Pressure gauge

Claim 1

A gauge for measuring fluid pressure, said gauge comprising a dial plate provided with equally spaced pressure readings disposed around a face of said dial plate, a pointer to indicate said pressure readings, a rotatable member connected to said pointer for rotating said pointer above said face to a proper one of said readings, a plunger movable in a linear path in a direction of its axis, said plunger including a surface against which said fluid pressure is exerted, spring means exerting a spring pressure on said plunger which is in an opposite direction to said fluid pressure for determining movement of said plunger in said linear path to any one of predetermined positions corresponding to associated fluid pressures, said spring means having a spring characteristic which causes said predetermined positions to be non-proportional to said associated fluid pressures, one of said rotatable member and said plunger being provided with guide means corresponding to said spring characteristic for relating said non-proportional predetermined positions to radial positions which are proportional to said associated fluid pressures, and the other of said rotatable member and said plunger being provided with follower means engaging said guide means for rotating said rotatable member about said plunger axis with respect to said radial positions as said plunger moves in said linear path so that said pointer is rotated to one of said pressure readings corresponding to said fluid pressure acting against said plunger, said guide means including at least one groove, said follower means including at least one tab member engaging in said groove, said groove having varying degrees of slope with respect to said axis of said plunger, a degree of slope at one end of said guide means being greater than a degree of slope at an opposite end of said guide means to correspond to said spring characteristic.