove width;
• (ii) a fishing neck section having a smaller diameter than said annular sealing flanges;
• and
• (iii) a curved transition section of increasing diameter from said fishing neck section to said sealing section;
• (b) a pair of steel collars secured to said aluminum body on opposite longitudinal ends of said sealing section and having the same outer diameter as said annular sealing flanges;
• (c) one of said collars having a main section proximate said annular sealing flanges and also having a curved transition section of decreasing outer diameter to meet said curved transition section of said aluminum body in smooth profile;
• and
• (d) a steel neck cap secured to the end of said fishing neck section opposite said one collar and having a greater outer diameter than said fishing neck section;
• whereby the steel collars provide wear resistance and protection for the annular aluminum sealing flanges.