# US 8,539,843 B2 · Load indicator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,539,843 B2 - Document ID: US8539843B2 - Status: Granted - Kind: B2 - Application number: 12/678,970 - Filed: 2008-09-19 - Published: 2010-10-14 - Granted: 2013-09-24 - Earliest claimed: 2007-09-19 - Assignees: Messier-Dowty Limited - Applicants: Martyn Inns; Steve Smith - Inventors: Martyn Inns; Steve Smith - Web page: https://patentgrep.com/patent/US8539843B2 ## CPC - F16C 23/045: {for radial load mainly, e.g. radial spherical plain bearings} - B64C 25/00: Alighting gear (air-cushion alighting gear B60V3/08) - B64F 5/60: Testing or inspecting aircraft components or systems - F16C 11/045: {with at least a pair of arms pivoting relatively to at least one other arm, all arms being mounted on one pin (crank-pins F16C11/02)} - F16C 17/24: with devices affected by abnormal or undesired positions, e.g. for preventing overheating, for safety - G01L 5/0071: {Specific indicating arrangements, e.g. of overload} - B64D 2045/008: {Devices for detecting or indicating hard landing} - F16C 2326/43: Aeroplanes; Helicopters - F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS - B64C: AEROPLANES; HELICOPTERS - B64F: GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT ## Abstract A load indicator comprises a load bearing assembly of first and second load bearing members (23, 22) connected together to bear a lateral load applied to the first member (23), the first load bearing member defining a cavity (25) with the second load bearing member such that it is frangible above an indicator load, and the cavity (25) containing an indicator liquid which escapes from the cavity once the first load bearing member is fractured by said load. The load bearing members (22, 23) comprise cylindrical members arranged concentrically with the outer member (23) having a portion of reduced thickness to render it frangible and to define the cavity (25). The cavity (25) includes an internal volume within the second load bearing member (22). The load indicator may be configured as a load bearing pin to connect two components. ## Claims ### Claim 1 A load indicator comprising a load bearing assembly of first and second load bearing members connected together to bear a lateral load applied to the first member, wherein the first load bearing member defines a cavity with the second load bearing member such that it is frangible above an indicator load, and the cavity contains a flowable indicator which escapes from the cavity once the first load bearing member is fractured by said load, wherein the first load bearing member is tubular and receives the second load bearing member within the first load bearing member so that the first and second load bearing members engage via lands at opposite ends and are spaced apart in a central region to form the cavity, the second load bearing member being arranged to continue to support said load following the first load bearing member being fractured by said load. ### Claim 2 (depends on 1) A load indicator as claimed in claim 1 in which a portion of the first load bearing member is of a reduced thickness to render it frangible and to define the cavity. ### Claim 3 (depends on 2) A load indicator as claimed in claim 2 in which both load bearing members comprise cylindrical members arranged concentrically. ### Claim 4 (depends on 1) A load indicator as claimed in claim 1 in which the cavity includes an internal volume within the second load bearing member. ### Claim 5 (depends on 1) A load indicator as claimed in claim 1 configured as a load bearing pin to connect two components and to bear a load applied between the two components. ### Claim 6 (depends on 1) An assembly of two components and a load indicator configured as a load bearing pin as claimed in claim 1, the pin engaging a pair of lugs on one component in alignment with the lands, and a lug on the other component which lies between the pair of lugs, so as to be loaded by a lateral load when the first and second components are loaded in compression or tension. ### Claim 7 (depends on 6) An assembly as claimed in claim 6 in which the two components comprise components of an aircraft landing gear. ### Claim 8 (depends on 7) An assembly as claimed in claim 7 in which the two components comprise members of a side stay or an articulation joint or a towing connection. ### Claim 9 (depends on 1) A method of detecting a hard landing of an aircraft using a load indicator as claimed in claim 1. ### Claim 10 (depends on 1) A method of detecting an overload force in towing an aircraft using a load indicator as claimed in claim 1. ### Claim 11 (depends on 1) A load indicator as claimed in claim 1 in which the flowable indicator is an indicator liquid.