Raked Bar Screens
The HUBER RakeMax® Raked Bar Screen is one of the range of high quality German manufactured screens designed specifically to process wastewater with high levels of solids and gross material.
Over 100 different types of HUBER screens have been installed in Australia and recently ten HUBER RakeMax® units have been supplied to the world’s largest sewage treatment plant in Mexico.
HUBER’s RakeMax® Raked Bar Screen is a heavy duty screen designed to process wastewater with high levels of solids and/or gross material. The screening medium is effectively a row of bars that can be spaced from 6mm to 50mm in channels up to 4m width to suit specific requirements. Channel depths of up to 20m are possible with the RakeMax®. A rake system is used to clear the bars of screened material and transport the screenings to a discharge chute using a specially designed wiper that ensures that the bars are properly cleared.
The screen is inclined at 75 degrees which is the ideal installation angle to allow the effective removal of a variety of solids from small twigs to trash and logs.
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The RakeMax® Screen is perfectly suited to virtually any municipal or industrial wastewater applications as the cleaning elements, attached to the chain system, can easily be adjusted to suit different requirements.
These elements can be conventional rakes, or brushes, or plastic wipers. As the cleaning elements are changeable, the screenings discharge capacity is then adjustable. This is especially favourable for high solids loads.
The RakeMax® bars have either a streamlined tear drop profile for spacings ≤ 12 mm, or a rectangular shape for spacing > 12 mm). The bar rack is an integral part of the sturdy frame, which ensures perfect meshing of the rake teeth with the bar spaces. Positive and reliable cleaning is thus guaranteed.
The installation height of the RakeMax® above ground level is very small and only dependent, even in case of deep channels, on the installation height of screenings transport or washing units.
Both ends of the cleaning elements are connected to drive chains. Each chain is driven by a sprocket on a common shaft and a flange mounted gear motor. Furthermore, defined meshing of the cleaning rakes with the bar rack ensures a high operating reliability. If the screen operation is blocked, a mechanical overload protection interrupts the operation.
The screening medium is a row of bars, spaced at 6—50mm. A rake system clears the bars and transports the screenings to the discharge wiper and gravitates from the machine’s discharge chute.
Chain rollers, made of wear-resistant polyamide, guide the chains exactly within the frame. The chains are driven by a pair of cogwheels. The plastic rollers also prevent wear between the chains and the cogwheels. The drive is connected with the frame through a spring; if the torque exceeds a certain value, due to any obstruction in the bar rack, a switch is pushed and the movement is reversed back and forth until the obstruction is loosened. Should the obstruction persist several reversals, an alarm is triggered. Self-destruction of the screen is thus prevented.
A multitude of rake bars are bolted at selectable distances to a pair of drive chains. With short distances between its rakes, the RakeMax® is able to remove extremely high screenings loads. The rake blades are made of sections that are bolted to the rake bars, thus facilitating easy replacement of a segment in case that its teeth should become damaged or worn.
Chains and cogwheels are made of hardened, zinc galvanized and chromated steel to combine great wear resistance with excellent corrosion-protection.
- The benefits of the RakeMax® Screen at a glance:
- Easy-to-retrofit into existing channels, installation without channel recesses possible
- Completely odour-encased screen with easy to remove covers
- Compact design with a low installation height above ground level
- Simple and easy-to-access chain tensioning unit
- All parts in contact with medium (except the chain, drive and bearing) are made of immersion pickled stainless steel. (Optional stainless steel chains available).
- Very low head loss with high separation efficiency
- High screenings discharge capacity through adjustable cleaning elements
- Screen installation is possible without a bottom step
- The screen consists of a self-supporting folded stainless steel profile so that it can easily be lifted out of the channel.
- Not hindered by gravel or grit
- Defined meshing of the cleaning rakes with the bar rack ensures a high operating reliability.
- Independently replaceable rake and comb plates
- There are several hundred RakeMax configurations available based on the 14 models available so each unit is designed specifically to suit the individual application.
- Channel width; 500mm – 4000mm
- Capacity: up to 3000L/s subject to wastewater quality
- Discharge height above channel floor; 2.2m to 20m
- Bar spacing: 6 – 50mm
- Installation angle: 70 – 85 degrees
