A damper device includes a first member, a second member, an elastic member and a supporting member. The first member has two wall members separated from each other. The supporting member includes projections (preventing portion) that make contact with one of two wall portions (wall members) so as to prevent the supporting member and an elastic member from being inclined (falling, rotationally moving) in the axial direction.

A coupling includes a claw part and an intermediate piece. The intermediate piece includes a tube piece produced from aluminum or from an aluminum alloy, and a buffer part received in an end region of the tube piece and including elastic damping elements for receiving the claw part. The damping elements are surrounded by the end region radially at an outside in a circumferential direction. The buffer part includes a part which is different from the damping elements and is produced from a material of a brittleness which is greater than a brittleness of the tube piece.

A coupling for connection of an encoder to an electrical machine includes an encoder shaft end piece for coupling to a shaft of the encoder, and a machine shaft end piece for coupling to a shaft of the electrical machine. At least one of the end pieces has a carrier which is formed with a cavity filled with granular material, preferably steel powder, to effect a dampening of vibrations and impacts.

A system for hydraulically fracturing an underground formation in an oil or gas well, including a pump for pumping hydraulic fracturing fluid into the wellbore, the pump having a pump shaft, and an electric motor with a motor shaft mechanically attached to the pump to drive the pump. The system further includes a torsional coupling connecting the motor shaft to the pump shaft. The torsional coupling includes a motor component fixedly attached to the motor shaft and having motor coupling claws extending outwardly away from the motor shaft, and a pump component fixedly attached to the pump shaft of the pump and having pump coupling claws extending outwardly away from the pump shaft. The motor coupling claws engage with the pump coupling claws so that when the motor shaft and motor component rotate, such rotation causes the pump component and the pump shaft to rotate, thereby driving the pump.

A radially compliant connection includes an axis, a first plate with a first connection portion, a second plate with a second connection portion, an intermediate plate with third and fourth connection portions, a first flexible element fixed to the first connection portion and to the third connection portion, and a second flexible element fixed to the second connection portion and to the fourth connection portion. In some example embodiments, the first connection portion has a radially inner surface with a first radius, and the second connection portion has a first radially outer surface with a second radius, less than the first radius. In an example embodiment, the third connection portion has a second radially outer surface with a third radius, equal to the second radius, or the fourth connection portion has a third radially outer surface with a fourth radius, equal to the second radius.

A radially compliant connection includes an axis, a first plate with a first connection portion, a second plate with a second connection portion, an intermediate plate with third and fourth connection portions, a first flexible element fixed to the first connection portion and to the third connection portion, and a second flexible element fixed to the second connection portion and to the fourth connection portion. In some example embodiments, the first connection portion has a radially inner surface with a first radius, and the second connection portion has a first radially outer surface with a second radius, less than the first radius. In an example embodiment, the third connection portion has a second radially outer surface with a third radius, equal to the second radius, or the fourth connection portion has a third radially outer surface with a fourth radius, equal to the second radius.

A double cardan joint assembly including an input universal joint, an output universal joint, and a resilient member disposed between the input universal joint and the output universal joint. The resilient member is positioned between the input universal joint and the output universal joint by attachment to either an arc guard of each universal joint or a cross-member of each universal joint, for example. The resilient member is adapted to center and align the double cardan joint assembly. Thus, the double cardan joint assembly does not necessarily include a conventional aligning ball-joint.

A double cardan joint assembly including an input universal joint, an output universal joint, and a resilient member disposed between the input universal joint and the output universal joint. The resilient member is positioned between the input universal joint and the output universal joint by attachment to either an arc guard of each universal joint or a cross-member of each universal joint, for example. The resilient member is adapted to center and align the double cardan joint assembly. Thus, the double cardan joint assembly does not necessarily include a conventional aligning ball-joint.

A gearbox assembly includes a housing, a first shaft assembly having a worm gear and supported relative to the housing by a first bearing assembly, and a second shaft assembly including a wheel gear which is also supported relative to the housing by a second bearing assembly, the wheel gear engaging with the worm of the worm gear to permit the transfer of torque between the two shaft assemblies, wherein the first shaft assembly includes an elongate shaft carrying the worm gear, and a separate dog drive mechanism secured to one end of the elongate shaft by the first bearing such that in use torque is transferred between the elongate shaft and the dog drive mechanism.

A drive transmitter includes a first member and a second member. The first member includes an opening through which a rotary shaft passes, a wall orthogonal to an axial direction of the first member, and a drive transmitting portion by which a driving force is transmitted. The second member has a rigidity greater than the first member and is configured to be fastened to the first member. A space is between the second member and the first member, with the first member and the second member being overlaid in a fastening direction of the second member, prior to fastening of the first member and the second member. At least a part of the wall of the first member defining the space with the second member is configured to shift toward the second member to reduce a diameter of at least a part of the opening at the fastening.