10-point pivot maintenance plan

Center pivot systems don't get any respect. Farmers who fawn over their planters, tractors, or combines have a bad tendency to overlook pivots when it comes to preseason maintenance, which is a testimony to these machines' durability.

Still, some basic maintenance goes a long way to prevent a system from breaking down in the middle of the hottest day of the year. Component wear happens, too, resulting in less uniform water application as well as increased energy use, observes Bill Kranz of the University of Nebraska.

Keep pressure flow rate, use records

One of the best ways to identify worn components is to keep good records. Recording the outlet pressure, flow rate, hours of operation, and energy use each month provides an excellent means of evaluating pump and motor performance and identifying changes, Kranz says. But be sure the pivot is in the same position each time the operating pressure is recorded since the pump will produce different outlet pressures depending on whether it's facing uphill or downhill. And, systems without pressure regulators will have different flow rates. Compare the flow rate and pressure to the previous years' records.

Each irrigation system is equipped with a number of safety switches to shut the system down in case of failure. Run the system through a set of conditions that should cause each safety control to function.

A more difficult task is determining how efficiently the system is functioning. Periodic pumping plant evaluations will help identify whether the pumping plant is operating at an optimal level, Kranz explains.

The evaluation should identify the overall operating efficiency and provide the pump outlet pressure, system flow rate, and energy use rate. This information provides a base point to compare with future operating characteristics. If you have recent pumping plant evaluation results, simply compare the information you collect with the results to determine if the system is becoming less efficient over time.

Visually inspect the sprinkler in operation to identify if application is uniform and adequate or if repairs are needed. Kranz also offers the following checklist for preseason pivot inspection.

Preseason pivot inspection checklist

● Change the engine oil and filter.

● Replace the air and fuel filters.

● Grease driveshafts on pump and motor.

● Check spark plugs on gas, propane, or natural gas motors.

● Drain, flush, and refill the cooling system.

● Refill the drip oil reservoir and allow oil to drain into the drip line based on pump column length.

● Ensure that the right-angle gearhead is free moving and clean, and lubricate nonreverse pins.

● Run the motor at the normal operating speed for 45 minutes.

● Start the pump and walk along the system looking for malfunctioning sprinklers. Nozzle wear depends on the quality of the water and the system operating pressure. As a rule of thumb, sprinkler replacement should be considered after approximately 10,000 to 12,000 hours of operation. Be sure to replace malfunctioning nozzles with ones listed on the computer printout you received from the manufacturer.

● Check chemigation pump and safety equipment operation.