Spring has sprung, but seasonal rains won't always be necessary to feed crops, thanks to the help of large programmable irrigation systems that let farmers program water output in patterns and direct chemical layout. This improves crop yield and quality, reduces waste, and eliminates an additional system.

Lindsay Mfg. Co., Lindsay, Neb., turned to Heidenhain Corp. to equip its Zimmatic irrigation system with a rotary encoder. The encoder lets the center pivot operate as part of a programmable controller system and lets the control panel read the pivot's position relative to a 360° circle. This is believed to be the first such design for an irrigation system.

Lindsay's Zimmatic center pivot point consists of ⅜-in. deep-galvanized angle steel legs and heavy duty cross members. An external collector ring eliminates water flow restriction.

The Heidenhain encoder mounts to the center pivot and is positioned to measure pivot movements, providing accuracy within one-third of a degree. The encoder is a Heidenhain absolute ROC 410 rotary encoder, so it remembers the pivot's location. This industrial-strength encoder series has its own bearings and is sealed to IP64 and IP67 for protection at shaft end and housing. The encoders are coupled by the rotor to the measured shaft through a separate coupling that compensates axial motion and misalignment between the encoder shaft and measured shaft.