Bezel and front cover (with set point knobs and zero adjustment screw) removed to expose Photohelic® switch/gage set point mechanism (cover is clear polycarbonate plastic)
Gauge pointer and light shutter are mounted on helix and balancing counterweight
Shutter passes through slot in optical limit switch to expose phototransistors to integral infrared light source or mask them depending on applied pressure
Light shield effectively protects phototransistors from strong outside light sources yet allows free pointer movement; it also gives interior a clean "finished" look
Optical limit switches are used for reliability and long service life. Attached directly to set pointers, they are individually aligned to assure precise switching accuracy
Semi-flexible drive shaft connects to set point knobs
Zero adjustment screw connects to screw in cover to adjust zero pressure reading
Plastic enclosure protects electronic components and electrical connections
Polycarbonate connection or terminal board is self-extinguishing
Glass epoxy printed circuit boards for durability and permanence
Load relays are DPDT with latching feature for maximum application versatility
Electronics are designed to operate on 50/60 Hz, 120 volt current with 10% over or under voltage
Switch set pointers show switch settings at all times
Spring loaded friction clutch prevents operator damage of set point mechanism
3-in-1 instrument allows the reduction of several instruments with one product
Unique design and 1% full scale dead band provides quick response to pressure changes means no delay in switching and chatter-free operation