Snow Part 03: Ejective Precleaners – Stratification of Debris Fields

Through patented design and processes, the Series 9000 is able to stratify the snow within the precleaner, allowing it to optimize the FULL LENGTH of the ejection slot for ejection of snow.  This allows the Series 9000 to process large amounts of snow without clogging or bogging down.  No other precleaner does this!

All atmospheric ejective precleaners create restriction in the intake system because they have a rotor that spins, taking energy from the high volume of air which is pulled through the intake system during engine operation. The rotor impacts the debris in the air stream, driving it to the outer wall of the precleaner where it is ejected from the precleaner through a slot or port in the wall.

With the exception of the Series 9000, all atmospheric ejective precleaners have a crude rotor which impacts the debris much like a cricket bat hitting a dirt clod, smashing it into fine particles and exploding it into the air stream. This process homogenizes the debris instead of stratifying it, so the debris is circulating inside the precleaner in a single band. Even though the precleaner may have a long ejection slot, only a portion of the slot is actually used.

The Series 9000 is unique because it effectively stratifies the debris field into multiple bands by design. There are three strakes (angled fins) that are evenly spaced out along the inner wall of the dome. <more on how it works>
<< Clear demo unit shows Series 9000
louvers and strakes which stratify debris into bands.

  1. When the debris enters the precleaner through angled louvers, some of the debris is immediately caught in the lowest strake, closest to the prescreen.
  2. The debris which gets past this first strake is driven by both centrifugal force and by impacting with the curved rotor arm back into the wall of the dome where it is caught by the second strake.
  3. The particles that get by the 1st and 2nd strakes are once again driven against the wall by the uniquely shaped sail which extends upward at the end of the rotor. The sail actually catches the debris and directs into the strake at whatever location the debris is impacted.

Debris is stratified by strakes along entire length of ejection slotAll three strakes run the entire circumference of the dome and guide the debris to the ejection slot. The important thing to note is that the debris is stratified by these three strakes and is ejected along the entire length ejection slot.


All other Atmospheric ejective precleaners drive the debris into a single rotation pattern within the precleaner and force it out one specific location in the slot.

During heavy snowfall, some of the snow accumulates and recirculates within the precleaner because it cannot be ejected quickly enough and separating efficiency is lostThis accumulation of debris into a narrow band within the precleaner causes the precleaner ejection slot to clog quickly when there is a high volume of debris. Watery debris like snow, when amassed along a small area quickly, clogs the port. When a precleaner slot is clogged it allows the debris to pass into the air filter housing.

When the precleaner clogs in a dry debris environment the filter will get dirty more quickly, however, the filter remains dry. When this happens in a snow environment, the snow accumulates on the filter and melts then freezes and prevents air from passing through the filter. While it is never desirable for the ejection slot (port) to clog, it becomes a serious problem in snow environments when operator safety is involved.

The Series 9000 Precleaner is the only precleaner in the world which was designed by an aerospace engineer. The level of science which was incorporated into this precleaner is unprecedented in our industry. Understanding the importance of particle stratification within the precleaner was a key factor in the advancement of precleaning technology. This represents one of seven patented technologies incorporated into the Series 9000 precleaner design.

Stratification of the debris by the Series 9000 precleaner allows it to maintain separation efficiency, ejecting the debris along the entire ejection slot (port) without clogging even when processing large volumes of snow.

Part 4: Maintaining Operating Efficiency 

Previous: Part 2–The Prescreen



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