Rakes are used in hydroelectric power plants and in wastewater treatment plants to retain coarse material that may damage the plant. Similar to piers, rakes constrict the flow cross-section possibly leading to backwaters. Depending on the bar spacing, the bar profile and the bar inclination, the backwater may be little or considerable.
The rake HM 161.38 enables to vary the rake flow resistance using different bar profiles and different angles of inclination. Three bar sets with different profiles are included.