Surface · Rod Pump
Crank & Counterweights
The crank arms turned by the gear reducer, with heavy counterweights mounted on them.
What it does
The crank drives the pitman arms that rock the beam. The counterweights store energy on the downstroke and give it back on the upstroke, so the gearbox and motor see a smoother load.
Basics
| Counterweight location | On the crank or on the beam |
| Alternative | Air balanced units use compressed air instead of weights |
| Purpose | Reduce the load on the system |
Common failures
- Unit out of balance after well conditions change, raising gearbox load
Troubleshooting
- Symptom
- Unit speeds up and slows down within each stroke
- Likely cause
- Out of balance
- What to check
- Balance with both the power (motor) method and the mechanical (counterweight torque) method