PRODUCTS Driving Center Pivot Irrigation

Since 1978, UMC has been working to continually deliver stronger, better components to keep your center pivot irrigation system running longer and more efficiently. To truly maximize the service life of your gearbox, a little time spent on basic maintenance can go a long way.

UMC Founder Bill Smith’s Basic Maintenance Tips

Today’s driveline components are the result of many years of research, testing and in-field operation. The development has led to an increase in sophistication and durability of gearboxes and related components. As evidence of this, pivot manufacturers now routinely offer exceptional gear drive warranties, typically extending seven to eight years. However, most of those warranties are valid only if owners adhere to strict maintenance and service requirements. Warranties withstanding, irrigation professionals would be wise to take good care of their drive line components, thereby extending use life and increasing cost efficiency.

Product Maintenance

Maintenance Document – EnglishSpanishChinese


Following are three gearbox maintenance fundamentals:

  1. Upon initial installation of a gearbox, it is important to check rear mount bolts and lug nuts. These bolts should be checked routinely throughout the gearbox service life to ensure they adhere to manufacturer specifications.
  2. Upon setup and installation, and before running the system initially, each gearbox should have the top fill plug removed. This “burping” of the gearbox will normalize pressure in the gearbox. Altitude above sea level and temperature can pressurize your gearboxes. At the same time, oil level can be verified.
  3. Your center drive, be it a worm gear or spur gear, should be routinely checked for proper oil level.

Most manufacturers recommend servicing gearboxes during downtime between crop cycles, with specific tasks designated before and after each crop cycle. With more hours of annual operation or with higher operating temperature or with faster running speeds, the more frequent the servicing.

Before A Crop Cycle

  1. Check oil level and make sure it is filled to manufacturer specifications.
  2. Rock the wheel and observe to be sure there is no play in the input shaft. If the shaft is loose, remove the end cap, install a pre-load shim to remove any excessive play between bearing and race, and tighten the end cap to pre-load bearings. This would also be a good time to replace any leaky seals.
  3. Make sure end cap drain holes (if your boxes have them) are free and clear of mud, silt and other debris. For example, mud dauber wasps like to fill these holds. If debris is found, it can be cleared using a small nail. While cleaning out the debris, take care to avoid damaging the inside seal.
  4. If your wheel box has a diaphragm expansion chamber, check for oil seepage. A broken diaphragm will allow oil to discharge when the gearbox is pressurized. Make sure the cover vent is clear allowing for diaphragm expansion.
  5. Check all areas around the end caps for oil leakage, and tighten all fasteners as needed.

After a Crop Cycle

  1. Check for seal leakage on input and output. Replace if necessary.
  2. Remove the top plug after observing for evidence of oil leakage.
  3. Remove the bottom plug and properly drain all oil and water. Wheel boxes make a grey “mayonnaise” mixture of oil and water, none of which should remain in the gearbox. On all new installations, all oil must be drained after the first year of operation, per warranty instructions.
  4. All oil used should be per the manufacturer’s recommendations. Some operators are using “0” weight, moly-type grease in lieu of EP gear oil. Remember that grease is essentially oil and soap. When the oil is used to the point of degradation, just the soap remains, providing much less lubrication and compromising the gearbox components.

Following these basic maintenance guidelines, as well as those stipulated in your irrigation systems manual, can go a long way to ensuring proper, long-term operation of your driveline components. Though they require effort, these maintenance steps will be more than worthwhile in the long run, and shouldn’t be overlooked.