A scissor gear assembly 1 has a main gear 3 and auxiliary gear 5 concentric to the main gear and in axial direction near the main gear. Further the assembly has a planar annular spring 7 being interrupted at one place. At the interruption the spring has two ends 7A and 7B. The spring is present between both gears and is with one end 7A connected to the main gear 3 and with the other end 7B to the auxiliary gear 5, so that both gears are connected to each other in rotation direction via the spring. Each end 7A, 7B of the spring is provided with an extension 9 forming extra mass. These extensions are each provided with a slot 13. Because of these extra masses the spring torque will vary depending on the rotational speed of the gear assembly.

A cylindrical double helix gear having an axis and a unitary gear arrangement extending about the axis, wherein the gear arrangement has two axially spaced gear portions with each gear portion comprising a plurality of gear teeth extending about a radial outer surface of the gear arrangement, wherein the gear portions are connected by a flexible spacer portion configured to allow relative movement between the gear portions.

A cylindrical double helix gear having an axis and a unitary gear arrangement extending about the axis, wherein the gear arrangement has two axially spaced gear portions with each gear portion comprising a plurality of gear teeth extending about a radial outer surface of the gear arrangement, wherein the gear portions are connected by a flexible spacer portion configured to allow relative movement between the gear portions.

Timepiece wheel with play take-up, including a toothing, each tooth of which includes first and second half-teeth each including a part of the tooth profile, and movable with respect to each other against elastic return means, the wheel including, axially stacked, a first and a second half-wheel respectively carrying the first and second half-teeth and having limited rotational mobility with respect to each other, about the axis of this toothing, and against the elastic return means, the toothing of each half-wheel overhanging the other half-wheel, each half-wheel including hollows inside each of which is movable an opposite half-tooth, between two successive half-teeth.

An idle gear assembly comprises an outer ring having gear teeth formed on an external surface thereof and engaged with a crank gear and any one of the left and right balance gears. A bearing includes an inner member and an outer member in a radial direction of the bearing and a plurality of rolling bodies disposed between the inner member and the outer member. A ring has elasticity in a radial direction thereof. A hub has a flange, which is in contact with the bearing, and a penetration hole. The flange and the penetration hole are formed at one side of the hub in an axial direction. A nut is inserted through another side and mounted at a hollow portion of the ring. A bolt is inserted through the insertion hole of the bearing, the penetration hole, and the nut and fixes the bearing and the hub.

An idle gear assembly comprises an outer ring having gear teeth formed on an external surface thereof and engaged with a crank gear and any one of the left and right balance gears. A bearing includes an inner member and an outer member in a radial direction of the bearing and a plurality of rolling bodies disposed between the inner member and the outer member. A ring has elasticity in a radial direction thereof. A hub has a flange, which is in contact with the bearing, and a penetration hole. The flange and the penetration hole are formed at one side of the hub in an axial direction. A nut is inserted through another side and mounted at a hollow portion of the ring. A bolt is inserted through the insertion hole of the bearing, the penetration hole, and the nut and fixes the bearing and the hub.

A gear assembly comprising first and second gears configured to mesh with each other, the first gear comprising inner and outer ring elements and a resilient ring element disposed between and coupled to the inner and outer ring elements, the outer ring element comprising first gear teeth which mesh with second gear teeth of the second gear, wherein the first and second gears each comprise a positioning ring axially spaced apart from the first and second gear teeth, the positioning rings being configured to engage each other and limit the position of the first and second gear teeth relative to each other.

A gear assembly comprising first and second gears configured to mesh with each other, the first gear comprising inner and outer ring elements and a resilient ring element disposed between and coupled to the inner and outer ring elements, the outer ring element comprising first gear teeth which mesh with second gear teeth of the second gear, wherein the first and second gears each comprise a positioning ring axially spaced apart from the first and second gear teeth, the positioning rings being configured to engage each other and limit the position of the first and second gear teeth relative to each other.

Disclosed herein is a joint unit including two facing gears that include respective two bevel gear members that face each other, and an intermediate gear that has a bevel gear member meshing with both the two bevel gear members. One of the two facing gears and the intermediate gear includes a first member including an inner circumferential portion of the bevel gear member of the one of the two facing gears and the intermediate gear; a second member including an outer circumferential portion of the bevel gear member of the one of the two facing gears and the intermediate gear; and a resilient member attached to one of the first member and the second member for normally urging the other of the first member and the second member to move in a direction along the directions of rotation of the one of the two facing gears and the intermediate gear.

Backlash is controlled in an opposed-piston engine that includes two crankshafts disposed in a parallel, spaced-apart relationship and a gear train coupling the first and second crankshafts, the gear train including a driving gear coupled to the first crankshaft and a split gear assembly engaged with the driving gear to transfer rotation from the driving gear to the split gear assembly. The split gear assembly includes first and second gears, a spring mechanism that acts to angularly offset the first gear relative to the second gear in a first direction, and a one-way clutch mechanism that prevents relative angular movement of the first gear relative to the second gear in a second direction opposite the first direction.