Mechanical load measuring systems

Claim 2

A load measuring system comprising a weigh lever fulcrumed for angular displacement about an axis, means for applying a load to said weigh lever for exerting a turning moment about said fulcrum, spring resistant means exerting an opposite turning moment on said weigh lever, an indicating lever pivoted about a fixed axis, a scale operatively associated with said indicating lever, motion transmitting means connecting said weigh lever to said indicating lever so that said indicating lever is pivotally displaced by angular displacement of said weigh lever, and a compensating spring directly connected to said indicating lever for exerting a compensating moment that varies continually during angular displacement of said weigh lever to provide for equal incremental displacements of said indicating lever for equal increments of load applied to said weigh lever, said indicating lever being a bellcrank having one arm adapted to cooperate with said scale and the compensating spring being connected to the other arm of said bellcrank.

Claim 3

A mechanical load measuring system including a load bearing lever fulcrumed on a fixed frame, means for applying a load to be measured to said lever so as to exert a turning moment about the fulcruM, a spring resistant exerting an opposite turning moment on the lever, and measuring means responsive to the magnitude of angular displacement of the lever under load to provide a measure of magnitude of the load, characterized by an arm mounted for angular displacement about a fixed axis, means connected to said arm for effecting angular displacement of said arm by angular movement of said lever, and a compensating tension spring connected between a first anchorage on the frame and a second anchorage on said arm, whereby the tension of said compensating spring and the angular direction at which the force of said compensating spring is applied to the arm are both substantially varied during said angular displacement to apply a compensating moment which varies nonlinearly throughout at least a part of the operating range of the system and which is in opposition to a nonlinear error otherwise inherent in at least part of the range between the magnitude of the applied load and the measure of said load provided by said measuring means, and further characterized in that at one predetermined angular position of the lever the second anchorage may be brought into line with the first anchorage and said fixed axis whereby a zero compensating moment is applied at said position.

Claim 4

A mechanical load measuring system including a load bearing lever fulcrumed on a fixed frame, means for applying a load to be measured to said lever so as to exert a turning moment about the fulcruM, a spring resistant exerting an opposite turning moment on the lever, and measuring means responsive to the magnitude of angular displacement of the lever under load to provide a measure of magnitude of the load, characterized by an arm mounted for angular displacement about a fixed axis, means connected to said arm for effecting angular displacement of said arm by angular movement of said lever, and a compensating tension spring connected between a first anchorage on the frame and a second anchorage on said arm, whereby the tension of said compensating spring and the angular direction at which the force of said compensating spring is applied to the arm are both substantially varied during said angular displacement to apply a compensating moment which varies nonlinearly throughout at least a part of the operating range of the system and which is in opposition to a nonlinear error otherwise inherent in at least part of the range between the magnitude of the applied load and the measure of said load provided by said measuring means, and further characterized in that at one predetermined angular position of the lever the second anchorage may be brought into line with the first anchorage and said fixed axis whereby a zero compensating moment is applied at said position.

Claim 5

A load measuring system according to claim 2 characterized in that the resistant includes a tension spring adjustable so that the relationship between the magnitude of the applied load and the magnitude of the angular displacement of the lever is linear when said load is zero, half of full capacity, and full capacity, and the nonlinear error opposed by the compensating moment occurs in the ranges between said load values.

Claim 6

A load measuring system according to claim 2 characterized by means for adjustment of the angular displacement at which the compensating moment is applied to the lever.

Claim 7

A load measuring system according to claim 2 characterized in that the measuring means includes an optical projection system.

Claim 8

A load measuring system according to claim 2, wherein said zero compensating moment is applied when said lever is at a position determined by a load which is one-half of the full capacity of the system.

Claim 9

A load measuring system according to claim 2, wherein the measuring means includes an indicating lever linked to the load bearing lever, and the second anchorage of the compensating spring is on an arm of said indicating lever.

Claim 10

A load measuring system according to claim 2, wherein said zero compensating moment is applied at an angular position of the lever which is outside the normal and predetermined weighing range of the machine whereby the nonlinear compensation applied throughout said range is always of the same sign.

Claim 11

A load measuring system according to claim 2, wherein means is provided for adjustment of said arm about said fixed axis for varying the angular location of said arm relative to a part of the lever to which the load and resistant are applied.

Claim 12

A load measuring system according to claim 9, wherein said arm is carried by a rockable pivot member, and said adjustment comprises releasable clamp means connecting the arm to said pivot member.

Claim 13

A load measuring system according to claim 2 characterized in that the quantity of the compensating moment applied to the lever can be adjusted.

Claim 14

A load measuring system according to claim 10, characterized in that means for adjusting said quantity includes means for varying the distance between the second anchorage and the fixed axis of said arm.

Claim 15

A load measuring system according to claim 10 characterized in that means for adjusting said quantity includes means for varying the distance between the first anchorage on the frame and the fixed axis of said arm.

Claim 16

A load measuring system according to claim 11 characterized in that means for adjusting said quantity includes means for varying the tension of the compensating spring means.

Claim 17

A load measuring system according to claim 11 cHaracterized in that means for adjusting said quantity includes means for varying the stiffness of the compensating spring means.