Cast stainless steel lower/upper sprocket


Headworks® Mahr Bar Screen sets the standard for the industry, even in the toughest of applications including deep channels, high flows, combined sewers and large debris. The Mahr Bar Screen is a front raked, front return bar screen with multiple rake bars mounted to chains located on each side of the self contained frame. The design eliminates the possibility of solids carry over and can easily be totally enclosed for odor control and improved hygiene.

Advances in water and wastewater treatment processes, increased regulations, and wide acceptance of MBR, MBBR, and IFAS treatment processes within the industry have driven the need for fine screening devices. For over twenty years, the Mahr Bar Screen, an all stainless steel, front raked, front return bar screen has been the benchmark in the industry for robust reliability. Even in the toughest applications, such as deep channels, high flows, combined sewers with large debris, Mahr Bar Screens operate consistently everyday. Robust craftsmanship reduces capital costs by delivering coarse bar screening durability combined with fine screen separation.

Mahr Bar screen installation


Evergreen Water Solutions is often asked how long MS Series Bar Screen equipment lasts – a question we still can’t answer. In over 20 years we have yet to see any of MS Series bar screens fail! Tried and tested screens have been operating in the field, trouble free, for decades. In 1980, the first Mahr Bar Screen was installed in Vienna, Austria, in a pump station under the Danube River. This very same screen is still in operation. The state of the art technology incorporated into our equipment today is based on many of the robust design traits as the original.

Jam Protection

The patented reversing feature automatically clears obstructions lodged in the screenfield over 90% of the time without operator involvement. The VFD and PLC controls sense the obstruction and reverse the rake direction. Thus, the rake above the obstruction is forced down on the jammed object. This reverse pressure either successfully dislodges the object or the cycle is repeated in the forward direction. This ‘shuttling’ motion is repeated up to four times. In the rare event that the obstruction remains, an alarm is initiated for the operator and the machine shuts down, protecting the equipment.

Easy Maintenance

The Mahr Bar Screen utilizes either a lower turnaround or a sprocket assembly. The lower sprocket assembly is an exclusive self-lubricating ceramic bearing. The assembly is maintenance free, highly wear resistant, and covered by a standard 5-year warranty. Units have been in operation for over 10 years without a single part being replaced.

Mahr screenfield and chain detail

Rake Operation

The multiple rake bar teeth positively engage with the screenfield bars, with openings as fine as 3/16" (4 mm). The rakes travel in a continuous circuit from the bottom of the channel, up the bar rack and past the debris plate. The screenings are simply scraped off the rake into the discharge chute and dropped into a conveyor, compactor or dumpster. The design eliminates the possibility of solids carryover and can easily be completely enclosed for improved odor control and hygiene.

Lowest Headloss in the Industry

Headworks was the first to standardize the use of tapered or trapezoidal shaped screenfield bars into the market. The shape of the bars, together with the rapid cleaning cycle, eliminates blinding factors. Thus, headloss across the screen can be as low as 2" (5cm) at 50 MGD (2 m3/s) or higher. The Mahr Bar Screen comes with patented replaceable bars.