# US 4,399,718 A · Pivot drive for manipulator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,399,718 A - Document ID: US4399718A - Status: Granted - Kind: A - Application number: 06/267,756 - Filed: 1981-05-28 - Granted: 1983-08-23 - Earliest claimed: 1980-05-29 - Assignees: Kuka Schweissanlagen & Roboter GmbH - Inventors: Ernst Zimmer - Web page: https://patentgrep.com/patent/US4399718A ## CPC - B25J 17/02: Wrist joints - B25J 9/102: {Gears specially adapted therefor, e.g. reduction gears (gearings in general F16H)} - B25J 9/1025: {Harmonic drives (in general: F16H49/001)} - B25J 19/002: {using counterweights} - Y10T 74/1957: Parallel shafts - Y10T 74/19623: Backlash take-up - Y10T 74/19628: Pressure distributing - B25J: MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES ({manipulators specially adapted for use in surgery A61B34/70; manipulators used in cleaning hollow articles B08B9/04}; manipulators associated with rolling mills B21B39/20; manipulators associated with forging machines B21J13/10; {manipulators associated with picking-up and placing mechanisms B23P19/007}; means for holding wheels or parts thereof B60B30/00; {vehicles with ground-engaging propulsion means, e.g. walking members B62D57/02, B62D57/032; devices for picking-up and depositing articles or materials between conveyors B65G47/90, B65G47/91; manipulators with gripping or holding means for transferring packages B65H67/065}; cranes B66C; {manipulators used in the protection or supervision of pipe-line installations F17D5/00; walking equipment adapted for nuclear steam-generators F22B37/006}; manipulators specially adapted for, or associated with, nuclear reactors G21C; {apparatus used for handling wafers during manufacture or treatment of semiconductor H10P72/50}) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A pivot drive for interconnecting a pair of members that are relatively pivotal about a pivot axis has a torsion rod extending along a rod axis and rotatable by an appropriate drive relative to one of the members. This rod has outer ends carrying input gears of respective constant-mesh gear trains having output gears at least one of which is limitedly rotatable about the pivot axis on the other member. This one output gear can be limitedly rotated and locked in place in the other member so as torsionally to prestress the rod, thereby eliminating play from the drive by bringing the gears of one of the gear trains into snug contact in one direction and the gears of the other gear train into snug contact in the opposite directions. ## Claims ### Claim 1 A pivot drive for interconnecting a pair of members that are relatively pivotal about a pivot axis, said drive comprising: a torsion rod extending along a rod axis and having outer ends; drive means for rotating said rod about said rod axis relative to one of said members; respective constant-mesh gear trains including respective input gears fixed on said outer ends and respective output gears connected to the other of said members and having respective centers, at least one of said output gears being limitedly angularly displaceable about the respective center relative to said other member; and means for rotating said one output gear relative to said other member about the respective center and thereby torsionally prestressing said rod and for locking said one output gear in position with said torsion rod prestressed. ### Claim 2 (depends on 1) The drive defined in claim 1 wherein said centers form an output-gear axis and all of said axes are coaxial. ### Claim 3 (depends on 2) The drive defined in claim 2 wherein said other member is carried on said output gears. ### Claim 4 (depends on 3) The drive defined in claim 3 wherein said one output gear is formed relative to the respective center with a tangentially extending surface, said means for rotating including: a bar lying on said surface and having bar ends; and respective bolts threaded in said other member and bearing in a direction generally toward the respective center on said bar ends, whereby said bolts can be screwed in said other member to displace said bar ends relative to said other member and to rotate said one output gear in said other member about the respective center. ### Claim 5 (depends on 2) The drive defined in claim 2 wherein said other member is forked and has a pair of axially spaced sides respectively holding said gear trains. ### Claim 6 (depends on 2) The drive defined in claim 2 wherein said drive means is connected to said torsion rod between said outer ends thereof. ### Claim 7 (depends on 6) The drive defined in claim 6 wherein said torsion rod has a pair of halves respectively having said outer ends and joined together between said outer ends at a geometric center, said drive means being connected to said rod at said geometric center. ### Claim 8 (depends on 7) The drive defined in claim 7 wherein at least one of said halves is a tube shaft, said drive means including a drive shaft extending coaxially through said tube shaft to said geometric center. ### Claim 9 (depends on 8) The drive defined in claim 8 wherein said halves are splined onto said drive shaft at said geometric center. ### Claim 10 (depends on 9) The drive defined in claim 9 wherein said halves are substantially identical tube shafts. ### Claim 11 (depends on 9) The drive defined in claim 9 wherein said drive means includes a bearing between said outer end of said tube shaft and said drive shaft. ### Claim 12 (depends on 1) The drive defined in claim 1 wherein said centers define an output-gear axis, said pivot axis coinciding with one of said rod and output-gear axes. ### Claim 13 (depends on 1) The drive defined in claim 1 wherein said gear trains are planetary-gear assemblies. ### Claim 14 (depends on 13) The drive defined in claim 13 wherein said assemblies each have: a sun gear constituting the respective input gear, a planet carrier constituting the respective output gear, a plurality of planet gears carried by said carrier and meshing with said sun gear, and a ring gear meshing with said planet gears and fixed on said one member.