The Spindle-Type Cotton Harvester
The Spindle-Type Cotton Harvester
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.
Tire Condition and Pressure
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 Unit Tilt
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.
Tilt Adjustments
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.
Spindles and Spindle Bushings
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.
Spindle Adjustments
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.
Replacing Worn Parts
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).
Bar Height and Condition
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:
Thoroughly clean all row units, paying special attention to cleaning the base of each bar.
Raise or remove the doffers and moisture system columns to provide clearance and easy rotation of the drums.
Number each bar and its position in the drum with a permanent marker or steel stamp. Replace the bottom row of spindle nut assemblies in both drums with new or renewed spindle nut assemblies.
Position the dial indicator probe on the bottom plate of the row unit to strike the top of the bottom spindle of each bar between the dust collar and the start of taper on each spindle to indicate a depression of the dial probe for each bar.
Rotate the drum by hand, recording the bar position and the dial indicator reading (at the maximum point for the spindle) to the nearest 0.001 inch for each bar.
After you measure all bars, scan the readings for the bar with the greatest reading (highest bar).
Calculate the shim thickness (amount of shims) needed to bring each bar to the height of the highest bar.
Loosen the pivot pads for each low bar, add the proper amount of shims, and retighten.
Measure the bar heights again, and repeat the process until all bars are within 0.003- to 0.008- inch of each other.
Reinstall/adjust the doffer and moisture system columns to within 0.003-inch of the closest spindles.
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
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:
Doffer lugs should operate within about 0.003 inch from the spindle surface.
When crop conditions are very good, doffer-to-spindle clearances of as much as 0.020 inch may doff very well.
Do not lower a doffer column first before determining the cause of poor doffing. At times, this action only accelerates the wear of the doffers, spindles, and bushings without improving doffing appreciably.
The doffer material must be flexible enough to allow seed cotton, trash, and other material to pass between the lug and the spindle without damage. Weather, sunlight, and other factors may age and harden doffers.
Severely worn doffer lugs have reduced clearance for seed cotton to pass between the plate and the spindle. This problem can increase cracked seed, which is particularly important when cotton is harvested for planting seed.
Polyurethane (beige colored) doffers have reduced wear or “shavings” that are less prone to contaminate lint.
Doffer lugs with leading edges that become rounded from wear are less effective and should be reground or replaced with doffers with sharp leading edges. One cause of wear and rounding of the doffer lug leading edge is poorly shimmed bar height. It may also cause frequent spindle wrap and twist on low bars.
Replace doffer columns that have broken, torn, or rounded-edge doffer lugs with a properly ground doffer column. Adjust the height correctly.
See your operator’s manual for a recommended doffer adjustment procedure.
Here is one effective doffer height adjustment method: Power the row unit slowly using your tether. Lower the doffer column slowly while listening for a regular “thump, thump, thump” as the bars pass beneath the doffer column (use a stethoscope or a screwdriver from the doffer column bearing area to your ear). Then, slowly raise the adjustment until the thumping sound becomes faint to undetectable. This method also confirms that bar height is nearly correct when the thumps occur at regularly spaced intervals. Bar height needs to be serviced when the thumps you hear are random or at irregular intervals.
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.
Spindle Moistening System
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:
Clean any “gummy” or hardened residue from the bottom of the tank and flush the tank before the start of the picking season.
Clean the strainers and sediment bowl daily before picking.
Fill the tank to approximately 80% of capacity with clean water and add the proper amount of spindle cleaning solution to the tank (approximately 2 ounces per gallon of water or 1.6 gallons per 100 gallons of water). Finish filling the tank with water.
Bulk premixing of the spindle-cleaning solution decreases the time needed for filling the tank if you have a solution trailer.
Both picker manufacturers offer their own spindle-cleaning agents. Refer to your operator’s manual and the dealer for the best spindle cleaner for your crop conditions. A mild dishwashing detergent may do the same job once the correct solution ratio for your crop conditions is identified.
Operate the fan system powering the spindle moistening system pump. Check the pump pressure, remove the spray nozzle at the top of the moisture pad column, and see if the spray pattern is full and uniform. Remove the nozzle from its body, clean or replace the nozzle, and then check each moisture pad in both columns of each row unit to verify that sufficient solution is going to each spindle.
Adjust the moisture pad column so that the fins on the pads just touch the spindles as they pass beneath the pad.
During the day, routinely remove trash (especially cockleburs) and dirty seed cotton from the moisture pad zone. However, limited lint residue on the pads may help distribute cleaning solution to the spindles.
Picker Ribs
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:
Poorly spaced, damaged, or loose ribs may contact bars and/or spindles. This problem causes unusual wear and could potentially spark a fire in the row unit. The spindles, spindle nuts, and bars should not contact the ribs as they rotate.
Missing ribs will fail to clean burs, sticks, and leaf trash from the seed cotton as it is picked from the stalk.
Inspect the mountings and fasteners at the ends of the ribs for wear, and replace missing fasteners or damage as needed.
All ribs should be similar to a new rib. They should not be misshapen or have free movement within the mountings.