Sucker Rods
A pumping rod is a steel rod, usually 7 to 9 metres (25 to 30 feet) long and threaded at both ends, used in the oil industry to join the surface and bottom components of a reciprocating pump installed in an oil well. The pump cylinder is the visible surface drive of the well pump and is connected to the bottom pump at the bottom of the well by a series of interconnected sucker rods. Suction rods are also commonly available in fibreglass in lengths of 37 1/2 feet and diameters of 3/4, 7/8, 1 and 1 1/4 inches. They terminate in threaded metal ends, female at one end and male at the other.
Description
The surface unit transfers the energy required to pump the well from the drive motor to the pumping rod string. In doing so, it must convert the rotary motion of the prime mover into a reciprocating motion for the pumping rod. And it must reduce the motor speed to an appropriate pumping speed. The speed is reduced using a gear reducer, and the rotary motion of the crankshaft is converted into an oscillating motion using a walking beam. The crank arm is connected to the walking beam by means of a Pitman arm. The walking beam is supported by a Samson post and a saddle bearing. The horsehead and flange are used to ensure that the pull on the sucker rod cord is vertical at all times so that no rolling motion is applied to that part of the sucker rod cord above the stuffing box. The combination of polished stem and gland is used to maintain a good liquid seal to the surface.