Rotor loss has challenged rotary combines since their introduction. It occurs when insufficient threshed material passes through the concave early enough, causing excess crop to be carried into later rotor and separation regions. As those downstream regions become overloaded, grain may remain with the residue and be discharged from the rear of the combine. RPR Concaves™ use strategically arranged, progressively open concave-bar spacing to allow more crop material to separate and pass through the concave earlier, reducing the load carried downstream and helping reduce rotor loss while supporting combine capacity.

Round-bar concaves have been used in combines for decades. RPR Concaves™ incorporate a 90-degree milled, longitudinally notched round bar—known as the PacMan™ bar and disclosed in U.S. Patent No. 8,454,416. Used throughout the RPR system, the notch deliberately restricts crop flow to increase threshing engagement and promote effective grain-on-grain threshing. The notch is one element of the broader RPR design, which also includes the concave geometry, bar arrangement, progressively open spacing, and overall crop-flow configuration.

RPR Concaves™ use progressively open physical bar spacing to allow more crop material to pass through the concaves earlier. This reduces the amount of material carried into later rotor and separator regions, helps prevent downstream overload, and supports greater combine capacity. In CM Welding’s documented comparison with the applicable stock round-bar concave configuration, the RPR system allowed up to 68% more crop material to pass through the concaves. Actual results vary with crop, moisture, yield, machine configuration, settings, throughput, and operating conditions.
 

Since 2009, CM Welding has supplied Disrupters and Rotor Bars for John Deere and Case IH combines. In 2012, CM Welding introduced RPR Concaves™, a purpose-built threshing and separating system engineered to promote grain-on-grain threshing, improve grain quality, reduce downstream overload, and reduce rotor loss—helping farmers keep more of what they harvest. stes XPR 2 Concaves.

RPR Concaves™ use a 90-degree milled, longitudinally notched round bar—known as the "PacMan" bar and disclosed in U.S. Patent No. 8,454,416, to restrict crop flow and promote grain-on-grain threshing. The restricted-flow notch is designed to support efficient threshing, a cleaner grain sample, and reduced grain damage. RPR systems are manufactured in model-specific fitments for the listed combines and are designed to manage threshing, separation, and crop flow within each compatible machine configuration. Actual results vary with crop type, moisture, yield, machine configuration, throughput, operator settings, and operating conditions.

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