Every Cable Arm clamshell is equipped with a passive venting system.
This venting system serves 3 purposes:

Open While Lowering

While the bucket is being lowered, the vents open - allowing water to flow through. This allows the clamshell to quickly fall to the floor.

 

Closed When Raising

When the bucket is raised, the vents close - reducing the possibility of water washing material out of the bucket.

 

Drain Excess Water

Once the bucket reaches the surface, excess water is drained through the vents, avoiding excess dewatering costs.