The unit API rates
API Spec 11E, published in its 2022 edition, covers the design and rating of beam pumping units, including every component between the carrier bar and the gear reducer input shaft. The standard exists because the unit is a machine with limits: run it past its rated load and the gearbox, the structural beams, or the rod string pays. A unit that is correctly sized but poorly maintained fails slower and just as expensively.
The points that fail
Field maintenance practice is consistent about where beam units fail. The gearbox oil level and condition is the classic killer: low oil, water, and debris destroy bearings and gears. V-belts need tension and alignment, the counterbalance setting drives peak loads, and the brake, stuffing box, and foundation bolts each have a check. Oil analysis and vibration monitoring catch wear while it is still a schedule item instead of a gearbox teardown.
The schedule and the record
A pumpjack program has three layers: the daily walk-around that catches leaks, noise, and belt damage, the periodic lubrication and adjustment pass, and the scheduled oil change and inspection. Standardized field checklists that log inspection points and operational parameters turn maintenance from memory into data, and that data is what separates a fleet of pumpers with a schedule from a fleet that fixes whatever breaks.
Pumpjack care belongs in the same maintenance ledger as equipment utilization, downtime cost, and MRO inventory. If the walk-around check is a mental note and the oil change date lives in a notebook, an operations audit will show which units are running on borrowed time.