Monday, November 3, 2014

Are There Advantages to Long Spans? | by John Kastl

Valley® offers the longest spans available from any pivot manufacturer; a 225’ 8000 series in North America, and a 72 m 8120 for international markets. Let’s take a look at these spans and how they can benefit you and your operation.

All spans consist of a pipeline to transfer and distribute water over the field, a trussing system to support the pipeline and a drive unit to move through the field. While all pivots have spans, there is no comparison between Valley span design and others. Our design philosophy has been developed over more than 60 years and is recognized as the industry leader by which everyone else is compared. We utilize the latest computer design technologies, such as 3-D modeling and finite element analysis, to ensure that our spans are the strongest with the longest life. The design quality is confirmed using both field testing and accelerated life testing.

Valley spans are more than just a combination of components. While others use modular designs to reduce manufacturing and inventory costs, we optimize the various components to provide the correct fit for each span length. This allows us to offer the longest spans in the industry while maintaining the same strength and durability you’ve come to expect from Valley.

Longer spans save you money by not only reducing the purchase cost of your machine, but also by eliminating the ongoing operation and maintenance associated with extra drive units. Fewer gearboxes, tower boxes, and tires mean fewer parts to maintain and repair. Fewer motors mean less energy required to operate your machine. And, one less wheel track in your field means less crop damage and more yield.

All Valley spans are designed for excellent stability. We use extra-deep trussing and special truss rods for each span to ensure a smooth shape and even loading throughout the span. The wide v-jack trussing stabilizes the pipe, and the Valley-exclusive tower support and tie brace design firmly anchor the span to the drive unit. Also, our engineers test each span length to ensure it meets our rigid specifications for stability and wind resistance.

One thing to keep in mind when selecting longer spans on fields with rolling terrain: small hills in-between the drive units are more likely to decrease crop clearance. In tall crops, such as corn, this can cause drag on the span. In those situations, the adjacent drive units should be high profile. On heavily rolling terrain, shorter spans are a better solution.

One concern we hear is that the higher weight of a long span results in deep wheel tracks and stuck machines. That’s not necessarily true. The key factor in wheel tracking is ground pressure, not span weight. Ground pressure is primarily related to tire inflation pressure, not the weight of the span. Selecting the proper tire size and maintaining the correct inflation pressure will ensure minimal wheel rutting even with long spans. For especially difficult conditions, Valley offers a number of tire and flotation options to ensure your irrigation machine can operate in nearly any field condition.






John Kastl
Product Manager - Equipment

John joined the Valley Irrigation Engineering Department in 2000 after having spent 11 years at General Electric Aircraft Engines. Today, he manages the equipment products for Valley (center pivots, corners, and gearboxes, to name a few), helping to develop the next generation of Valley Irrigation machines. John enjoys photography, home renovation, and travel. On his third birthday, John watched the first moon landing!

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