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How to scrutinize your combine to short-circuit breakdowns

Few people have witnessed the value of planned preventive maintenance more often than Successful Farming magazine’s Combine Doctor, Rodney Edgington. Years of field experience and a desire to maintain combines at peak operating performance have led Edgington to refine the process of detecting breakdowns before they occur.

Edgington taps into his considerable experience to create the following preseason inspection checklist for your combine. When following these basic examination pointers, have your combine owner’s manual in hand. 

“In that manual, you will find not only invaluable operating adjustment and daily maintenance tips but also a lot of preseason inspection pointers,” Edgington says.

The combine is a parts house full of such commodities as belts, sprockets, bearings, chains, and pulleys, Edgington observes. These key parts are crucial to making sure a combine operates smoothly or that power is delivered with full force. 

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Rodney Edgington has witnessed the wear and tear that harvest can inflict on the hundreds of harvesters he and his crew have inspected and repaired over the years. His company, Combine Specialties, services combines as well as tractors from across the High Plains out of the firm’s base in Ulysses, Kansas. Edgington’s firm also offers guidance inspections that provide customers with “step-by-step instructions on what we believe are the proper steps in getting you going on a preseason combine repair effort,” the former John Deere certified technician says.

Contact Edgington by calling 620/521-2223 or by visiting

belts, sprockets, bearings

When it comes to the myriad belts on a combine, the key is to examine the entire length of each belt, looking for cracks (a sure sign of old age and need for replacement), missing chunks, signs of separation, and glossy (or burned) sides. Discovering any of these problems calls for the belt to be replaced, of course. It can also indicate a problem with misadjustment (of an idler or tensioning pulley) or an impending parts failure (such as a bearing going bad).

Unlike typical V-belts, the belts powering the feederhouse or the rotor drive (on some combines) are of a special design and are engineered to transfer a lot of power. Much of the work they do requires power to be transferred strictly on the sides of the belts, so closely examine the belts for burned spots, grooves in their sides, missing pieces, and for separation.

Sprockets, another common component, reveal their age with wear on the drive side of their teeth. In this case, you should look for cupping, which affects the smooth operation of the chain. Chains tend to crawl on the sprocket, and hooked teeth won’t readily release rollers, Edgington explains. “Don’t replace a chain without replacing its sprocket. Leaving a worn sprocket behind greatly accelerates chain wear,” he warns.

Regarding bearings, the best practice is to remove drive belts or chains so you can spin the bearing by hand, listening “for rumbling when turning and feeling for rough operation,” Edgington explains. Although pulleys rarely present problems, you should take the time to examine them for wear, too. 

FEEDERHOUSE, drive system

The feederhouse is the most-often overlooked combine component when it comes to a preseason inspection. A well-maintained feederhouse is critical to provide a smooth delivery of crop to the threshing rotor. 

With the feederhouse, be sure to examine slats for wear or bending. It’s crucial that you also examine the feederhouse chains and their sprockets. Sagging chains accelerate wear, eventually leading to chains jumping on sprockets. 

“If you wear a new chain down to the end of its adjustment range, then take half a chain link out,” Edgington advises. “When the chain gets to the end of its full adjustment range a second time, then it’s time to replace it.”

The feederhouse floor is a high-wear item that needs scrutiny. Look for holes that may have been created by foreign objects. Also, check drum arm bearings for smooth operation. “All the elements that support that drum – bearings, bushings, and bolts – need to be looked at,” Edgington says.

Finally, look at the entire length of the drive belt for cracks, missing pieces, burned spots, and belt separation.

Completely disassemble and inspect the variable-speed drive pulley (sheave) assembly (if your combine is so equipped). “The pully is not easily taken apart but not something to be scared of, either,” he says. “Such an examination can reveal problems with the cams that can greatly affect the speed adjustment operation of the feederhouse and header reverser.” 

threshing elements

Your inspection of the threshing area needs to start with the induction (rotor) cone, checking to see if all of its hardware (vanes and weights) is intact and not bent or worn. “This is crucial, as missing components can lead to operating imbalance, which causes vibration,” Edgington explains. “Vanes are critical for providing smooth and even feed of crop into the thresher. You don’t want slugs of material hitting the thresher rotor since this can lead to underthreshing.”

Next, examine the leading edges of the rotor’s impellers for wear or for damage cracks. The rotor’s elements and rasp bars require scrutiny to detect excessive wear, missing hard surfacing, and damage to serrations. Chips on these components can increase grain damage, retard threshing, and boost threshing power requirements. 

Worn rotor rasp bars are a particular problem and are best measured with an indicator you can get from your dealership, Edgington advises. “I’ve seen smooth bars – even bars with holes in them – work. However, by using them, you are putting a load on the system. So measure the teeth on the bar to determine if they need to be replaced,” he says. 

Finally, remove the concaves to perform a thorough inspection. Look for rounded bars, missing wires, foreign objects, and residue buildup. Clean the concaves and reinstall them, making sure the units are level. Then check to see that the seals on covers are intact so they don’t leak crop during threshing. “Also, look at the frame on the entire rotor for structural cracks in both the threshing and separation areas,” Edgington recommends. “Look at the mountings for wear and for cracks, and make sure all fasteners are present and tightened down.” 

Separator area

There are three key components to examine in the separation area, which include the directional vanes, separation tines or bars, and the separator grates. 

Regarding the directional vanes, the key here is to look for wear and damage. “This is certainly the case when harvesting corn, as that grain can be very abrasive,” Edgington says. 

Next, look at each tine or bar examining these elements for wear. This is most often the case on the front or back row of tines or bars. 

“You can’t always tell if a tine or bar is worn and needs replacement just with a simple examination. That’s because they maintain their general shape as they wear,” Edgington explains. “Instead, you need to measure them.”

Be sure to take the time and check that mounting hardware is not broken or missing. Also, look over the separator’s grates for damage that might have been inflected by the combine ingesting a foreign object. 

“Such objects won’t punch through threshing concaves, but they will break a separator’s grates,” Edgington notes. “Lastly, look the grates over and check to see if they are bolted in securely.”

cleaning shoe area

As dirty as the job is, there is only one way to inspect the cleaning shoe area: Remove the chaffer and sieve, and crawl inside.

Begin the inspection by laying a piece of plywood on the cleaning shoe’s pan so when you crawl inside you won’t bend the sheet metal or break rivets or bend supports. 

“Examine the side rails for wear, the shaker arms and their bushings, and the rubber seals along the rails, which can pack full of debris and allow grain to pass through,” he recommends.

Also, inspect the cross augers, looking at their flighting for wear (if the flighting edges are sharp or rolled back) and to see if they have been bent. Check that the augers are not bowed, as this greatly diminishes their ability to move grain, which leads to shoe plugging. 

“Make sure the drives are set correctly to avoid wear on bevel gears. After crawling out of the cleaning shoe cavity and removing the plywood, survey the pan for rust, cracks, and holes (they retard grain flow).”

Inspect the chaffer and sieves for bent or broken elements, since either condition jeopardizes the smooth delivery of crop. Examine the elements’ shafts (rods) at the frame for elongated holes. Also, look over the deflector flaps as well as high-crop dividers for damage. “Pay particular attention to the chaffer or sieve frames looking for cracks and damage,” he says.

As far as wear is concerned, you will see that mostly in the center half of the chaffer or sieve, if it exists. Also, check assembly bolts for looseness, then tighten them to the torque specified in the owner’s manual.

Your inspection should include an examination of the cleaning fan. This entails scrutinizing the vanes for damage, which can happen when grain or foreign objects are ingested by the fan. 

Finish looking at the cleaning shoe area by examining the shaker arm assembly and the bushings. A bent arm or worn bushing can create vibration in the shoe, leading to damage of the chaffer and sieves.

elevator, augers

After finishing with the cleaning shoe, walk around and examine the grain elevator scanning for worn chains and paddles.

“Take the drive belt off the elevator and turn the chain by hand to examine the paddles, chains, and drive sprockets,” Edgington urges. “Paddles can be worn or rounded off at their top edges and, thus, would need to be replaced.”

Adjust the tension on the elevator so paddles don’t sag backward in operation. This is called backlegging (when grain cascades back down the elevator). This limits the capacity of the elevators and can cause the cleaning shoe to overload.

Regarding the clean grain auger, the key is to check for flighting wear particularly on the lower auger. “Where the auger converges into the elevator boot is an area of high flighting wear,” he says.

Also check the flighting on what is called the bubble-up auger in the grain tank while checking its bearings and drive box. 

Finish your inspection of grain conveyors by looking at the flighting on the unloading auger. Check the turret supports on the unloading auger for cracking as “this auger carries a huge amount of weight, which can lead to cracking at the elbow,” he says.

residue- management systems

The final stage of your combine inspection should include reviewing all key elements of the residue-management system – whether that system is a simple spreader or a more complicated residue chopper.

Begin this inspection by looking over the discharge beater that feeds the residue from the back of the rotor to the spreader or chopper. “Look for excessive wear, which can lead to a lot of operating vibration,” Edgington points out. “Examine all parts that come into contact with residue for wear and to see if they have been bent or damaged by foreign objects exiting the combine.” 

Regarding tailboard vanes and spreader elements, the key is to look for worn or damaged vanes since they compromise the distribution. Rotate traditional spreaders by hand to see that they operate smoothly (do not wobble) and check for wear on their distribution vanes.

When it comes to more complicated residue chopping systems, the key is to recon hinge points for stress cracks; these indicate excessive vibration or imbalanced operation. Balance is also key to chopper life. Missing knives or failure to replace knives in matched sets can set up vibration that could cause a chopper to damage itself.

Keep a sharp eye for worn knives as well – they do a poor job of sizing (chopping) residue. Worn knives can also cause chopper operation to drag, consuming more horsepower. If knives need to be replaced, do so in sets. Otherwise, the chopper is thrown out of balance. Finish the chopper inspection by scrutinizing the unit’s mounting hinge points for stress cracks and the rotor bearings for smooth operation. 

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