The present invention relates to a shaft for a propulsion system configured to rotate a reducing mechanism about a rotational axis, the shaft comprising: —a first end configured to engage with an input gear of the reducing mechanism, —a first bellows and a second bellows, the first bellows and the second bellows being rotationally symmetrical about the rotational axis, the first bellows extending between the first end and the second bellows, and —a frustoconical body mechanically connecting the first bellows and the second bellows.

A robot joint 1 has two adjacent outer cylinders 3 and 5 and an inner cylinder 7 which extends inside the two outer cylinders and is provided with openings 9 in the cylinder wall. The inner cylinder 7 is connected via leaf springs 11, 13 to the two outer cylinders. The robot joint is provided with measuring means comprising markings 15 which are formed by holes 15 in the cylinder wall of one of the outer cylinders 3, as well as detection means 17, 19 for counting the number of markings that passes the detection means during rotation of the two outermost cylinders 3, 5 relative to each other, which detection means are connected to the other outer cylinder 5. By measuring the rotation of the outer cylinders relative to each other and linking it back to the robot arm drive, the consequences of the inaccuracies in the joint can be compensated.

An electric motor includes a rotor shaft, a first bearing, and a second bearing. The rotor shaft includes a first rotor shaft part and a second rotor shaft part, the first rotor shaft part being rotatably mounted via the first bearing, and the second rotor shaft part being rotatably mounted via the second bearing. A bellows is connected at its first axial end region to the first rotor shaft part, e.g., by welding, and the bellows is connected at its second axial end region to the second rotor shaft part, e.g., by welding.

A coupling structure includes a shaft, a tube, and a connection assembly. An end of the shaft is formed with a plurality of axial insertion troughs extended in an axial direction and arranged in an alternate manner. The tube includes a penetration-axle hole formed in a center thereof and corresponding to the penetration-axle section of the shaft. A plurality of radial insertion troughs, in the form of a recessed surface, are formed in an inner circumferential surface of the penetration-axle hole of the tube. The connection assembly includes a coupling block that has an outer circumference formed with a plurality of radial insertion blocks corresponding to the radial insertion troughs of the tube and a plurality of axial insertion blocks corresponding to the axial insertion troughs of the shaft, so that a fastening member may be used to selectively fasten the coupling block between the shaft and the tube.

In accordance with at least one aspect of this disclosure, a drive shaft includes, a first tube body having one or more first body channels defined through a wall thickness thereof, the one or more channels configured to increase bending and/or axial flexibility of the first tube body while only allowing for a less than proportional reduction in torsional stiffness of the first tube body. A second tube body can be concentrically disposed relative to the first tube body and connected to the first tube body at a first end portion and a second end portion. The second tube body can include one or more second body channels defined through a wall thickness thereof, the one or more channels configured to increase bending and/or axial flexibility of the second tube body while only allowing for a less than proportional reduction in torsional stiffness of the second tube body.

In accordance with at least one aspect of this disclosure, a drive shaft includes, a first tube body having one or more first body channels defined through a wall thickness thereof, the one or more channels configured to increase bending and/or axial flexibility of the first tube body while only allowing for a less than proportional reduction in torsional stiffness of the first tube body. A second tube body can be concentrically disposed relative to the first tube body and connected to the first tube body at a first end portion and a second end portion. The second tube body can include one or more second body channels defined through a wall thickness thereof, the one or more channels configured to increase bending and/or axial flexibility of the second tube body while only allowing for a less than proportional reduction in torsional stiffness of the second tube body.

A torque limiter (TL) is provided for torque transmission (TT) to downstream components. The TL includes an input shaft, an output shaft and a torsional spring which is preloadable by a preload torque whereupon the torsional spring is fittable about the output shaft with the output shaft fit about the input shaft. For input shaft rotation, first TT paths proceed from the input shaft to the output shaft through the torsional spring when downstream torque of the downstream components deceeds the preload torque and a second TT path proceeds from the input shaft to an external structure when the downstream torque exceeds the preload torque.

A torque limiter (TL) is provided for torque transmission (TT) to downstream components. The TL includes an input shaft, an output shaft and a torsional spring which is preloadable by a preload torque whereupon the torsional spring is fittable about the output shaft with the output shaft fit about the input shaft. For input shaft rotation, first TT paths proceed from the input shaft to the output shaft through the torsional spring when downstream torque of the downstream components deceeds the preload torque and a second TT path proceeds from the input shaft to an external structure when the downstream torque exceeds the preload torque.

A method of transmitting torque through a flexible coupling includes driving a first rotatable member with a second rotatable member, applying an axial force component to the a flexible coupling connecting the first rotatable member and the second rotatable member by changing an axial offset between the first rotatable member and the second rotatable member interconnected by the flexible coupling, reducing one or more of the axial force component and cyclic equivalent stress born by a flexible diaphragm body of the flexible coupling by axially shifting the first end of the flexible diaphragm body relative to one of the interconnected rotatable members, and affixing a splined member to a second end of the flexible coupling, wherein the flexible diaphragm body has an inner diameter that is greater than an inner diameter of the splined member.

A method of transmitting torque through a flexible coupling includes driving a first rotatable member with a second rotatable member, applying an axial force component to the a flexible coupling connecting the first rotatable member and the second rotatable member by changing an axial offset between the first rotatable member and the second rotatable member interconnected by the flexible coupling, reducing one or more of the axial force component and cyclic equivalent stress born by a flexible diaphragm body of the flexible coupling by axially shifting the first end of the flexible diaphragm body relative to one of the interconnected rotatable members, and affixing a splined member to a second end of the flexible coupling, wherein the flexible diaphragm body has an inner diameter that is greater than an inner diameter of the splined member.