Maintenance position

Maintenance position

The vacuum reaches chamber E from duct F (case I), since the force of spring (6) acts on mobile unit (4) and shunt valve (5) to open up the passage.

The vacuum passes through compensation port D to chamber B and the lower surfaces of the plate plunger (3).

Once the forces acting on plate (3) are balanced, the atmospheric pressure in duct A enters chamber B to move the mobile unit down (case II). The plunger of valve (5) then closes duct F and brings chamber E into communication with chamber C at atmospheric pressure to reduce the vacuum in duct E.

The reduced vacuum level or increase in absolute pressure in chamber E causes mobile unit (4) to lift (case I) to close passage C-E and restore valve (5) to ideal conditions (E in communication with F), to repeat the cycle.