Bimetal thermal gauge having zero and full scale calibration means

Claim 1

A bimetal thermal gauge comprising a frame structure, a pointer shaft secured to said frame structure, a pointer rotatably mounted on said pointer shaft through a pointer bracket, said bracket having formed therein a longitudinally elongated slot, a first calibrating bracket rotatably mounted at one end portion on said frame structure through a first pivot, a second calibrating bracket rotatably connected at onE end to the other end portion of said first calibrating bracket through a second pivot, a generally U-shaped bimetal strip having an operating leg and a temperature-compensating leg, said temperature-compensating leg being rigidly connected at one end portion to the other end portion of said second calibrating bracket, a pin rigidly connected to the leading end of said operating leg and movably inserted into said slot, a winding which is wound on said operating leg and connected to an electric circuit having a variable resistor which is responsive to varying conditions of an object to be measured, and a scale plate bearing graduations having lower and upper limit lines and positioned relative to said pointer, said bimetal strip and said pin being moved in the substantially lengthwise direction of said bimetal strip for alignment of said pointer with respect to said upper limit line by rotating said first calibrating bracket and in a direction substantially perpendicular to said slot for alignment of said pointer with respect to said lower limit line by rotating said second calibrating bracket.