A positioning structure for a worm wheel which is configured to mesh with a worm spindle and contains: a body, a plurality of rolling assemblies, and at least one attaching material. The body includes plural accommodating grooves and plural recesses, wherein each recess forms on a bottom face of each accommodating groove and communicating with said each accommodating groove. Each rolling assembly includes a holder, a rolling ball, and a magnetic attracting element, wherein a width of the holder is less than a width of said each accommodating groove so as to form a gap between the holder and said each accommodating groove. Each attaching material is filled in the gap, and said each rolling assembly is adjustably moved to a fixing position of said each accommodating groove by using said each recess, such that said each attaching material locates the holder in said each accommodating groove.

A worm drive includes a rotatably mounted worm shaft, and a device for compensating an unwanted axial backlash of the worm shaft. The device for compensating the unwanted axial backlash of the worm shaft includes two pressure bodies between which the worm shaft is clamped in the axial direction by a diaphragm spring device. The diaphragm spring is assigned to one of the pressure bodies.

A tong for applying torque to a tubular and a method of using a tong, of which the tong includes a rotary ring defining an inner profile through which the tubular is received, the inner profile defining a plurality of pockets extending radially outward and a plurality of cam surfaces circumferentially between the plurality of pockets, and a plurality of engaging members disposed within the rotary ring. The plurality of engaging members are movable from a retracted position at least partially in the plurality of pockets to an engaging position in which the plurality of engaging members are positioned along the plurality of cam surfaces. The tong also includes a plurality of cam followers extending through the rotary ring, and a worm drive including a helical ridge. The plurality of cam followers engage the helical ridge so as to transmit a substantially tangential force to the rotary ring.

The present invention relates to a grease application device in which a tip-side inclined surface of a nozzle 28 is made to closely face worm wheel teeth 11 of a shaft-mounted worm wheel 9 while rotating the shaft-mounted worm wheel 9 by means of a drive unit 12. At this state, the grease application device is configured to apply liquid grease from a tip-side opening of the nozzle 28 to the worm wheel teeth 11 of the shaft-mounted worm wheel 9 and to apply the grease while pushing the grease into concave portions of the worm wheel teeth 11. Also, the grease application device is configured to end the application of the grease at a point of time at which the shaft-mounted worm wheel has rotated one revolution with respect to the nozzle 28 after starting the application of the grease to the shaft-mounted worm wheel 9.

A worm gear assembly may include an input shaft having a first and second screw formed axially thereon, a first torque transfer unit comprising a first worm wheel operatively coupled to the first worm screw, a first radial pinion coaxially affixed to the first worm wheel, and a first axial crown wheel operatively coupled to the first radial pinion, and a second torque transfer unit comprising a second worm wheel operatively coupled to the second worm screw, a second radial pinion coaxially affixed to the second worm wheel, and a second axial crown wheel operatively coupled to the second radial pinion, wherein the first radial pinion is in meshed interface with the second radial pinion, and wherein torque differences between the first axial crown wheel and the second axial crown wheel are transmitted at least in part through said meshed interface.

A dual rotary cam may include a first rotating unit, a second rotating unit, a first rod, a second rod and a transmission device. The transmission device has an active gear, two connecting gears, and two passive gears. The active gear is driven by a motor to drive the connecting gears. A decelerating gear that is co-axially disposed with the connecting gear is used to connect the passive gears. The passive gears co-axially connect with the connecting portions of the first rod and second rod. The gear motion between the active gear, connecting gears, passive gears and decelerating gear can be arranged to adjust the gaps therebetween to achieve a goal of seamless transmission of the rotary cam.

A rotating device includes a rotating disc and a combined transmission shaft. The rotating disc includes a turret and multiple driven rollers. The combined transmission shaft includes a first roller gear cam and a second roller gear cam. The first roller gear cam includes a first shaft, a combined shaft and a first helical tooth. The combined shaft protrudes outward from a side of the first shaft. The first shaft is surrounded by the first helical tooth and has a first outer surface and a first inner surface. The second roller gear cam includes a second shaft and a second helical tooth. The second shaft has a combination hole. The second shaft is surrounded by the second helical tooth and has a second outer surface and a second inner surface. The combined shaft passes through the combination hole.

A positioning structure for a worm wheel which is configured to mesh with a worm spindle and contains: a body, a plurality of rolling assemblies, and at least one attaching material. The body includes plural accommodating grooves and plural recesses, wherein each recess forms on a bottom face of each accommodating groove and communicating with said each accommodating groove. Each rolling assembly includes a holder, a rolling ball, and a magnetic attracting element, wherein a width of the holder is less than a width of said each accommodating groove so as to form a gap between the holder and said each accommodating groove. Each attaching material is filled in the gap, and said each rolling assembly is adjustably moved to a fixing position of said each accommodating groove by using said each recess, such that said each attaching material locates the holder in said each accommodating groove.

A cam mechanism includes a base, a roller gear, and a camshaft. The roller gear and the camshaft are rotatably supported by the base. The roller gear has a turret and a plurality of cam followers mounted on the circumference of the turret. The camshaft has a shaft portion and a tapered rib having a first tapered rib and a second tapered rib. The first and second tapered ribs are each engaged with the cam followers. The first and second tapered ribs are configured to rotate relative to each other around a rotation axis of the shaft portion during adjustment of preload at which the first and second tapered ribs are pressed against the cam followers. After the adjustment of the preload, the second tapered rib is fixed to the shaft portion, and the first and second tapered ribs are prevented from rotating relatively.