Rectangular hydraulic load cell

• US 3,889,529 A
• Filed: 04/17/1974
• Issued: 06/17/1975
• Est. Priority Date: 04/17/1974
• Status: Expired due to Term

• Current Assignee: Chester D. Bradley
• Original Assignee: Chester D. Bradley
• Inventors: Bradley, Chester D.
• Primary Examiner(s): Gill, James J.
• Application Number:
  US05/461,587
• Time in Patent Office: 426 Days
• Field of Search: 73/141R 177/208
• US Class Current: 73/862.581
• CPC Class Codes: G01G 5/003 load-cell construction or mountings
• CPC Class Codes: G01L 1/02 by hydraulic or pneumatic means

Abstract

A rectangular hydraulic load cell having a length greater than its width to maintain substantial acting area for high load capacity in narrow locations. The force is transmitted from a load bearing column to a steel diaphragm over the oil reservoir with four bridging members having precise 45* cuts at their ends to reduce friction as the bridging members move under load. Pivot strips with hardened pivot wires are provided which bear upon the upper surface of the bridging members. For precise lateral positioning of the cell column, spacer strips are secured to the casing around the bridging members to form a rectangular lateral bearing surface for the bridging members.

Claims

1. A hydraulic load cell comprising, in combination:

A. a base member 1. having means forming a rectangular fluid reservoir therein, 2. and having outlet means connectable to a pressure transducer;

B. a thin flexible diaphragm overlaying said fluid reservoir means;

C. means for securing said diaphragm to said base to contain fluid under pressure;

D. a column positioned over said diaphragm, 1. said column having a lower portion adjacent said diaphragm of rectangular configuration and generally conforming to the shape of said fluid reservoir means, 2. said lower column portion having means forming an extending portion to form shoulders around the periphery of said lower portion, said shoulders having a substantially vertical and a substantially horizontal surface;

E. a casing surrounding said lower column portion, 1. said casing being of a rectangular configuration, 2. and having shoulders around its lower end in substantially horizontal alignment with said column shoulders, said shoulders having substantially vertical and substantially horizontal surfaces;

F. four elongated bridging members positioned around said column between the shoulders of said column and the shoulders of said casing ring, 1. said bridging members each having 45* angles at their ends to provide essentially continuous bridging in a rectangular configuration between said casing and said column; and

G. low friction pivot means between said horizontal surfaces of said column shoulders and said bridging members and between said horizontal surfaces of said casing shoulders and said bridging members.

2. The hydraulic load cell defined in claim 1 wherein said pivot means comprises a plurality of elongated bearing strips interposed between said horizontal surface of said column shoulders and between said horizontal surfaces of said casing shoulders, said bearing strips having a hardened, rounded lower edge bearing on said bridging members.

3. The hydraulic load cell defined in claim 2 wherein said lower edge of said elongated bearing strips comprises means forming a shoulder portion along said lower edge and a round hardened wire positioned on said shoulder, said wire having a diameter greater than the depth of said shoulder and extending substantially the length of said strip.

4. The hydraulic load cell defined in claim 1 wherein said base is also of rectangular configuration and the length of said reservoir is substantially greater than its width to provide substantial acting area in said load cell for a given transverse dimension.

5. The hydraulic load cell defined in claim 1 wherein there are provided spacer strips between said casing shoulder and said bridging members, said spacer strips closely fitting into the casing shoulder to provide a substantially rectangular bearing surface for lateral retention of said bridging members.

6. The hydraulic load cell defined in claim 3 wherein the width of said bearing strip shoulder portions are less than the diameter of said wire and there is further provided means securing said strips to said column and to said casing to clamp and retain said wires.