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Boost Your Axial-Flow Output

Today we will look at Case IH rotary combines and discuss what owners and operators can do to improve combine performance, better maintain their machines and save money.

Case-IH ceased production of conventional combines in the mid to late 1970s and introduced a new single rotor “axial flow combine.” The first of the axial flow design was the fourteen series including the 1420, 1440, 1460 and 1480. Since the “14” series, we have seen the 16, 21, 23, 25 and now the 10 series rotaries, with models 7010 and 8010.

For the purpose of this article, I will focus on increasing flow through all Case-IH axial flow combines. Understand that the technology has changed significantly over the past 30 years, but the base concept and design share the same genetic code so to speak.

As mentioned in the previous article, what we are striving to achieve is maximum flow through the combine. This starts at the header.


For your pickup header, choose a high performance model — which would be a four-roller draper style or Rake-up pickup. Avoid older two-roller belt style pick-ups. Assure that belts and pickup teeth are in good condition.

For your straight-cut header, you want good auger flighting and you want proper adjustment of the auger as it relates to the stripper bar. The stripper bar is located on the back panel of the header directly behind the auger flighting. Over time, the flighting, stripper or both can become worn. Excessive tolerances can cause the crop to wrap around the auger instead of being fed horizontally into the feeder house. The table auger is adjustable forward and rearward, and the stripper bar can also be adjusted forward as wear occurs.

Full finger augers in heavy crop conditions are advantageous. It should be noted that straight-cut draper style headers generate very good flow. The crop enters the feeder house “head first” at all times from a draper header, which is optimal. Case-IH offers its own draper headers, or you could use a MacDon or Honey Bee header.


A worn or misadjusted feeder chain, damage to the feeder house floor, and worn sprockets can all limit flow through the feeder house. The rock trap could also inhibit flow if it is excessively worn. Inspect the beater vanes in the rock trap for bends or excessive wear.

If you are in stone free land and there is no risk of picking up rocks, the rock trap can be removed, which could slightly increase flow.


As the crop leaves the feeder house, it first enters the intake cone and rotor impeller. The intake cone is the same design in all combines and has directional vanes, which move the crop into the cone. It’s important that the vanes are in good condition.

From there, crop enters the threshing rotor. Case-IH has updated the design of its threshing rotor twice since it introduced the original standard axial-flow rotor. The first update was the specialty rotor and the latest design is called the AFX.

For the most part, the updated rotors fit the older combines so it goes without saying that the AFX rotor will provide the best threshing results and highest throughout. However, the condition of the

rotor is important regardless of what type you have.

On the standard and specialty rotors, make sure the elephant ears/intake impellers and impeller wear bars are in good condition. If you have four ears/impellers on the rotor, I would suggest going to a two-impeller set-up. It may seem counter intuitive, but rotors with two impellers feed faster and more evenly than the original four-blade set-up.

Also make sure your rub bars are in acceptable condition. If you have a standard rotor and need rub bars, I would suggest putting the rub bar money toward an updated specialty or AFX rotor. Rub bars and labour will run around $2,500 and a new rotor can be purchased for around $5,000 or less.


It is important to have concaves in good condition and the proper concaves for the crop being threshed. Wide wire concaves are becoming standard equipment as most farms grow seeds varying in size from mustard or canola (small) to peas and beans (large).

Changing concaves is not a five minute job. Using wide wire concaves and adding filler bars when required in small seed crops or in difficult threshing crops is easier and very effective.

The rotor cover/tunnel also has directional vanes bolted to it. These move crop residue in a spiral motion to the back of the combine. After 1,000-plus hours of threshing, the vanes can become worn down and should be inspected and replaced if warranted.


There is not much to go wrong with the rear discharge beater unless it has been damaged by a wad or foreign object. If it is undamaged and not worn through, no attention is required.

If your combine has a straw chopper, you want to make sure the knives and stationary cutter bar are in good condition. This helps reduce the power requirement of the chopper and improves straw spreading.


If you can get more horsepower from the engine you can increase combine capacity. The engine is no different than a human being. It needs healthy food (clean fuel and oil) and lots of clean air (good air filter and pre-cleaner).

You can go beyond clean fuel and air to obtain more power by adjusting the injection system or adding a power chip, but you must consider long-term sustainability of the engine when you take these steps. As with humans, we can “enhance” our personal performance but usually with longer term consequences.

I’ve tried to cover the basics, but have not gone into very specific details. If you have further questions, you can reach me at the phone number or email below.

Charlie Smith owns Combine World in Allan, Sask. For feedback on this article or questions about combines in general, you can contact him at 1-800-667-4515 or [email protected]

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