US 4,223,752 A · Scale employing wheatstone-type bridges and strain gages

Abstract

A scale including a rectangular base frame supporting on opposite sides horizontally disposed torsion bars having their central portions secured to said frame and including a horizontal, plate-like rectangular platform superposed to said frame and bars. End portion of said bars support said platform by upstanding, threaded members engaged in said bars, eccentric seats on threaded member heads, and balls on said seats on which the platform rests. General platform leveling can be achieved by full-turn rotation of the threaded members and scale calibration adjustment can be facilitated by less than full-turn adjustment of said threaded members thereby shifting the locations of the balls along the torsion bars. Each torsion bar end portion has an upper and a lower strain gage for a total of eight. Two modified Wheatstone bridges use the strain gages for all resistors of the bridges whereby all bridge resistors are active and the two bridges form the sole electrical means to measure load on the scale.

Claims8

Dependent claims

A scale, comprising:

(a) a platform and means supporting said platform including load measuring means that includes eight strain gages in which four gages are under tension and four gages are under compression responsive to load applied to said platform,
(b) two electrical Wheatstone bridges each of the type having four resistors, and said eight strain gages forming said resistors for said bridges whereby all of said resistors are active, said bridges having a joint voltage output signal proportional to said load, said two bridges forming the sole electrical Wheatstone bridge means to measure load of said scale,
(c) said strain gages being arranged in pairs with one of the pair in tension and one in compression and there being torsion bar means associated with each pair of gages in which a torsion bar end portion is disposed in horizontally cantilevered position, said gages under compression being on one side of said torsion bar end portions and said gages under tension being on the opposite side of said torsion bar end portions, and
(d) said load measuring means including a load transferring mounting associated with each torsion bar end portion that is adjustable therealong in scale calibration.

1 more element

A scale, comprising:

(a) a plate-like generally rectangular platform,
(b) a pair of horizontally-disposed, parallel, juxtaposed, spaced torsion bars located under opposite sides of said platform,
(c) platform supporting means including means operative to apply platform load to the end portions of said torsion bars in four-corner disposition,
(d) an upper and a lower strain gage on each torsion bar end portion for a total of eight strain gages and two Wheatstone type bridges using said strain gages for all resistors of said bridges whereby all bridge resistors are active and said two bridges form the sole electrical Wheatstone bridge means to measure load of said scale,
(e) a base secured to the central portions of said torsion bars, and
(f) said platform supporting means including said torsion bar end portions each having an upstanding, rotatably adjusted, threaded member secured therein with a head having a seat eccentrically located relative to the axis of rotation of said threaded member and a ball located on said ball whereby general leveling of said platform can be achieved by rotary full-turn adjustment of said threaded members and whereby scale calibration adjustment can be facilitated by less than full-turn adjustment of said threaded members thereby shifting the locations of said balls along said torsion bars.

3 more elements

Dependencies are inferred from the claim text.

Scale employing wheatstone-type bridges and strain gages

Life of this patent

Scale employing wheatstone-type bridges and strain gages

Life of this patent

Abstract

Claims8