About Reciprocating Rake Bar Screens

With this arrangement, the entire rake assembly is mounted on the cog wheel that moves on a fixed pin or gear rack. 

The reciprocating rake bar screen is equipped with a function that instructs the rake to ride over any barriers in its path while cleaning the bar screen. In the event that the rake mechanism becomes jammed, the unit will automatically shut off the motor.

The reciprocating rake bar screen is popular because all of the mechanical parts that require maintenance are above the water surface. This provision allows for easy access for inspection and maintenance, without the need to isolate and dewater the channel. This type of bar screen works very well in heavy duty applications, particularly combined sewer systems. But there are some drawbacks to using this type of bar screen.

For starters, this unit is equipped with only one raking mechanism instead of mutliple cleaning mechanisms as compared to other types of bar screens. Because of the one rake feature, this type of bar screen has limited capacity when it comes to heavy solids handling.

This is especially true in very deep channel where a very long reach is required and cycle times are long. As the rake begins to ascend to the top of the bar screens, solids will already start to accumulated on the face of the bar screen. This may potentially increase the head loss through the bar screen, thus having an effect on upstream processes. Another drawback to the reciprocating rake bar screen is the enormous amount of overhead clearance required to house the raking mechanism. The overhead clearance requirement greatly exceeds that of other types of bar screens. This requirement can be estimated by adding the vertical depth of the bar screen to the screenings discharge elevation above grade. Because of the clearance requirements, this screen is not the most popular pick in a retrofit application.