The heading machines used in tunnel construction and mining are exposed to the most extreme loads.

The Problem
On the mechanical seal solution required by the customer it was necessary not only to support the entire head system but also to spray segments of the cutting drill head with water at a pressure of up to 70 bar accurately at the point of cutting. 

The DEPAC Solution
For this solution DEPAC developed a complex overall concept covering various functions.
The water pressure of up to 70 bar is sealed off between the inner and outer pair of seals. The water in this space between the two pairs of seals is distributed over 16 boreboles around the circumference of the rotating disk. Using a spring-loaded segment the flow of liquid is controlled such that only 30 % of the holes are open at any one time. As the result, the liquid always emerges in the same angle range at any rotary position.

An additional function of this package was to support the mechanical seal with an axially adjustable housing cover that enables "blind" fitting with axial tolerances of up to ± 2 mm.