# US 8,464,845 B2 · Master cylinder lever for a bicycle hydraulic disc brake > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,464,845 B2 - Document ID: US8464845B2 - Status: Granted - Kind: B2 - Application number: 13/324,868 - Filed: 2011-12-13 - Published: 2012-04-26 - Granted: 2013-06-18 - Earliest claimed: 2001-12-28 - Assignees: Sram, LLC - Applicants: Wayne R. Lumpkin - Inventors: Wayne R. Lumpkin - Web page: https://patentgrep.com/patent/US8464845B2 ## CPC - B60T 7/102: {by means of a tilting lever} - B60T 11/22: characterised by being integral with reservoir - B62L 3/023: {acting on fluid pressure systems} - B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES - B62L: BRAKES SPECIALLY ADAPTED FOR CYCLES {(arrangements in cycles for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions B60T8/00)} ## Abstract A master cylinder for a bicycle hydraulic disc brake configured to be disposed on either a right or left portion of a bicycle handlebar without effecting operation of the master cylinder by a user. ## Claims ### Claim 1 A master cylinder for a bicycle hydraulic disc brake comprising: a master cylinder housing; a lever handle pivotally connected to the master cylinder housing; a bar clamp attached to the master cylinder housing for attaching the master cylinder housing to a bicycle handlebar along a clamp axis; a cylinder wall associated with the master cylinder housing, the cylinder wall comprising a cylinder interior and a cylinder exterior extending axially of a cylinder axis, the cylinder having a first end and a second end and the cylinder axis being non-parallel to the clamp axis; a reservoir for hydraulic fluid associated with the master cylinder housing, the reservoir comprising a first wall comprising only a limited radial portion of the cylinder exterior and an elastomeric diaphragm, wherein the cylinder axis and the clamp axis lie in a plane intersecting the first wall, the cylinder axis being substantially perpendicular to the clamp axis and wherein the reservoir is disposed substantially entirely between the clamp axis and the lever handle; a port in the first wall between the first and second cylinder ends providing fluid communication between the reservoir and the cylinder interior, the first wall facing a direction the lever handle extends away from the master cylinder housing; and a piston within the cylinder having a seal operatively associated therewith, the piston being moveable along the cylinder axis between the first and second cylinder ends, the seal preventing flow of hydraulic fluid from the reservoir to the second cylinder end upon the seal advancing axially past the port as the piston moves from the first toward the second cylinder end, the master cylinder housing and the reservoir being configured such that the master cylinder may be operatively disposed on either a right or left portion of a handlebar of a bicycle without effecting operation of the master cylinder by a user. ### Claim 2 (depends on 1) The master cylinder of claim 1 wherein the first wall and the port are configured such that the master cylinder may be operatively disposed on either a right or left portion of a handlebar of a bicycle without effecting operation of the master cylinder by a user. ### Claim 3 (depends on 2) The master cylinder of claim 2 wherein the first wall and the port are configured to prevent air bubbles within the hydraulic fluid from entering the port such that the master cylinder may be operatively disposed on either a right or left portion of a handlebar of a bicycle without effecting operation of the master cylinder by a user. ### Claim 4 (depends on 1) The master cylinder of claim 1 further comprising the plane bisecting the first wall. ### Claim 5 (depends on 1) The master cylinder of claim 1 further comprising the first wall extending into the reservoir. ### Claim 6 (depends on 1) The master cylinder of claim 1 wherein the master cylinder further comprises an extension adjacent the port configured to prevent the elastomeric diaphragm from blocking the port. ### Claim 7 (depends on 1) The master cylinder of claim 1 further comprising a hydraulic line having an opening into the cylinder interior which is substantially opposite the first wall. ### Claim 8 A master cylinder for a bicycle hydraulic disc brake comprising: a master cylinder housing; a lever handle pivotally connected to the master cylinder housing such that actuation of the lever handle defines an arc of lever handle actuation with all points of actuation lying in a plane; a bar clamp attached to the master cylinder housing for attaching the master cylinder housing to a bicycle handlebar along a clamp axis; a cylinder wall associated with the master cylinder housing, the cylinder wall comprising a cylinder interior and a cylinder exterior extending axially of a cylinder axis, the cylinder having a first end and a second end and the cylinder axis being substantially perpendicular to the clamp axis; a reservoir for hydraulic fluid associated with the master cylinder housing, the reservoir comprising a first wall comprising only a limited radial portion of the cylinder exterior and an elastomeric diaphragm, wherein the cylinder axis and the clamp axis lie in a plane intersecting the first wall and wherein the reservoir is disposed substantially entirely between the clamp axis and the lever handle; a port in the first wall between the first and second cylinder ends providing fluid communication between the reservoir and the cylinder interior, the first wall facing a direction the lever handle extends away from the master cylinder housing; and a piston within the cylinder having a seal operatively associated therewith, the piston being moveable along the cylinder axis between the first and second cylinder ends, the seal preventing flow of hydraulic fluid from the reservoir to the second cylinder end upon the seal advancing axially past the port as the piston moves from the first toward the second cylinder end, the master cylinder housing and the reservoir being configured such that the master cylinder may be operatively disposed on either a right or left portion of a handlebar of a bicycle without effecting operation of the master cylinder by a user. ### Claim 9 (depends on 8) The master cylinder of claim 8 wherein the first wall and the port are configured such that the master cylinder may be operatively disposed on either a right or left portion of a handlebar of a bicycle without effecting operation of the master cylinder by a user. ### Claim 10 (depends on 9) The master cylinder of claim 9 wherein the first wall and the port are configured to prevent air bubbles within the hydraulic fluid from entering the port such that the master cylinder may be operatively disposed on either a right or left portion of a handlebar of a bicycle without effecting operation of the master cylinder by a user. ### Claim 11 (depends on 8) The master cylinder of claim 8 further comprising the plane bisecting the first wall. ### Claim 12 (depends on 8) The master cylinder of claim 8 further comprising the first wall extending into the reservoir. ### Claim 13 (depends on 8) The master cylinder of claim 8 wherein the master cylinder further comprises an extension adjacent the port configured to prevent the elastomeric diaphragm from blocking the port. ### Claim 14 (depends on 8) The master cylinder of claim 8 further comprising a hydraulic line having an opening into the cylinder interior which is substantially opposite the first wall.