Bushing from the material processed into a number of sections, lining the outer cylinder inside. Pistons are made of seamless steel hollow cylinder, the outer surface with a smooth circular groove, the role is to allow access to the gap between the piston and bushing sand accumulation in the groove, to prevent sand and wear piston and bushing. The oil in the groove acts to lubricate the surface of the piston.
Check the pump when the pump to drain the oil in the tubing, can be salvaged suction valve, through the lower pole, so that the bottom of the piston snaps bite the suction valve salvage, the suction valve raised. However, this pump because the suction valve to capture the pump head space occupied, so that the pump anti-clearance and clearance volume, vulnerable to the impact of gas and reduce pump efficiency.
Most of the current into the tubular pump well, is installed in the lower part of the tubing oil spill, by opening the oil drain pipe to remove the oil. In the next big pump wells, because the piston diameter is greater than the tubing diameter, can not pass through the tubing into the piston, the method is first with the tubing down into the well, then into the sucker rod, the use of disengage device and pump Piston butt.
Tube pump structure is simple, low cost, in the same tubing diameter to allow the next into the pump diameter than the rod pump, and thus a large displacement. When checking the pump must be played from the tubing, workover workload, it is applicable to the depth of the pump is not, the higher the yield wells.
Rod-type pump, also known as the insertion pump, which fixed the top of the cylinder-type fixed-rod pump is characterized by both inside and outside the cylinder. The outer cylinder is provided with a vertebral seat and a retainer. Under the pump when the working tube with the tubing into the next well. And then fitted with a bushing, the piston of the inner cylinder connected to the lower end of the sucker rod into the outer cylinder and fixed by the retainer.
In addition there are fixed point at the bottom of the cylinder fixed cylinder bottom fixed rod pump, and the piston fixed to the bottom, driven by the sucker rod pump cylinder reciprocating motion bottom fixed rod pump.