Maintenance
27
7.4
Cleaning the overflow valve
Turn off the vacuum pump, vent to atmospheric pressure and allow to cool.
Undo screws 141 and remove valve cover 140, observe O-ring 138.
Remove valve plate 139 from the overflow channel and dismantle it.
Clean guide pins of valve cover 140, dry them and sand them lightly using emery cloth
(180 grain); if necessary replace completely if severe grooves are present.
– Never oil the guide pin, that has an adverse effect on damping.
Clean all other parts, inspect for wear and exchange if necessary.
Fig. 14: Cleaning the overflow valve 33
138 O-ring
139 Valve plate
140 Valve cover
141 Screws
142 Protective tube
143 O-ring
144 Guide pin
145 Screws
146 O-ring
147 Pin
148 Pressure spring
149 Screw
150 Guide sleeve
