Load-measuring devices

Abstract

A load-measuring device, comprising a ring to be interposed between two opposed bodies coaxial with the load axis. Circumferentially-spaced projections separate one axial face of the ring from one of the bodies, and similar but angularly-staggered projections separate the other axial face from the other body, so that when the bodies approach under load the ring is distorted to an undulating shape. The distortion may be measured by a set of strain gauges fixed to the axial faces of the ring, and the output of a second set of gauges fixed to the radial faces of the ring may serve to compensate for distortions of the ring caused by things other than axial thrust, e.g. temperature variation. The projections may be fixed to the ring, or fixed to and located by the ring casing so that they bear against the ring in use.

We claim: .[.1. A load-measuring device comprising a ring-shaped body, 
     
        and second axial projections..]. .[.2.  A load-measuring device as claimed in claim 1 in which said first and second axial projections are integral with said ring-shaped body..]. .[.3. A load-measuring device according to claim 1 in which said first and second axial projections are bonded to said ring-shaped body..]. .[.4. A load-measuring device according to claim 1 including parts of said device other than said ring-shaped body on and 
     
     
        by which the said axial projections are mounted and located..]. 5. A load-measuring device according to claim .[.4.]. .Iadd.11 .Iaddend.including a two-part casing which encloses said ring-shaped body, and in which said other parts of said device are the said two parts of 
     
     
        said casing. 6. A load-measuring device according to claim .[.1.]. .Iadd.11 .Iaddend.in which said means to measure said strains in said ring-shaped body comprise a first set of gauges mounted on said ring-shaped body to measure the predominantly tensile bending strain 
     
     
        caused by said undulating distortion. 7. A load-measuring device according to claim 6, in which said first set of gauges are mounted on each of said axial faces of said ring-shaped body at points axially-opposite to where one of said projections bears against the opposite side axial face of said 
     
     
        ring-shaped body in use. 8. A ring load-measuring device according to claim 6, in which said ring-shaped body presents radially-inner and radially-outer faces in addition to said axial faces, and in which said means to detect said distortion includes a second set of gauges that are attached to said radially-inner and radially-outer faces at locations 
     
     
        circumferentially-staggered relative to those of said projections. 9. A load-measuring device according to claim 6 in which said gauges are of electrical resistance type so that the signal of a said gauge when it responds to said distortion corresponds to a change in the electrical 
     
     
        resistance of said gauge. 10. A load-measuring device according to claim 9 including a bridge-type electrical circuit, and in which said gauges are arranged within said circuit and the output of said circuit provides an 
     
     
        indication of the resultant of said opposed axial loads. .Iadd.11.  A load-measuring device comprising a ring-shaped body, at least three circumferentially-shaped first axial projections presenting sectorially-aligned surfaces operatively mounted so that said surfaces are movable relative to said ring-shaped body in a direction parallel to the axis of said body so as to engage a first of the two axial faces of said ring-shaped body;   at least three circumferentially-spaced second axial projections presenting sectorially-aligned surfaces operatively mounted so that said surfaces are movable relative to said ring-shaped body in a direction parallel to the axis of said body so as to engage the second and opposite of said axial faces of said ring-shaped body at locations staggered relative to those of said first axial projection;   means to detect the strain imposed upon said ring-shaped body when said ring-shaped body is distorted elastically to sectorially-undulating shape by opposed axial loads applied to said ring-shaped body through said first and second axial projections, said device further including parts of said device separated from said ring-shaped body on and by which the said axial   
     
     
        projections are mounted and located. .Iaddend. .Iadd.12.  A load-measuring device of ring-like form for interposition between two members to respond to a load urging those two members together, comprising: at least 3 circumferentially-spaced first load-transmitting elements located to bear against one axial face of said ring; at least 3 like second elements located to bear against the opposite axial face of said ring;   said locations of said first elements being circumferentially staggered relative to said locations of said second elements so that when said ring is interposed between said 2 members under load said members will bear in opposite axial directions against said ring by way of said first and second elements so as to distort said ring elastically to an undulating shape;   an array of strain-responsive gauges carried by said ring, said array being in two parts;   gauges within said first part being mounted upon said ring so that they measure the strains caused by the distortion of said ring; and   gauges within said second part being mounted on said ring to compensate for distortions of said ring other than those caused by said applied load, so that the output of said array of said gauges may provide an indication of   
     
     
        said applied load unaffected by said distortions. .Iaddend. .Iadd.13.  A load-measuring device according to claim 12 in which said gauges of said first part of said array are mounted on the axially-facing faces of said ring at locations axially-opposite to where one of said load transmitting elements bears against the opposite axially-facing face of said ring in use. .Iaddend. .Iadd.14. A load-measuring device according to claim 12 in which said gauges of said second part of said array are mounted on the radially-inward and radially-outward facing faces of said ring at locations circumferentially staggered relative to those said first and second load-transmitting elements. .Iaddend.