A fixed contact may be arranged so the switch will open or close on a temperature rise. This allows the switch contacts to be arranged to close when the temperature drops to a predetermined value and to open when the temperature rises to the desired value. The reverse action can be obtained by a change in the contact positions. This makes reading of the gauge not only difficult but often impossible. Pressure oscillations and other sudden pressure changes existing in fluid power systems will also affect the delicate internal mechanism of gauges and cause either damage to or complete destruction of the Figure 8-15.
Temperature switch with two types of sensing elements.
A. Bulb unit. B. Helix unit. A pressure gauge snubber is therefore installed in the line that leads to the pressure gauge. The purpose of the snubber is to dampen the oscillations and thus provide a steady reading and protection for the gauge. The snubbing action is obtained by metering fluid through the snubber.