Patent ID: 7635235

Claim:
A worm shaft coupling for connecting a driven shaft of a transmission mechanism and a coaxially arranged worm shaft of an extruder, the worm shaft coupling having: a driven shaft coupling peg, a worm shaft coupling peg, facing the driven shaft coupling peg, a coupling sleeve receiving the driven shaft and worm shaft coupling pegs and connecting them with rotational engagement by means of longitudinal teeth, a first threaded sleeve to rigidly connect the coupling sleeve to the driven shaft in a longitudinal direction thereof, said first threaded sleeve having a first internal thread that is screwed to a first external thread of the coupling sleeve, a second threaded sleeve to rigidly connect the coupling sleeve to the worm shaft in a longitudinal direction thereof, said second threaded sleeve having a second internal thread that is screwed to a second external thread of the coupling sleeve, the second internal thread has a first thread root and the second external thread has a second thread root, wherein the second external thread of the coupling sleeve is provided, in alternation, with first recesses and first threaded portions, the first recesses and the first threaded portions each extending over identical circumferential angles α and each of the first recesses extending radially to an axis of the worm shaft inwardly to the second thread root, wherein the second internal thread of the second threaded sleeve is provided, in alternation, with second recesses and second threaded portions, each extending over said identical circumferential angles α, and each of the second recesses extending radially to the axis outwardly to the first thread root, wherein an anti-twisting means is associated with the first and second threaded sleeves for preventing twisting of the threaded sleeves, wherein each anti-twisting means comprises a retaining ring arranged on the coupling sleeve, a rotationally engaged connection being formed between the retaining ring and one of the threaded sleeves by a recess and a locking projection engaging therewith, wherein in a position locked to a respective threaded sleeve, the respective retaining ring is secured to the coupling sleeve so as to prevent twisting of the threaded sleeves, and wherein the coupling sleeve is provided with a retaining pin which engages with an angular groove in the retaining ring, wherein the angular groove comprises a first groove leg which extends in the direction of the axis and a second groove leg which extends perpendicular to the first groove leg and wherein the retaining pin is engaged in said first groove leg.