To allow you to adjust precisely to the desired stroke, the length of the beam can be increased or decreased, which also changes the size of your stroke. To change the overall length of the beam, loosen the bolts shown in Diagram 7. Bolts 1 & 2 allow you to change the length of the beam between the fulcrum and the pump. Bolts 3 & 4 allow you to change the length of the beam between the fulcrum and the carriage. (Bolts 5 & 6 do not affect the stroke size and are only for weight adjustments, see Diagram 9.

When the length of the beam is changed, the distance of the carriage from the fulcrum is also adjusted to match the length of the beam.

When adjusting the beam and carriage, the pitman arm must be vertical to the ground when the crank arm is at the 12 o'clock position (see Diagram 6). The crank arm should then be rotated to confirm the stroke is within tolerances of the displacement pump.

You therefore have two methods by which to increase or decrease the size of your stroke -  increasing or decreasing the length of the beam or increasing or decreasing the length of the crank arm. These features allow you to adjust your stroke exactly to the required size.

NOTE: On new wells it is recommended that a smaller, rather than a larger, diameter displacement pump be used to achieve BPD requirements. This reduces the load factors on all facets of the equipment and motor.