A steering mechanism configured to rotate first and second axles relative to bogie-frame to perform steering; electric motors supported by bogie-frame, arranged at the front and rear sides in the car longitudinal direction, respectively, including output shafts, respectively, and output shafts being parallel to first and second axles at the time of non-steering; reducers connected to axles, respectively; and first constant velocity ball joint by which the first output shaft is coupled to the first reducer and which follows rotations of the first axle at the time of steering to allow relative displacement between the first output shaft and the first reducer, and a second constant velocity ball joint by which the second output shaft is coupled to the second reducer and which follows rotations of the second axle at the time of the steering to allow relative displacement between the second output shaft and the second reducer.

An adapter for use in a power system having a first powertrain joined to a second powertrain by a coupling. The adapter may have a generally cylindrical body having a central bore formed therein that is configured to receive a shaft of the first powertrain, and splines formed at an end of the central bore. The adapter may also have a connection keyway formed within an outer annular surface of the generally cylindrical body and configured to receive a key that engages the coupling, and a balancing keyway formed within the outer annular surface of the generally cylindrical body and configured to remain empty to balance the coupling.

A driving head-changeable tool includes an outer sleeve, an inner sleeve and a limitation mechanism. The outer sleeve defines a central axis and has an end peripheral edge having corner portions and blocking flanges therebetween and a circumferential sliding slot. The inner sleeve is rotatably sleeved by the outer sleeve and has first and second connecting ends. The first connecting end has axial concaves. The limitation mechanism is mounted to the inner sleeve and extends into and movable relative to the sliding slot. When the limitation mechanism is located in a lock position, the outer and inner sleeves are unrotatable relative to each other and each concave overlaps axially with one of the blocking flanges; when the limitation mechanism is located in a release position, the outer and inner sleeves are rotatable relative to each other and each concave corresponds to one of the corner portions.

A shaft (1) is shown comprising a shaft section (2) having an axis (3), a tooth geometry (4) at least at one end of said shaft section, said tooth geometry (4) having a first end (5) opposite said shaft section (2) and a second end (6) adjacent said shaft section (2), a number of teeth (7) distributed in circumferential direction around said axis (3), a bottom curve (9) between adjacent teeth (7), and an outer tooth curve (12), said bottom curve (9) having a positive slope from said first end (5) towards said shaft section (2) and a negative slope (14) at said second end (6). In such a shaft wear should be made as small as possible. To this end said bottom curve (9) comprises a section having a concave bottom curvature (15) between said positive slope and said negative slope.

A length adjustment for a drive shaft, wherein the length adjustment has the following: a first rotary element with a first longitudinal toothing and a second rotary element with a second longitudinal toothing. The first longitudinal toothing and the second longitudinal toothing mesh with each other and are axially displaceable to each other. In an end portion of the first rotary element a tooth gap between two longitudinal teeth of the first longitudinal toothing is obstructed. The radial height of a longitudinal tooth of the second longitudinal toothing is reduced relative to the residual longitudinal teeth such that only the longitudinal tooth reduced in radial height can be axially inserted into the obstructed tooth gap. The tooth gap is obstructed by a locking portion of the first rotary element, produced by forming or a material connection a pin resting in a bore of the first rotary element. The locking portion or the pin is arranged in the tooth gap or in axial extension to the tooth gap.

A coupling joint includes: joint member which has gear teeth; a center tube which has gear teeth meshing with the gear teeth, and through which a rotational force is transmitted between the joint member via the gear teeth and the gear teeth; a seal member which blocks a lubricated space including a meshing portion of the gear teeth and the gear teeth from the outside between the joint member and the center tube; a lubricant which fills the lubricated space; and a pressure-equalizing member which is provided to face a part of the lubricated space, changes the volume of the lubricated space by deforming in accordance with the pressure of the outside, and thereby equalizes the pressure of the lubricant and the pressure of the outside.

A coupling joint includes: joint member which has gear teeth; a center tube which has gear teeth meshing with the gear teeth, and through which a rotational force is transmitted between the joint member via the gear teeth and the gear teeth; a seal member which blocks a lubricated space including a meshing portion of the gear teeth and the gear teeth from the outside between the joint member and the center tube; a lubricant which fills the lubricated space; and a pressure-equalizing member which is provided to face a part of the lubricated space, changes the volume of the lubricated space by deforming in accordance with the pressure of the outside, and thereby equalizes the pressure of the lubricant and the pressure of the outside.

A power transmission device includes coaxially a first rotary body including a first gear on a drive source side, a second rotary body including a second gear on a driven side, a third rotary body including a third gear movably held to transmit a driving force, and a guide member disposed at one of the first gear, the second gear, and the third gear to contact a first end surface of a gear tooth of another of the first gear, the second gear, and the third gear, serving as a mating gear, to guide the first end surface between teeth of the one of the first gear, the second gear, and the third gear. The guide member extends toward the mating gear and a tip of the guide member is placed at a distance from an end of the one of the gears in the axial direction.

A gear spindle (3) obtained by inclining the axis of a spindle inner tube (10) provided at one end with an external cog inner tube gear section (40) at 0.6 degrees to 1.6 degrees with respect to the axis of a spindle outer tube (20) provided with an internal cog outer tube gear section (50) that meshes the inner tube gear section (40). On the teeth of the inner tube gear section (40) having a face width (B), a crowning of radius (Cr) is provided so that the center in the face width direction is expanded and both tooth ends are thin. The face width (B) and the crowning radius (Cr) are set within an area that is enclosed by graphs of (Cr)=1200 [mm], (Cr)=4000 [mm], (B)=0.0272(Cr)+28 [mm], (B)=59.04exp (0.0005(Cr)) [mm], and (B)=32(Cr).sup.0.274 [mm].

A gear coupling for connecting a drive shaft and an output shaft includes a first coupling portion adapted for connection to the drive shaft and a second coupling portion adapted for connection to the output shaft, Each of the first and second coupling portions has a driver toothing with an internal toothing and an external toothing in engagement with the internal toothing. An intermediate tube made of an electrically insulating material connects the first and second coupling portions with one another and electrically insulates the first and second coupling portions from one another. One of the first and second coupling portions surrounds an inner periphery of the intermediate tube and the other one of the first and second coupling portions surrounds an outer periphery of the intermediate tube.