Viry hydraulic screen rakes are designed for cleaning the screens upstream of a hydroelectric station. They are installed and maintained out of the water and do not require the water channel to be drained. The mobile versions can clean screens of unlimited width.

They comprise a welded base unit, a main jib and a raker jib, operated by hydraulic rams. The mobile version has a carriage driven by a hydraulic motor. 

OPERATION:

When not operating, both jibs are folded. When the machine is started, the raker jib deploys before the main jib descends to position the raker at the bottom of the screen. The raker then presses against the screen and rises to the level of the rubbish collector.

The automatic control system is triggered either by an adjustable timer which determines the frequency of cleaning, or by a system detecting clogging of the screens. Each movement in a cycle can also be controlled from a button unit.

SAFETY DEVICES:

The hydraulic generator is protected by level and temperature controllers, with a thermal relay for the pump motor. Any fault cuts off the electrical supply to the screen rake until an operator intervenes. All faults are reported by luminous or audible signals, which can be transmitted to a remote position. In the event of a blockage, the mobile rake moves on to the next position, whereas the fixed versions stops and waits for an operator intervention.

In both cases, the blockage is reported by an indicator lamp.

• either a channel with an immersed pump which is started when the screen rake starts.
• or a skip which moves with the mobile version of the screen rake.

• Cyrille SOMBRET
• Damien FISCHER