A camshaft is equipped with an inner shaft which is arranged rotatably inside a cylindrical outer shaft. Further, in the inner shaft, a plurality of pin holes extend along diametrical directions thereof, and are disposed at intervals along the axial direction of the inner shaft. The directions in which adjacent pin holes extend are arranged at angles obtained by dividing 360 degrees by the number of cylinders. The inner shaft and the inner cams are fixed in a state in which large diameter portions of pins, each of which is provided with a small diameter portion and a large diameter portion, are press-fitted through insertion holes of the inner cams and notches of the outer shaft, and are press-fitted into the pin holes.

Provided is a heat treatment method for a cam piece, and the cam piece has an insertion hole into which a cam shaft is inserted, a base portion configuring a base circle of a cam, and a nose portion configuring a cam ridge. The heat treatment method for the cam piece includes: a first step of using a jig formed into a shape having a cavity, the jig being inserted into the insertion hole such that the cavity is located between an inner circumferential surface of the nose portion of the cam piece and a central axis of the jig; and a second step of heating the cam piece from an outer circumferential surface side by high-frequency induction heating in a state in which the jig is inserted in the insertion hole of the cam piece.

A four-stroke opposed piston engine contains a drive train containing two outer crank shaft gears, and two inner synchro gears, wherein the inner synchro gears are twice the diameter of the outer crank shaft gears. Additionally, novel piston faces are presented that when fixed on opposed pistons, create annular cavities that form advantageous combustion chambers when the pistons are at top dead center.

A valve drive may include a sliding cam element that is held on a carrier shaft so as to be axially displaceable along an axis of rotation of the carrier shaft. The sliding cam element may include at least one cam profile group with cam profile sections of mutually different form. The valve drive may further include a pick-off element by way of which a control movement can be picked off from the cam profile sections and transmitted to a valve. The sliding cam element may also include a second cam profile group that is similar or identical to the first cam profile group and, which for the joint control of one valve, may interact with the pick-off element.

Provided is a heat treatment method for a cam piece, and the cam piece has an insertion hole into which a cam shaft is inserted, a base portion configuring a base circle of a cam, and a nose portion configuring a cam ridge. The heat treatment method for the cam piece includes: a first step of using a jig formed into a shape having a cavity, the jig being inserted into the insertion hole such that the cavity is located between an inner circumferential surface of the nose portion of the cam piece and a central axis of the jig; and a second step of heating the cam piece from an outer circumferential surface side by high-frequency induction heating in a state in which the jig is inserted in the insertion hole of the cam piece.

A sliding cam system is provided including: at least one sliding cam arranged in a fixed, but axially slideable manner on at least one axially fixed base shaft for forming a cam shaft of a reciprocating internal combustion engine; at least one actuator device for adjusting the sliding cam into different axial positions using at least one actuator pin that can engage in at least one sliding groove on a circumference of the sliding cam, wherein the actuator device has a housing attached to the engine and the sliding grooves are arranged in a groove section of the sliding cam; and a bracket encompassing the groove section using side shoulders, directed parallel to a longitudinal axis of the base shaft and provided with an opening in a region of the actuator pins, wherein the sliding cam has at least two sliding grooves having at least partially different depths, wherein the bracket is directed in the actuator device and wherein a positive-fit depth stop device is provided between the bracket and the actuator pin(s).

A camshaft is equipped with an inner shaft which is arranged rotatably inside a cylindrical outer shaft. Further, in the inner shaft, a plurality of pin holes extend along diametrical directions thereof, and are disposed at intervals along the axial direction of the inner shaft. The directions in which adjacent pin holes extend are arranged at angles obtained by dividing 360 degrees by the number of cylinders. The inner shaft and the inner cams are fixed in a state in which large diameter portions of pins, each of which is provided with a small diameter portion and a large diameter portion, are press-fitted through insertion holes of the inner cams and notches of the outer shaft, and are press-fitted into the pin holes.

A compact power unit with a sufficient clearance between a stud bolt and a fixing shaft of a cam chain tensioner pivot mechanism for supporting a cam chain tensioner guide. The power unit including a crankshaft, a stud bolt configured to fix a crankcase and a cylinder body to each other, a cam chain, a cam chain tensioner mechanism including a cam chain tensioner guide, and a cam chain tensioner pivot mechanism including a pivot plate, a fixing shaft, and a swinging shaft, the fixing shaft and the swinging shaft are arranged so as to straddle the axis of the stud bolt as viewed in the axial direction of the crankshaft.

A sliding cam system is provided including: at least one sliding cam arranged in a fixed, but axially slideable manner on at least one axially fixed base shaft for forming a cam shaft of a reciprocating internal combustion engine; at least one actuator device for adjusting the sliding cam into different axial positions using at least one actuator pin that can engage in at least one sliding groove on a circumference of the sliding cam, wherein the actuator device has a housing attached to the engine and the sliding grooves are arranged in a groove section of the sliding cam; and a bracket encompassing the groove section using side shoulders, directed parallel to a longitudinal axis of the base shaft and provided with an opening in a region of the actuator pins, wherein the sliding cam has at least two sliding grooves having at least partially different depths, wherein the bracket is directed in the actuator device and wherein a positive-fit depth stop device is provided between the bracket and the actuator pin(s).

A valve drive may include a sliding cam element that is held on a carrier shaft so as to be axially displaceable along an axis of rotation of the carrier shaft. The sliding cam element may include at least one cam profile group with cam profile sections of mutually different form. The valve drive may further include a pick-off element by way of which a control movement can be picked off from the cam profile sections and transmitted to a valve. The sliding cam element may also include a second cam profile group that is similar or identical to the first cam profile group and, which for the joint control of one valve, may interact with the pick-off element.