Set point adjust mechanism for process controllers

Apparatus for the simultaneous moving of a mechanically adjustable variable and a pointer both mechanically connected to a common toothed driven wheel to prevent dislocation between the pointer and the variable when the motion of either is impeded, the apparatus comprising:

• (a) a toothed driving wheel having an axle and adapted to engage the toothed driven wheel;
• (b) a notched lever adapted to engage said axle in the notch of said notched lever whereby said driving wheel is held in a first position;
• (c) bias means connected to said notched lever for releasably holding said notch against said axle, said bias means being adapted to allow said axle of said driving wheel to disengage said notch to allow said driving wheel to move normal to its axis from said first position to a second position in response to said driven wheel attaining a level of resistance to movement sufficient to cause said axle to overcome the force of said bias means and move out of said notch;
• (d) mechanical stop means for engaging the teeth of said driving wheel when said axle of said driving wheel is out of said notch and said driving wheel is in said second position;
• and,
• (e) a slider carrying said driving wheel and said notched lever, said slider being movable between a first position wherein said driving wheel engages the driven wheel and a second position wherein said driving wheel does not engage the driven wheel.

Apparatus for the simultaneous positioning of a mechanically adjusted variable and a pointer indicating on a scale the value or position of said variable and preventing dislocation between the pointer and the variable when the motion of either is impeded, the apparatus comprising:

• (a) a base plate;
• (b) a toothed drive wheel mounted on said base plate for rotary motion about an axle;
• (c) mechanical linkage means connecting said axle of said drive wheel to the shaft of the mechanically adjusted variable;
• (d) a toothed first pulley carried by said axle of said drive wheel;
• (e) a second pulley mounted on said base plate for rotary motion;
• (f) a toothed drive belt operably connected between said first pulley and said second pulley, said belt carrying the pointer adjacent the scale;
• (g) a slider mounted on said base plate in spaced relationship thereto and adapted for movement between a first position adjacent said drive wheel and a second position away from said drive wheel, said slider having a hole adjacent the edge of said slider closest said drive wheel;
• (h) a toothed thumbwheel mounted on said slider for rotary motion, said thumbwheel having an axle and being disposed with its axle adjacent the edge of said slider opposite said hole;
• (i) a notched lever mounted on said slider for pivotal motion about a pin, the notch in said lever being disposed over said hole and opening toward said thumbwheel;
• (j) a spring connected between said lever and said base plate, said spring urging said lever toward said thumbwheel, said spring further urging said slider away from said drive wheel;
• (k) a toothed idler wheel having an axle, said axle of said idler wheel passing through said hole in said slider and being engaged in said notch in said lever whereby said idler wheel will rotate with said axle in said notch when said thumbwheel is rotated, said idler wheel engaging said drive wheel when said slider in said position adjacent said drive wheel, said idler wheel adapted to overcome the force of said spring on said lever when the drive wheel attains a preselected level of resistance to rotation causing said axle of said idler wheel to move out of said notch and rotate about the periphery of said drive wheel;
• and,
• (l) a locking pin mounted on said base plate, said locking pin being disposed to clear the teeth of said idler wheel when said axle of said idler wheel is in said notch and engage the teeth of said idler wheel to prevent further rotation of said idler wheel when said axle of said idler wheel is out of said notch.