# US 11,027,834 B2 · Inboard centrifugal force bearing attachment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,027,834 B2 - Document ID: US11027834B2 - Status: Granted - Kind: B2 - Application number: 15/902,402 - Filed: 2018-02-22 - Published: 2019-08-22 - Granted: 2021-06-08 - Earliest claimed: 2018-02-22 - Assignees: Textron Innovations Inc. - Applicants: Textron Innovations Inc. - Inventors: Andrew Maresh; Troy Cyril Schank; Chyausong Tzeng; John Richard McCullough; Robert Wardlaw - Web page: https://patentgrep.com/patent/US11027834B2 ## CPC - B64C 27/48: Root attachment to rotor head - F16F 15/127: using plastics springs combined with other types of springs - B64C 3/32: specially adapted for mounting power plant - B64C 27/35: having elastomeric joints - B64C 29/0033: {the propellers being tiltable relative to the fuselage} - F16F 1/3842: {Method of assembly, production or treatment; Mounting thereof (supports for pipes, cables or protective tubing F16L3/00)} - B64C 2027/4736: {from composite materials} - B64C: AEROPLANES; HELICOPTERS - F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION ## Abstract An inboard bearing attachment for carrying centrifugal force (“CF”) loads in a rotor blade assembly of a rotorcraft includes a CF fitting having a curved surface and a shear bearing retainer aligned with the curved surface. A mounting flange connected to either the CF fitting or the shear bearing retainer is used to mount the inboard bearing attachment to a yoke. ## Claims ### Claim 1 A rotor system for a rotorcraft comprising: a yoke including a yoke arm having an outboard tip, the yoke arm forming a cut-out inboard of the outboard tip; a shear bearing; a centrifugal force bearing; and an inboard bearing attachment disposed in the cut-out of the yoke arm, the inboard bearing attachment comprising: a centrifugal force fitting including a block abutting the centrifugal force bearing having top and bottom sides and leading and lagging edges, the centrifugal force fitting including a mounting plate on one of the top or bottom sides of the block, the mounting plate extending beyond the leading and lagging edges of the block to form at least one leading mounting hole adjacent to the leading edge of the block and at least one lagging mounting hole adjacent to the lagging edge of the block, the mounting plate configured to mount to the yoke arm via the leading and lagging mounting holes; and a shear bearing retainer forming a hollow cylinder axially aligned with the block, the hollow cylinder having an interior cylindrical surface configured to encompass the shear bearing, the hollow cylinder having a leading side and a lagging side; wherein, the shear bearing retainer includes a leading flange protruding from the leading side of the hollow cylinder to form at least one second leading mounting hole and a lagging flange protruding from the lagging side of the hollow cylinder to form at least one second lagging mounting hole, the leading and lagging flanges curving in an inboard direction such that the second mounting holes are inboard of the hollow cylinder; and wherein, the top and bottom sides and the leading and lagging edges of the block are curved to form a circle. ### Claim 2 (depends on 1) The rotor system as recited in claim 1 wherein the centrifugal force fitting is a unitary piece with the mounting plate. ### Claim 3 (depends on 1) The rotor system as recited in claim 1 wherein the mounting plate forms a plurality of leading mounting holes and a plurality of lagging mounting holes. ### Claim 4 (depends on 1) The rotor system as recited in claim 1 wherein the shear bearing retainer includes upper and lower leading flanges and upper and lower lagging flanges. ### Claim 5 (depends on 1) The rotor system as recited in claim 1 wherein a centrifugal force load path extends through the centrifugal force fitting and the yoke arm inboard of the tip. ### Claim 6 (depends on 1) The rotor system as recited in claim 1 wherein the block has an inboard side forming a curved surface. ### Claim 7 (depends on 1) The rotor system as recited in claim 1 wherein the block has an inboard side forming a conical surface. ### Claim 8 (depends on 1) The rotor system as recited in claim 1 wherein the block has an inboard side forming a parabolic surface. ### Claim 9 (depends on 5) The rotor system as recited in claim 5 wherein the centrifugal force fitting is connected to the yoke arm at a centrifugal force connection and the centrifugal force load path includes the centrifugal force connection. ### Claim 10 A tiltrotor aircraft comprising: a fuselage; a wing supported by the fuselage; and a rotor system coupled to the wing, the rotor system comprising: a yoke including a yoke arm having an outboard tip, the yoke arm forming a cut-out inboard of the outboard tip; a shear bearing; a centrifugal force bearing; and an inboard bearing attachment disposed in the cut-out of the yoke arm, the inboard bearing attachment comprising: a centrifugal force fitting including a block abutting the centrifugal force bearing having top and bottom sides and leading and lagging edges, the centrifugal force fitting including a mounting plate on one of the top or bottom sides of the block, the mounting plate extending beyond the leading and lagging edges of the block to form at least one leading mounting hole adjacent to the leading edge of the block and at least one lagging mounting hole adjacent to the lagging edge of the block, the mounting plate configured to mount to the yoke arm via the leading and lagging mounting holes; and a shear bearing retainer forming a hollow cylinder axially aligned with the block, the hollow cylinder having an interior cylindrical surface configured to encompass the shear bearing, the hollow cylinder having a leading side and a lagging side; wherein, the shear bearing retainer includes a leading flange protruding from the leading side of the hollow cylinder to form at least one second leading mounting hole and a lagging flange protruding from the lagging side of the hollow cylinder to form at least one second lagging mounting hole, the leading and lagging flanges curving in an inboard direction such that the second mounting holes are inboard of the hollow cylinder; and wherein, the top and bottom sides and the leading and lagging edges of the block are curved to form a circle. ### Claim 11 (depends on 10) The tiltrotor aircraft of claim 10 wherein the mounting plate further comprises upper and lower mounting plates, the upper mounting plate coupled to the top side of the block and the lower mounting plate coupled to the bottom side of the block. ### Claim 12 (depends on 11) The tiltrotor aircraft of claim 11 wherein the upper and lower mounting plates are unitarily formed with the block. ### Claim 13 (depends on 11) The tiltrotor aircraft of claim 11 wherein the upper and lower mounting plates are separately connected to the block.