Abstract: A gear shift device is used in a transmission of an engine, and includes: a shift drum that changes a speed change stage of the transmission according to a rotational position about an axis; an actuator having a driving shaft substantially orthogonal to this shift drum; a worm shaped barrel cam that is arranged parallel to the driving shaft of this actuator and that has a cam groove on an outer circumference; and a wheel gear that is coaxially fixed on the shift drum and that has a plurality of pins on an outer circumference. At least a pair of each pin of the wheel gear and the cam groove of the barrel cam is engaged with each other, and the shift drum is rotated by the actuator via the barrel cam and the wheel gear, to thereby change the speed change stage of the transmission.

Abstract: A transmission in which two gears can be selected at the same time is provided without the need to greatly increase the size of the transmission. The transmission comprises a plurality of gear change members arranged for moving in a predetermined shifting direction to select a gear, and a shift operating member which is capable of moving in a selecting direction through notches formed in the gear change members. The shift operating member has an engaging portion capable of engaging with one of the gear change members via the corresponding notch to move the gear change member in the shifting direction. A gap between adjacent gear change members in the selecting direction is larger than a thickness of the engaging portion in the selecting direction.

Abstract: An operating device for a manual transmission apparatus includes: a plurality of operation shafts, supported at a housing to move in an axial direction thereof and selectively engaging one of a plurality of shift gear sets by one of the plurality of the operation shafts being moved in the axial direction thereof; a shift-and-select shaft, supported at the housing, selecting one of the plurality of the operation shafts by rotating in a circumferential direction of the shift-and-select shaft and moving the selected operation shaft in the axial direction of the selected operation shaft by moving in the axial direction of the shift-and-select shaft; an operating portion for manually operating the shift-and-select shaft; and an inertia unit, including an engagement portion, which is engageable with the shift-and-select shaft, pivotably supported at the housing, and pivoting in response to a movement of the shift-and-select shaft in the axial direction thereof.

Abstract: An operating device for a manual transmission apparatus, comprising a plurality of operation shafts, a shift-and-select shaft having an engagement groove extending in a circumferential direction thereof, selecting one of a plurality of operation shafts by rotating and moving the selected operation shaft in an axial direction thereof by moving in an axial direction of the shift-and-select shaft, an operating portion for manually operating the shift-and-select shaft, an inertia unit including an engagement pin, positioned within the engagement groove and pivoting in response to a movement of the shift-and-select shaft in the axial direction thereof, and a swing-and-contact member provided at the engagement pin of the inertia unit so as to swing when being pressed by one of first and second inner surfaces of the engagement groove in accordance with the movement of the shift-and-select shaft and contacting the first and second inner surfaces of the engagement groove.

Abstract: A transmission, includes: a shift member, adapted to be moved in a shifting direction and a selecting direction; a plurality of shift lugs, each of which has a pair of first claw portions spaced apart from each other in the shifting direction, and which are arranged in the selecting direction; and a plurality of shift forks, connected to the shift lugs via shift rails.

Abstract: A transmission has a movable transmission part movably connected to a fixed transmission part via a shaft to undergo pivotal movement relative to the fixed transmission part about an axis of the shaft. Each of the transmission parts has a hollow cylindrical connecting portion through which the shaft extends. One of the connecting portion of the movable transmission part and the connecting portion of the fixed transmission part is received in the other of the connecting portions with a single seal member disposed therebetween so that an internal space of the fixed transmission part and an internal space of the movable transmission part communicate with each other to thereby form a single hermetically-sealed space for holding therein a lubricating oil.

Abstract: An internal shift control mechanism is provided for a motor vehicle gearbox that includes, but is not limited to a fork member for engaging and displacing a synchronizer sleeve of the gearbox in an axial direction between a neutral position and at least one active position, a carriage supporting the fork member , displaceably guided in the axial direction, a shifter axle having an axis of rotation which extends transversally with respect to the displacement direction of the carriage and carrying a shift arm which engages a shift gate formed on the carriage . In the active position a tangent at a contact point between the shift arm and the shift gate is perpendicular to a radius extending from the axis to the contact point.

Abstract: A transmission, includes: a plurality of shift members, adapted to be moved in a shifting direction and a selecting direction; a shift lug, having a pair of claw portions spaced apart from each other in the shifting direction; and a shift fork, connected to the shift lug via a shift rail. The shift members are moved by an actuator so that one of the shift members pushes one of the claw portions in the shifting direction to thereby selectively move the shift lug in the shifting direction so as to cause the shift fork to perform a gear shift operation via the shift rail. The shift members are disposed as to be offset from each other in the shifting direction.

Abstract: A transmission unit for a motor vehicle is provided with a fixed supporting structure, a driving transmission shaft and at least one driven transmission shaft that are parallel to one another, and a control device, which has a control member that is movable with respect to the supporting structure; the control member is able to translate along a control axis between a plurality of operating positions, each associated to a corresponding range of gears, and to turn, in each operating position, about the control axis between an idle angular position and at least one engagement angular position, in which it controls engagement of a gear forming part of the range selected; the control member is set at least in part in front of an axial end of the transmission shafts.

Abstract: A gear-shifting device for a manual transmission, in which the operational force applied at the change-lever L in the shift operation is transmitted selectively to actuate a synchro-sleeve for a gear shift, comprises a shift arm 53, which is rotatable in correspondence to the shift operation of the change-lever L, and a 1st-2nd speed shift piece 41, which is in contact with the shift arm 53 and is capable of shifting in response to the rotation of the shift arm 53. In the gear-shifting device, the shift arm 53 has heteromorphous cams at its contacting part, which is in contact with the 1st-2nd speed shift piece 41, and the heteromorphous cams are designed in a compound arc figure, which comprises a plurality of combined arcs having different curvature radii.

Abstract: A multi-gear-speed transmission includes cam rods in sliding contact with an inner peripheral surface of an inner cavity of a gear shaft; pin members inserted in pin holes bored in the gear shaft in the radial directions and which are advanced or retreated by alternatedly making contact with the sliding contact surfaces of the cam rods and cam grooves. Swing claw members are rotatably supported on pivot pins provided in the gear shaft and which are advanced or retracted by the pin members to be engaged with or disengaged from gears (n). The swing claw members and the pivot pins are embedded in recessed parts formed in the outer periphery of the gear shaft, annular bearing collar members externally fitted over the gear shaft are arranged to press the pivot pins from the outer side, and the gears (n) are rotatably borne on the bearing collar members.

Abstract: A shift drive device with a shift arm having one end secured to a shift spindle with a guide hole for receiving a pin, provide to project therefrom, inserted therethrough and engaged therewith. A turn-restriction hole receives a restriction pin provided on a transmission case. A space that is needed for turning the shift arm is reduced. A turn-restriction hole is provided in a shift arm so as to be disposed on a straight line connecting an axial line of a shift spindle with the center of a guide hole.

Abstract: A shift device for a speed change transmission in motor vehicles having at least one selector rod which is movably supported in the gear housing in cross walls, by means of which rod the transmission steps in the gear housing can be shifted. The selector rod on one end penetrates a cross wall of the transmission, which wall separates the oil compartment, and by means of a plastic sleeve, which is sprayed onto the selector rod, is guided and sealed in the corresponding through hole of the cross wall of the transmission.

Abstract: A gear selector assembly includes a selector shaft, an internal mode switch mounted on the selector shaft, and a detent lever mounted on the selector shaft and rotatable with the selector shaft. The detent lever is indexed relative to the internal mode switch. A spring assembly is in engagement with the detent lever. The spring assembly has a first member that engages the internal mode switch to prevent the internal mode switch from rotating and has a second member that engages the internal mode switch to prevent the internal mode switch from rotating if the first member does not engage the internal mode switch.

Abstract: A transmission parking lock and an actuating element (1) for the parking lock. The actuating element includes a pull rod (2) and a roller carrier (3) on which are arranged a first roller (13) for rolling on a first rolling surface on the pawl of the parking lock and a second roller (14) for rolling on a second rolling surface on a guide element, such that the roller carrier (3) can be moved along a predetermined path in the longitudinal direction of the pull rod (2). The roller carrier (3) can move longitudinally on the pull rod (2).

Abstract: A shifting device including at least one shifting element secured axially on the shaft longitudinally in at least one direction of extension of the longitudinal axis of the shaft by a bearing element on the shaft. The shifting element has transversely projecting fingers.

Abstract: A driving force interrupting mechanism for interrupting a driving force to a driving shaft. The mechanism includes a spindle rotatably attached to a first housing body for supporting the driving shaft so that the driving shaft can be rotated, a fork attached to the spindle so that the fork can be swung, and a lost motion mechanism that renders further rotation of the spindle to be ineffective in swinging the fork when the spindle is rotated and the fork is swung to a predetermined position in which an input shaft and an output shaft are coupled is provided on the spindle. The resulting configuration is compact and cost effective.

Abstract: An adjustable linkage comprises a housing, a slider slidable within the housing, and a locking member seated within an opening in the housing and selectively contacting the slider to prevent sliding movement thereof. The adjustable linkage is attached between a first attachment point and a second attachment point to automatically adjust a linkage length. Preferably, the adjustable linkage is used within a vehicle as a link between an automatic vehicle transmission and a vehicle shifter, with the design allowing ease of installation within the vehicle.

Abstract: A selector fork arrangement for a manual transmission in a motor vehicle is suggested that largely comprises a fork body (1) and carrying element (2,3) that connect the fork body (1) to the control rod (9). Fork body (1) and carrying elements (2, 3) are cut entirely from flat metal and are riveted to one another by means of rivet projections (7, 8, 15), which are themselves formed from the flat metal, and complementary rivet openings in the carrying elements (2, 3). This selector fork arrangement satisfies all requirements in terms of strength and functionality, can be produced and assembled in a simple manner, and does not require any adjustment or finishing processes after assembly and prior to installation in the manual transmission.

Abstract: A shift operating apparatus includes a shift and select shaft moved in an axial direction upon a shift operation and rotated about an axis upon a select operation, an inner lever provided at the shift and select shaft, the inner lever being moved in the axial direction upon the shift operation and being rotatable about the axis upon the select operation, a plurality of shift fork heads arranged about the axis along a circumferential direction of the shift and select shaft; and plural shift grooves formed at the inner lever to be open in the circumferential direction of the shift and select shaft. The plural shift grooves are arranged along the axial direction with an interval relative to an adjacent shift groove of each other, the interval which corresponds to an amount of a shift stroke.

Abstract: A manually controlled shifting conversion apparatus for a multistage transmission having multiple shifting packets wherein gears for successive, non-adjacent gear ratios are located in each shifting packet and gears for successive, adjacent gear ratios are located in different shifting packets. The gears located in each shifting packet are respectively engaged by opposing axial displacements of the shifting packet controlled by a gear shift lever (4). The gear shift level (4) has a shifting pattern wherein the shifting positions of successive gear ratios are located in opposing positions in the shifting pattern.

Abstract: A shifting device for a change-speed transmission, in particular for a motor vehicle, having a shifting gate which has at least one recess, and having a first guide pin which is arranged in such a manner that it engages in the recess of the shifting gate in order to prevent a simultaneous engagement of two speeds of the change-speed transmission, wherein a second guide pin is arranged at a distance from the first guide pin, and in that the shifting gate on the one hand and the guide pins on the other hand can be moved relative to each other in order to change over between different speeds of the change-speed transmission.

Abstract: A stopper structure of a shift lever, which is pivotally movably supported and adapted to a shift operation apparatus for changing shift stages of a transmission by an operation of the shift lever, includes a protruding portion and a plurality of recessed portions. The protruding portion is formed at an outer peripheral portion of the shift lever. The plurality of recessed portions is formed at a member being stationary relative to the shift lever. Further, the plurality of recessed portions is formed to correspond to a shifting pattern and to be selectively and releaseably fitted by the protruding portion when the shift lever is shifted to a predetermined shift position.

Abstract: An adjusting device for a transmission, such as a motor vehicle transmission is described. The transmission has at least one moveable adjusting element, at least two sensors for detecting a position of the at least one moveable adjusting element, and a code path of the at least one moveable adjusting element having sections of different heights which are provided to be scanned by the at least two sensors, the sections of the code path of different heights being arranged at least two-dimensionally. The at least two sensors are arranged parallel to one another.

Abstract: A gear-shifting device 50 for a manual transmission comprises a shift arm 53, which is rotatable in correspondence to the shift operation of a change-lever L, and shift pieces 41, 43 and 45, each of which shifts in correspondence to the rotation of the shift arm 53, with this shifting of the shift piece 41 achieving a gear shift. The gear-shifting device 50 further comprises a load-attenuating mechanism 90, which includes a spline groove 51b, a fitting room 91, a steel ball 92 and a coned spring 93. In the attenuating mechanism, the steel ball 92 is pushed to the spline groove 51b by the coned spring 93, allowing the shift arm 53 to rotate with respect to the shift selector shaft 51 to reduce the load acting on the change-lever L from synchro-sleeves 71, 73 and 75.

Abstract: A shift device for a transmission, which comprises a sliding sleeve, a shift fork engaging in the sliding sleeve, and an actuator that can rotate on a shaft that is disposed at an angle to the transmission shaft. In order to provide a simple and reliable control that satisfies all functional requirements, a cam having two flanks and a flattened section on the maximum radius is disposed on the shaft. On the base of the shift fork, two interacting pushrods are disposed at a fixed distance so that one pushrod rests against the one flank and the other pushrod rests against the other flank and one pushrod rests against the flattened section in at least one extreme position.

Abstract: A check mechanism for a shift lever apparatus includes: a base bracket formed with press-fit holes and locked parts; a shift lever swingably supported by the base bracket; a check member being supported by the shift lever, the check member moving in response to a swing of the shift lever; a check block attached to the base bracket and formed with a check groove; press-fit protrusions provided in the check block being pressed fit into the press-fit holes and having a plurality of ribs on its cylindrical outer periphery; and locking claw parts which being provided in the check block, the locking claw parts being locked to the locked parts formed in the base bracket in a state that the press-fit protrusions being completely pressed fit into the corresponding press-fit holes.

Abstract: A gearbox actuator comprising a selector shaft 2 which is arranged in a housing and is driven by a drive. A shift finger 3 and disengaging shaped elements 4 used to actuate gearshift rails are arranged on the selector shaft, and jibs for 12-15 supporting and guiding the gearshift rails are arranged on the housing. The gearbox actuator 1 comprises the central selector shaft 2 mounted in bearing elements 19 and comprises a shift finger 3 and two disengaging shaped elements 4 arranged in the center thereof, at a distance corresponding to the width of a channel. Preferably, the selector shaft 2 is driven by a brushless motor 5 by means of a double planetary stage 6 and a toothed segment 7 which engages a toothed wheel 16 that is preferably positioned in a housing element 17. A preferably second brushless motor 8 drives a sliding element 37 by means of spindle 9, the sliding element displacing the shift finger 3 and the disengaging shaped elements 4 on the selector shaft 2.

Abstract: A device and a method for determining the position of a gear shift element 1 in a claw clutch operated automated gear box of a vehicle. The gear shift element 1 has gear teeth that correspond to at least two gear wheels 5, 8 which have a different axial extension on both sides of a groove 9. The position of the gear shift element 1 can be determined by way of the method according to the invention.

Abstract: Traction planets and traction rings can be operationally coupled to a planetary gearset to provide a continuously variable transmission (CVT). The CVT can be used in a bicycle. In one embodiment, the CVT is mounted on the frame of the bicycle at a location forward of the rear wheel hub of the bicycle. In one embodiment, the CVT is mounted on and supported by members of the bicycle frame such that the CVT is coaxial with the crankshaft of the bicycle. The crankshaft is configured to drive elements of the planetary gearset, which are configured to operationally drive the traction rings and the traction planets. Inventive component and subassemblies for such a CVT are disclosed. A shifting mechanism includes a plurality of pivot arms arranged to pivot about the centers of the traction planets as a shift pin hub moves axially.

Abstract: A transmission is provided for changing gears by performing rotation control of a shift drum transmission between an internal combustion engine and a drive wheel by use of an actuator provided on one side of the shift drum and an intermittent feed mechanism driven by the actuator disposed on the other side of the shift drum.

Abstract: A shifting device for a transmission, in which at least one gearshift package is allocated to two non-successive gears and each of these gearshift packages is coupled with a gearshift lever. An H- or a multiple H-shifting diagram is allocated to the gearshift lever, in which the gears that can be selected within a gearshift path are allocated to different gearshift packages. The gearshift lever and the gearshift packages are connected to a conversion device with which a gearshift lever movement to take out a previous gear in a gearshift path causes this gear to be taken out in a first gearshift package. A gearshift lever movement for putting in the new gear in the same gearshift path, a second gearshift package puts in this new gear. The conversion device functions in such a way that the gearshift lever is coupled with an axially displaceable and radially pivotable shift finger shaft.

Abstract: A gear-changing device for a motor-vehicle gearbox, including a gear-changing lever which is pivotable arranged with respect to a support part about a bolt. The bolt is held in an axially nondisplaceable manner with respect to the support part. In order to provide a cost-effective and easy-to-install gear-changing device, the bolt is held by a catch.

Abstract: The invention relates to a gear shifting device (2) comprising a single-rod gear shifting system in a housing of a motor vehicle manual gearbox. Said device comprises a central gearshift shaft (32) and fork-type gear shifting elements in the form of gear shifting swinging forks or gear shifting forks (4, 6, 8, 10) which are optionally and individually engaged with the gearshift shaft (32) by rotating the same (32), and which carry out a gear shift of the selected gear shifting element by means of displacement of the gearshift shaft (32) along a rotational axis (34) of said gearshift shaft (32). Said gear shifting device (2) comprises a first element (58, 60) which is connected to the gearshift shaft (32) and which co-operates with a second element (62) fixed in the housing, in order to define the rotation of the gearshift shaft (32).

Abstract: An oil supplying device (34, 36, 38) for a vehicle transmission (2) having one transmission housing (4, 6) with gears (10, 12, 16, 18, 22) situated upon shafts (8, 14, 20) and having teeth, bearings in which gears (10, 12, 16, 18, 22) and shafts (8, 14, 20) are rotatably mounted and one switch gear (30, 32, 50) suited to connect the gears (10, 12, 16, 18, 22) and shafts (8, 14, 20) for a transmission of torque. The device has an oil collecting duct (34) arranged on movable elements (32, 50) of the switch gear (30, 32, 50) which moves with the elements (32, 50) of the switch gear (30, 32, 50) and which extends substantially through the part in the transmission housing (4, 6) having all the gears (10, 12, 16, 18, 22). The oil collecting duct (34) has at least one opening (36, 38) which during movements of the elements (32, 50) of the switch gear (30, 32, 50) coats areas within the transmission housing (4, 6) on which the bearings and teeth are situated.

Abstract: A differential transmission apparatus. The differential transmission apparatus includes a base, a fixed gear, a rotating member, an output shaft, a reduction gear, an acceleration gear, a shifting device, at least one transmission shaft, at least one first gear, at least one second gear, and at least one third gear. The fixed gear is fixed on the base. The rotating member is adjacent to the fixed gear. The output shaft rotatably fits in the rotating member, fixed gear, and base. The reduction gear is slidably disposed on the output shaft. The acceleration gear is slidably disposed on the output shaft and connected to the reduction gear. The shifting device is disposed on the base and output shaft. The first, second, and third gears are fixed on the transmission shaft and the third gear is between the second gear and the rotating member.

Abstract: A gearshift device for a multiple-gear change box of a vehicle includes at least two gearshift rods with a rectangular cross-section. A roller bearing and a locking device are provided for guiding and locking the gearshift rods, with each gearshift rod having its own locking element.

Abstract: A plurality of shift rails are manipulated by a manual control rod to selectively actuate one or more synchronizer mechanisms. The control rod is moved angularly and linearly during ratio selection. Each synchronizer mechanism may control two or more drive ratios in a planetary transmission. At least two of the rails are interconnected by a reversing mechanism to permit consistent movement of the rails regardless of the direction of movement of the control rod.

Abstract: A boot assembly for a vehicle includes a retainer adapted to be connected to vehicle structure of a vehicle and a boot for surrounding either one of a shifter and parkbrake of the vehicle. The boot assembly also includes a seal connected to the boot and to the retainer to prevent the boot from exiting the retainer.

Abstract: An actuator for an automated transmission in a motor vehicle drive train has a central actuating shaft with a shift finger. Two sleeves are supported concentrically on the actuating shaft and can be driven in mutually independent rotation. Two grooves of opposite helical pitch are arranged on the actuating shaft, and each of the sleeves has at least one inward-directed guide pin engaging one of the grooves.

Abstract: A shift lever apparatus is provided in which, after a slider has been assembled at a case, a link is assembled to the case while an intrusion shaft is inserted into a hole. For assembly of the link to the case, an assembly pawl provided at the link is resiliently deformed and inserted at an assembly portion which is provided at into the case. The assembly pawl includes an engaging protrusion that is engaged with a surrounding area of the assembly portion by resilient force of the assembly pawl. A blocking member is pre-positioned to interfere with the assembly pawl when the engaging protrusion is engaged with the surrounding area to block release of the assembly pawl.

Abstract: A machine tool, particularly a hand machine tool, including an indexing mechanism which is switchable by an actuating element via at least one coupling element, and including at least one spring element arranged in the flux of force between the actuating element and the coupling element. The spring element in the flux of force from the actuating element in the direction of the coupling element is fixedly connected to a first component in at least two actuating directions, and in the opposite direction of the flux of force, is fixedly connected to a second component at least in the two actuating directions.

Abstract: A shift assembly for a transfer cases, manual and semi-automatic transmissions comprises a drive motor having a worm gear output which engages and drives a gear having an eccentric drive pin disposed parallel to and offset from the axis of a rotation of the gear. The drive pin engages a slot in a shift fork which extends normal to the axis of movement of the shift fork and associated speed change or gear shift mechanism. The shift fork is disposed upon and supported by a shift rail. Uni-directional or bi-directional rotation of the drive motor rotates the gear and sequentially moves the eccentric pin, shift fork and shift mechanism between first and second terminal positions and, typically, a center or intermediate, neutral position.

Abstract: A locking device is provided with a locking finger (12), the locking finger (12) being provided with a clearance space (12a).

Abstract: A gear shift mechanism has a displacement device, which can be operated by an actuator, for the axial displacing of a sliding sleeve. The actuator is connected with the displacement device by way of at least one joint. Such an articulated connection between the actuator and the displacement device permits a greater freedom with respect to the spatial arrangement of the actuator and thus a very compact construction.

Abstract: In a control mechanism with a switchable transmission path comprised of mechanism links mounted on a frame, and with a switching pinion gear, through which at least two mechanism links can be optionally incorporated in the transmission path for switching purposes, wherein the two mechanism links are moveably held on a mount of the frame via switching elements, and wherein the switching pinion gear acts through a switching path to select and/or engage or disengage one of the two mechanism links on the switching elements, the mount can encompass a bearing element that is arranged so that it can move relative to the frame, and comprises part of the switching path, and an insertion lockout can be securely fastened to the frame, and the switching elements can be secured to the mount by means of an axially divided bearing block.

Abstract: A bearing arrangement (2) in a manual transmission for transferring torque between at least a first guide surface (14b) on a swivel element (14), which can swivel and which is fixed along the bearing relative to the manual transmission, and a second flat guide surface (19a), which can move in the longitudinal direction relative to the bearing (2) and which is supported with the swivel element (14) so that it can swivel at least in the bearing (2). The bearing holds a selector shaft (4) so that it can move in the longitudinal direction and so that it can also swivel, wherein the selector shaft (4) is provided with an adapter (19).

Abstract: The invention relates to a gear shifting device (2) comprising a single-rod gear shifting system in a housing of a motor vehicle manual gearbox. Said device comprises a central gearshift shaft (32) and fork-type gear shifting elements in the form of gear shifting swinging forks or gear shifting forks (4, 6, 8, 10) which are optionally and individually engaged with the gearshift shaft (32) by rotating the same (32), and which carry out a gear shift of the selected gear shifting element by means of displacement of the gearshift shaft (32) along a rotational axis (34) of said gearshift shaft (32). Said gear shifting device (2) comprises a first element (58, 60) which is connected to the gearshift shaft (32) and which co-operates with a second element (62) fixed in the housing, in order to define the rotation of the gearshift shaft (32).

Abstract: A gear change device comprising a select actuator for operating a shift lever in a direction of selection and a shift actuator for operating the shift lever in a direction of shift, wherein the select actuator comprises a casing, a shift lever support member that is disposed in the casing so as to slide in an axial direction and supports the shift lever, a magnetic moving means disposed on the outer periphery of the shift lever support member, a cylindrical fixed yoke surrounding the magnetic moving means, and a coil disposed on the inside of the fixed yoke.

Abstract: A modular unit of a gear-shifting mechanism with individual assembled together components including a machine part and a support therefor, which are rotatable relatively. The unit is subjected after the assembly of the components to a complete heat treatment and optionally subsequently to a coating. The heat treatment may be thermochemical or nitriding and the coating layer may be iron oxide.