Tuning up your mower-conditioner

Paul Craig, Senior Extension Educator, Penn State University

Agricultural engineers note that disk mower knives must be regularly checked for dullness and wear. Disk mowers will cut even when knives are extremely dull, resulting in a “ragged” cut. Agronomists point out that this raggedness often leads to plant health problems later in the production cycle. Take time now to check your mower knives.

On the outer layer of plant leaves and stems is a “waxy” layer that prevents internal plant moisture from being lost from the plant during the growing process. The plant has stomata on the leaf surface that regulate this process when the plant is growing. Upon harvest, this “waxy” layer works to limit the rapid drydown of the crop. Mowers have incorporated conditioning systems to crack, split or scratch this layer.

One type of conditioning system uses intermeshing rolls to bend and crush plant stems. With all machines, the proper set-up of these rolls is critical for optimum performance. The gap or clearance between intermeshing rolls is important. Too great of a clearance and the stems pass through without any crushing. Too small and leaves will be removed, in addition to excessive roller wear and plugging.

Roll clearance for effective alfalfa conditioning needs to be set and maintained at 0.060 (1/16) to 0.090 (1/32) inches to achieve effective conditioning. Check your operating manual for additional references and the procedure to make this adjustment.

The following procedure can be used to measure your roll clearance gap. First, ensure safety by shutting off your tractor engine and disconnecting the PTO. Next, lower the cutting platform to ensure the rolls are at operating conditions.

Procedure:

1. Cut three pieces of aluminum foil 18 inches in length.

2. Form three separate rolls by wrapping a foil strip around a rod or dowel that is 3/8th-inch in diameter. Then slide the roll off the rod taking care not to crush the foil roll.

3. Place one foil roll in the center and the two other rolls about 1 foot from each end of the conditioning rolls. Place the foil rolls perpendicular to the roll.

4. Make sure cutting platform is lowered, and turn the conditioning rolls over by hand until the foil rolls come completely through.

5. The rolls will crush the foil and minimum roll clearance can be determined with a caliper. Take several measurements along each foil roll and determine an average. Take the measurement where the smallest clearance occurs. HG

References omitted but are available upon request at editor@progressivedairy.com

—From Penn State Field Crop News, Vol. 7, No. 7