Spindle pickers are complex, close-tolerance machines, requiring skilled training to operate. They also require precision shop equipment for repairs and adjustments, especially to the row units. Many producers rely on a dealer or specialty shop with trained service technicians for major repairs and adjustments. Pickers must be properly prepared to make sure they are capable of minimizing harvest losses.
Study and use the operator’s manual provided for your picker; it is the best source of information concerning adjustments. This reference gives insight into most common problems faced by picker operators, and it offers solutions to these problems. Preparation can begin with a thorough cleaning and inspection of all row units. Tighten or replace loose or missing or damaged fasteners.
Check and inflate tires to the pressure specified for that tire and picker load before making other adjustments. Low pressure in picker tires on one side can cause that side’s row unit height to be several inches lower. Low tire pressure can also promote a springing or bouncing effect of the row unit height control system. Low pressure eventually damages the tire. A damaged tire may burst and cause the picker operator to lose control during high-speed travel or cause a serious harvest delay during prime picking.
Row units of a cotton picker are tilted somewhat to cause the lowest spindles in the bars to enter the plants at the lowest possible height, maintaining the bottom of the row units about 1 inch above the soil. Proper tilt gives spindles a very slight vertical motion relative to the plant from entry to exit of the picking zone. Proper row unit tilt positions the front and rear spindles at slightly different heights within each plant. This arrangement leaves very little gap between spindles moving through the plants and provides greater harvesting efficiency. Tilt also provides relief at the rear of the cabinets to shed trash easier, thus reducing accumulation and dragging of shed leaves and plant debris. Faster clearing of debris reduces wear on the bottom of the cabinets.
Row units should attach to the toolbar with the front of the cabinet or front drum about 1-1.5 inches lower than the rear of the cabinet when positioned at picking height. Raising and operating row units higher may change the tilt slightly. Manufacturers (within the operator’s manual) typically specify a “pin-to-pin center” adjustment on the turnbuckle or adjustment link to obtain the specified tilt. Consider their specification a guide for average conditions – a starting point. Cotton fruiting very low, such as a crop planted “no-till” with little or no row bed, may retrieve much better with reduced tilt that puts the entire picking head closer to the ground. A greater amount of tilt may pick a higher percentage of larger plants with higher fruit set.
Picker spindles should be sharp at the front of the barb in order to grasp, hold, and pull seed cotton from the bur. Spindles tend to wear at the heights both where more cotton is picked and where more soil splashes onto the cotton before picking. Thus, wear occurs at different heights on the bars in different crop conditions. Usually, the bottom one-half to two-thirds of the spindles in a bar wear faster. Spindle wear can cause rust during picker storage, reducing aggressiveness and harvesting efficiency. Bushing wear is more rapid in the same height zones due to greater side force on spindles passing beneath the doffers.
Be sure that spindle assemblies are the correct left- or right-hand spindles to match both the nut thread and the drum where they are to be installed. The tips of the barbs should rotate into the cotton and point in the direction that the nut is turned when screwed into the bar. Immediately replace any broken or damaged spindles to prevent further damage to doffers, spindle moistening pads, and supports. Remove and identify the cause of any non-rotating or “dead” spindles – even if the bar needs removal and disassembly – to correct the problem.
A spindle assembly should have about 0.003- to.017-inch end play before insertion into the bar. Once it is in the bar, you should feel some slack between the drive gear in the bar and the spindle gear when rotating the spindle back and forth between your thumb and forefinger. If the spindle binds or has no slack between the gears, remove it, add shims, and retighten it until you can feel the slack. You can use a dial indicator to measure bushing wear when gauging the bar heights. Center the probe directly over the spindle between the dust collar and the start of taper on each spindle. Observe variations in the reading when forcing the spindle fully up to fully down vertically. Vertical movement in excess of 0.006 inch signals a need to replace the spindle bushings. Excess end play here may also be caused by wear of the thrust flange bushing on the base of the spindle nut.
Worn thrust flanges prevent spindle gears from meshing correctly with the drive gear; this problem accelerates the wear of the drive gear. Usually, spindle bushings are replaced when new spindles are installed. Several factors can shorten spindle life, such as weather, yield, crop and soil conditions, and the amount of leaf, sand, and trash in the cotton. However, spindle and bushing life should typically be approximately 600 hours of picking (fan hours).
A uniform picker bar height is critical in maintaining the correct gap between the spindles and the doffers and moistening system. A low bar may not doff cotton from the spindles well; a high bar may gouge or dig into the doffers and moistening pads. Certainly, check the bar height each year before the start of the harvest season. You should also take the following steps:
Note: Doffers should barely touch the spindles in the highest bar. If a feeler gauge is not available, a crisp dollar bill should slide with slight drag between the doffer lugs centered over the high point on the spindles.
Doffers remove the seed cotton from the spindles with an unwinding, wiping, and stripping motion toward the end of the spindle. The surface speed of the doffer is many times faster than the surface rotation of the spindle. Follow these tips to maintain the doffers:
Some row units are adjusted at the bottom of the doffer column to assure that the column is correctly positioned in relation to the bar. Follow your operator’s manual for alignment instructions. Inspect daily and ensure that all mounting hardware for doffer and moisture pad columns are tight. Routinely remove trash, dirt, and grease accumulation from the doffer column enclosure. Removing this buildup may prevent conveying chokes.
The purpose of the spindle moistening system is to constantly supply cleaning solution onto the spindles to remove plant gums and resins. This cleansing helps keep the spindles aggressive and easier to doff. The solution removes plant residue while seed cotton wipes the spindle, much like a dish cloth washing flatware. A cleaning solution mixed to the correct concentration is essential for proper function. Follow these recommendations to properly maintain and use the moistening system:
Picker row units clean, in addition to removing the seed cotton from the plant. The rotating spindle slings locks of seed cotton against the ribs as they leave the row, knocking burs and sticks off before cotton enters the doffer and air conveyor. Spindles work with the ribs to perform centrifugal cleaning much like a cotton gin. These tips will help you maintain the picker ribs:
Compressor doors should press the plant and open cotton bolls against the spindles. They should have the capability of moving away from and protecting the picking mechanism from damage by large plant volumes, large-diameter stalks, or chunks and rocks passing through each row unit. Doors are hinged and supported by adjustable springs. Rotating or tightening the shaft retaining the springs increases the pressure applied by the compressor door. Ribbed “scrapping” inserts are often fastened to the row side of the compressor door to promote a more aggressive contact with bolls toward the entry and plant exit. These steps will help you maintain compressor doors:
Cotton crop conditions are considerably different in more arid regions where crops are irrigated than in the rain-belt regions. Cotton plants grown in dry conditions tend to be short, wide, and “bushy” with the bulk of the yield concentrated in the lower 20 inches. Sometimes, passage of the large concentrated crop volume through row units causes field loss. General recommendations are to initially set pressure doors quite loose, and then tighten them as needed to improve picking efficiency. Do not use scrapping plates for front or rear drums if limbs are brittle as a result of a freeze.
Plant lifters must float with the contour of the soil surface, gently guiding the open bolls into the row unit. They need to operate within 1 inch of the surface without plowing soil or dragging leaves. These guidelines will help you maintain the lifters:
The best operating height for row units may be a compromise due to plant size, soil type, soil surface, shed leaves, plant debris, other obstacles, ground speed, and field terrain. Ideally, the bottom spindle on the front drum enters the row just below the bottom bolls. Where bolls have set 5-8 inches above the soil and cotton has grown on a relatively smooth row, this goal is easy to reach. Operating the row units at fairly high setting provides several benefits:
Lower boll set, rows with no or slight beds, or fields rutted by erosion or containing obstacles usually cause some yield sacrifices due to higher stalk and ground seed cotton losses. A lower picking unit reduces speed and the capacity of the picker, and it increases potential for damage and wear of the row units. For low-visibility night operations, choose fields or areas within fields where the cotton fruits higher and the likelihood of obstructions is lower. Simply raising row units as little as 1/2 inch can reduce dragging of shed leaves.
Constant raising and lowering of the row units (“hunting”) by the automatic height-sensing system will cause more seed cotton losses along the row and greater wear of the row unit mechanisms. Height-sensing shoes should be set for the average of the row units controlled by that sensor shoe at the chosen field speed of the picker. If a picker height sensor cycles – “begins to hunt” – as the picker moves along the rows, take these steps:
Inspect the tracks left by the sensing shoe to find out if a system is adjusted properly. A smooth, even track along the row indicates fairly constant height positioning. A heavy track followed by little or no track several yards down the row may suggest excessive cycling.
Reliable seed cotton conveyance from each picking unit is essential. Consistent seed cotton movement depends upon adequate air volume delivery by the fan to the cotton conveyor duct. All air ducts must be free of holes, duct connections must be tight, and the air system must be free of sharp edges where lint collects (roping) or debris accumulates. Follow these rules to maintain air conveyance systems:
Row unit spacing must match the planter spacing for the row pattern being picked. Attempting to pick row patterns that are not simple subsets of the planter will result in an odd row or rows that have varying spaces as you progress down the row. For example, if you try to pick cotton planted with a 10-row planter using a 6-row picker, there will always be one pass of the picker on well-spaced rows, followed by one or more passes on poorly spaced rows. This problem will result in much higher picker losses at places where the drills from two planter passes diverge.
Automatic row guidance provides more uniform row spacing between planter passes than a skilled, unaided operator can obtain at planting. Guidance systems with sensors to detect and correct the position of the row unit relative to the stalks in a row reduce operator fatigue and hold the picker on the row at faster picking speeds. They are capable of reducing field losses when the row units would otherwise vary off the row under manual control.
Poor plant stands in rows where the stand was damaged by standing water, weed infestations, inadequate moisture at planting, or other problems renders the guidance system less effective and may require temporary manual control. Set the guidance system sensors so the stalks enter the row unit halfway between the ribs and compressor door of the front drums.
Newer guidance systems have electronic adjustment from the cab. Setting the sensors on older guidance systems and checking the new systems require starting the picker down the row with the guidance system in operation and then stopping the picker with the hydrostat lever. After stopping, determine the positions of the ribs and spindles relative to the stalks being picked and adjust the unit to drive left or right as needed. You may need to repeat this procedure several times while making adjustments. However, once the system is set, it should not require additional adjustments unless the sensors become bent or damaged.