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Combine Maintenance

There’s nothing more important to us than keeping you up and running, especially during critical harvest times. The harvest season puts huge demands on your equipment and unexpected breakdowns or poor performance cost money. With the season ahead, now is the time to give your harvester a full service so it’s ready to go at a moment’s notice. To harvest to your crop’s full potential you need the support of the John Deere dealership network committed to keeping your harvester operating at its full potential.

This section provides information on commonly replaced wear parts for combine harvesters. Guidelines are given on how to determine when these parts are worn and should be replaced.

The importance of replacing worn components on a combine harvester cannot be overemphasised. Worn components result in poor combine performance, reducing profits. For example, up to 80 percent of crop loss can occur at the platform or header area of the combine. Whether you’re harvesting wheat, barley, rice, soybeans, corn, grain-sorghum, or other crops, proper cutterbar or gatherer unit maintenance and regular replacement of worn parts will reduce loss and increase profits.

Feeding, threshing, and separating performance is reduced if maintenance and replacement of worn parts are not done at the proper time. Poor feeding of material to the threshing area can cause plugging, which can result in cylinder drive component failure or incomplete threshing. Worn threshing components cause incomplete threshing or grain damage when cylinder speed is increased to compensate for worn components.

Worn material-handling components, such as augers and elevator paddles, can result in reduced combine productivity.
Contact your local John Deere dealer for more information or visit JDParts.JohnDeere.com.

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Starting with the platform, the parts that experience high wear are the cutting components -- knives, guards, wear plates, and hold-down clips. The knife is a series of shears. To cut effectively, the knife must run smoothly in the cutterbar, and every knife section must rest on the guard, in position to make a shear cut. The knife guard, wear plates, and hold-down clips must be in good condition and set correctly.

Dura-Cut™ Knife Section
The John Deere Dura-Cut™ knife section is a product of the latest in state-of-the art manufacturing. This section provides the highest level of quality and cutting performance. Dura-Cut™ serrated sections have deep serrations, so they stay sharper and wear longer. The serrations are 40 percent deeper on the Dura-Cut™ section than on the section they replace, and from 23 to 60 percent deeper than the competitors’ sections.

Dura-Cut™ sections are made from high-carbon steel for toughness and longer life. Tests show several competitive sections fail to meet John Deere specifications. Sections with too-high carbon content (brittle sections) or too-low carbon content (soft sections) can reduce section life. Dura-Cut™ quality means tough construction, uniform thickness, and long life.

Dura-Cut™sections are heat-treated twice and checked automatically to ensure specifications are met. This rigorous testing ensures Dura-Cut™ quality.

An automated hard-chroming process gives the section a more consistent and controllable chrome application, which results in stronger teeth and longer section life. This process eliminates the cracking or peeling common with competitive sections, which have been soft-chromed.

Dura-Lite™ Knife Section
The Dura-Lite™ knife section has the same strength and cutting performance as the popular Dura-Cut™ knife section. The reduced weight of the Dura-Lite™ section lowers the mass of the cutterbar, reducing power requirements and lowering vibration for a smoother-running knife, and less stress on the knifehead and drive system.

Coarse-Tooth Sections
If you want a more aggressive sickle section for coarser, dryer crops, coarse-tooth Dura-Cut™ or Dura-Lite™ sections are available. The coarse-tooth section has seven serrations per inch. It grabs the stalk and brings it to the ledger surface while maintaining a well-defined, self-sharpening pattern.

Double-Cut Knife Section
The double-cut knife system, used on the 900D Series Draper Platforms, provides customers with faster, cleaner, and smoother cutting action for small-grain harvesting. The system uses the unique Dura-Twin™ knife section, with a full four inches of knife travel. This knife section provides a cleaner cut versus the tearing effect of shorter-stroke cutting systems. The Dura-Twin™ sections are manufactured to the same quality specifications as the Dura-Lite™ and Dura-Cut™ knife sections to ensure long wear life and high performance.

End Sections
End sections reduce troublesome cutterbar clogging in thick and badly tangled crops.

 Knife Guards
Knife guards are designed to provide long life and top productivity. The guards are forged from low-carbon steel to ensure durability. The forging process gives the guard a smooth surface for snag-free crop flow to the knife. A special heat-treating process provides extra hardness so the guard retains its shock-resistant characteristics.

The upper lip of the guard is wider than the cutting surface. This lip keeps the cutting edge sharp longer by protecting it from damage by foreign material. The lower portion of the guard is designed in a "V" shape and flares out into the wide cutting surface of the guard, positioning the crop stem at a slight angle. The result is a clean, scissors-like cut.

Dura-Guard™ Knife Guard
The Dura-Guard™ Knife Guard is standard equipment on all newer 900 Series Platforms and is also available for all older 200 and 900 Series Platforms.

The guard has a high tensile strength because of the higher carbon and chrome content in the steel, plus the increased core hardness. A secondary hardening process toughens the ledger surface, giving a hard, wear-resistant cutting surface. The result is a guard that stands up to hard, rocky, cutting conditions.

Double-Cut Knife Guards
The double-cut knife system is standard equipment on all 900D Series Draper Platforms and features a four-inch knife stroke for smooth cutting action. The double-cut system uses a unique set of knife guards that work with the Dura-Twin knife sections. The guards are available in "long-short-long" or "short-long-short" versions for the different cutterbar lengths.

The double-cut guards have the same durability and reliability characteristics as the other John Deere guards.

Wear Plates
Wear plates keep the knife aligned with the ledger surface to ensure a clean shearing action. Worn plates cause the knife to chew and tear the crop.

John Deere wear plates are heat-treated for long wear life. Sharp, forged ends assure even sickle bar contact, and rectangular attaching holes provide positive alignment. Uniform and consistent manufacturing processes ensure a tight, perfect fit.

Hold-Down Clips
Hold-down clips must be durable to prevent the clip from breaking under stress. The hold-down clip keeps the knife section in the shearing position. The ideal cutting position is when the bottom surface of the knife section is kept in contact with the lower self-sharpening edge of the rock guard groove, creating a scissors-like action. The hold-down clip flexes under field stress conditions, but is strong enough to hold the knife section in place.

Auger Fingers
As the material moves to the center of the platform, auger fingers, finger bearings, and finger guides deliver material to the feeder house. The fingers and bearings should be checked periodically and replaced if there is excessive play.

The John Deere auger fingers are made of boron steel. The surface is heat-treated for long wear. A narrow, breakaway groove in the finger protects it and allows the finger to break, rather than bend, at a precise point if it hits a rock or other obstruction. This prevents severe damage to the auger.

Corn Heads

As the combine moves through the field, the gatherer points are positioned between the cornrows. The stalk rolls pull the cornstalks down so the deck plates will snap off the ears. Trash knives prevent weeds and trash from wrapping around the stalk rolls. The gatherer chains move the ears up to the auger. The auger moves the ears to the front of the feeder house where rubber paddles feed the ears into the feeder house.

It costs time and money if the gatherer row components are worn or not properly maintained. Worn gatherer row components may result in:

  • Stalk roll wrapping
  • Row unit plugging
  • Feeder house plugging
  • Ear loss
  • Pulling up of cornstalks
  • Kernel damage
Two critical parts that affect productivity on a corn head are the stalk rolls and gatherer chains.

Row-Crop Heads

As the row-crop head gatherer points are positioned between the rows, the points lift and guide the crop into the gatherer belts. The gatherer belts extend forward of the rotary knife to grip each stalk before it is cut. Each row unit has its own rotary knife, equipped with six high-carbon cutting sections. After the rotary knives have cut the stalks, the gatherer belts convey the stalks to the auger. The auger delivers the stalks to the feeder house. A trough, located under the gatherer belts, reduces crop loss due to shatter.

When row unit parts are worn or not properly maintained, the following problems may occur:

  • Knife wrapping
  • Row unit plugging
  • High losses
  • Crop stripping
  • Grain damage
Three critical parts that affect productivity are the rotary knives, stationary knives, and gatherer belts.

Rotary and Stationary Knives

Sharp rotary knives are important for maximum row-crop head harvesting efficiency. The knives are manufactured of long wearing, high-quality steel. The edges of the knife are beveled and coated with a metal alloy for increased edge life. To ensure clean, smooth cutting, replace rotary knife sections and stationary knives when they are dull.

Bolt-on knife sections are easy and convenient to replace. No modification is necessary to replace riveted knife sections with bolt-on knife sections. Special plow bolts and locknuts are required.

Gatherer Belts
The gatherer belt gathers and conveys the crop to the cross auger. As the two-ply belt wears, it will become frayed or torn and should be replaced.

Feeder House Conveyor Chain

The feeder house conveyor chain delivers crop material from the front end of the combine to the threshing area. A worn conveyor chain will not move material efficiently, causing a material flow problem. The results of a worn feeder house conveyor chain are:

  • Feeder house plugging
  • Chain jumping sprocket teeth
  • Slug feeding Reduced ground speed
  • Higher losses
  • Premature threshing
  • Grain damage
Tension is the major cause of feeder house conveyor chain wear. It is normal for center strands to sag more because of the weight of the slat and the upward force of crop material. Shaft and bearing failures are also often caused by excessive chain tension.

Feeder house conveyor chain, with wide-spaced slats, is standard equipment for all 9000 Series Combines. The under-slot slat and chain conveyor system smoothly delivers material to the threshing area. Conveyor chain, with narrow-spaced slats, prevents corn, grain sorghum, or sunflower stalks from "hair-pinning", wrapping over the slats, wrapping on the drive shaft, or causing the chain to jump teeth on the drive sprockets.

The narrow-slat feeder house conveyor chain was standard equipment on all Titan Combines (PIN 60000 and up). The wide-spaced-slat feeder house conveyor chain is available as a service part only. It provides better material handling in crops such as small grain with short straw, and green material that can stick to the feeder house bottom.

Feed Accelerator
Single Tine Separator (STS) Combines incorporate a feed accelerator to move the crop material from the feeder house into the feed section of the STS module. The feed accelerator features a 10-wing design with three replaceable wear strips on each wing. The wear strips can be reversed once to extend the life of the strips.

Failure to reverse or replace worn feed accelerator strips can affect the combine's material handling performance, especially in tough, green-stemmed crops.

Rasp Bars

The rasp bar cylinder, with open bar concave, receives crop material from the feeder house for threshing, and separates up to 90 percent of the grain from the straw.

When the concave and rasp bars are worn, productivity can be affected in several ways:

  • Incomplete threshing
  • Grain damage resulting from excessive cylinder speed
  • Reduced combine capacity
  • Poor feeding
  • Excessive power requirements
  • Poor grain tank sample
  • Cylinder and concave plugging
  • Separator grain loss
Smooth Rasp Bars
The surface of the smooth rasp bar has no serrations. The smooth surface helps to deliver a "softer", less aggressive threshing impact than a regular rasp bar. This bar is recommended for use only in food corn.

Hardened and Non-Chromed Rasp Bars
This serrated rasp bar has a gently contoured surface design that wears to an even, smooth profile after only 50 to 100 hours of use.

This rasp bar is recommended for use in harvesting corn, popcorn, soybeans, malting barley, edible beans, or any seed crop where high quality grain is demanded.

Hardened and Chromed Rasp Bars
The chrome, overlay of this rasp bar provides twice the wear life of the non-chromed rasp bar. The chromed rasp bar also features a smooth, contoured profile design, but new, sharp surface edges won’t "wear off" as rapidly as on the non-chromed rasp bar.

As a result, this rasp bar is not recommended for use in high-moisture corn or soybeans, or any crop where the highest quality grain is the main consideration. However, this rasp bar is ideally suited for general use in all crops where long-lasting, efficient threshing performance is the primary concern.

STS Threshing Element
In place of the rasp elements used in cylinder/straw walker combines, the STS combines feature a unique, smooth, threshing element. This patented, uniquely shaped element is manufactured of an extremely tough, very hard material called austempered carbidic iron. The smooth threshing surface of the element helps to maintain optimum grain quality in all crops,
while the trailing, blade-like edge moves the crop material rearward through the STS module.

To maintain overall combine performance, the STS threshing elements should be replaced when the height of the rear blade edge is worn to approximately 1/2-inch. Replacement elements are sold in weight-matched sets of three so that proper threshing module balance is maintained.


Concave wear can be detected three ways:

  • Rounding of the concave bar
  • Wear of concave bar height
  • Wear in the centre portion of the concave
As the concave bar becomes rounded from its original square edge, aggressive threshing is reduced, particularly in small grains. The height of the concave bar can be reduced by ¼ inch before the concave rods will be exposed. The concave can be checked for wear by placing a straight edge across the concave and determining the difference in the high and low points.

If the difference is more than 1/8 inch, the concave should be replaced for maximum performance. This guideline is especially critical when harvesting small grains. Material fed to the threshing system should be uniformly spread over the full width of the machine, to prevent the center section of the concave from having more wear.

Concave Inserts
The concave inserts are standard equipment for corn combines, and give the Walker and 50 Series Combines more versatility in different crop conditions, to deliver top threshing and separating performance.

Concave inserts may be required when harvesting high moisture (above 20 percent) or hard-to-thresh corn. They can also be used with the spike-tooth concave.

The concave inserts prevent cobs, with un-threshed kernels, from passing through the open area at the rear of the short wire concave, to ensure complete threshing.

Cylinder filler plates are also recommended when harvesting corn.

STS Concave
The Single Tine Separator combine can be equipped with any one of three different types of concaves to best meet crop variety and conditions.

As concaves wear, aggressive threshing action is reduced, particularly in small grains.
Small-grain and large-wire concaves can be checked for wear by placing a straight edge along the concave bar (front to rear) and determining the difference in the high and low points. If the difference is more than 3/16-in. (4.5 mm), the concave should be replaced.

The round-bar concaves can be checked by measuring the thickness of the bars. If the thickness of the bars is less than 7/16-in. (11 mm), the concave should be replaced.

Maximiser Concave
Strict manufacturing processes maintain the correct radius of the concave within a tolerance of 5/64-in. This radius and tolerance is established in relation to the concave bars and not the sidebars.

The design of the concave sidebars matches the radius of the curvature of the top surface of the concave crossbars. This provides better and easier gauging of the concave-to-cylinder clearance, by eliminating the possibility of the concave bars being below the sidebars.

For conditions where threshing is very difficult, concave filler strips can be added to enhance threshing. When installing strips, use as few as possible to avoid reducing the separating  efficiency of the concave to the point of overloading the straw walker with free grain that will lead to increased crop loss.

New rasp bars and/or concave will provide:

  • Complete threshing
  • Aggressive feeding
  • Maximum combine capacity
  • Smooth feeding
  • Minimal separating losses
  • Less power required
  • Excellent grain sample
  • Reduced cylinder and concave plugging
  • Reduced cylinder speed

Material Handling

The elevator chains, paddles, and augers of the material handling systems constantly convey material, resulting in wear. The chains should be checked for stretch, and adjusted or replaced as required.

The rubber paddles can develop rounded corners and edges, resulting in grain leakage. As the auger flight wears, a razor edge will develop on the flight and result in a smaller-diameter auger. Worn material handling components result in:

  • Reduced system capacity
  • Plugging Reduced harvesting capacity
  • Reduced ground speed
  • Grain damage
  • Increased power requirements
The most common reason for excessive elevator chain wear is too much tension. A chain that has too much tension will get tighter as the chain conveys material and could cause shaft and bearing failures.