A piston includes a piston cap and a piston rod with the piston cap being removable from the piston rod body. The piston cap includes a cap body and a socket extending into the cap body. A mounting portion of the piston rod body extends into the socket of the cap body to connect the piston rod body to the piston cap. A wear sleeve is mounted on the piston rod.

A piston assembly includes a piston head for reciprocating back and forth within a cylinder of an engine, an upper rod coupled to the piston head at one longitudinal end of the upper rod and fixed relative to the piston head, and a lower rod rotatably coupled to an opposite longitudinal end of the upper rod, the lower rod configured to pivot about the opposite longitudinal end of the upper rod. The lower rod is configured to couple to a crankshaft at a longitudinal end of the lower rod opposite the upper rod. Methods of forming a piston assembly and engines incorporating such piston assemblies are also disclosed.

A reciprocating saw includes a housing, a motor, and a drive mechanism. The drive mechanism includes a driven gear that is rotated by the motor. The driven gear is vertically-oriented within the housing. The drive mechanism also includes a drive arm coupled to the driven gear to translate rotary motion of the driven gear into reciprocating motion, and an output shaft coupled to the drive arm to reciprocate relative to the housing along a spindle axis through a cutting stroke and a return stroke. The drive mechanism further includes a counterweight coupled to the driven gear and rotating with the driven gear through a path and in a same direction. As the counterweight moves through a rearward half of the path, the counterweight generally moves in an upward direction, and as the counterweight moves through a forward half of the path, the counterweight generally moves in a downward direction.

A reciprocating saw includes a housing, a motor, and a drive mechanism. The drive mechanism includes a driven gear that is rotated by the motor. The driven gear is vertically-oriented within the housing. The drive mechanism also includes a drive arm coupled to the driven gear to translate rotary motion of the driven gear into reciprocating motion, and an output shaft coupled to the drive arm to reciprocate relative to the housing along a spindle axis through a cutting stroke and a return stroke. The drive mechanism further includes a counterweight coupled to the driven gear and rotating with the driven gear through a path and in a same direction. As the counterweight moves through a rearward half of the path, the counterweight generally moves in an upward direction, and as the counterweight moves through a forward half of the path, the counterweight generally moves in a downward direction.

A crank mechanism for the use in an in-line boxer engine has at least two diametrically opposed cylinders, that has a crankshaft and the respective pistons as well as connecting rods for each cylinder of the in-line boxer engine, with the connecting rods cooperatively connecting the pistons with the crankshaft. Each of the connecting rods encompasses a respective piston connecting portion, at one end having bushings accepting a gudgeon pin. At the other end, the central connecting rod has a one-piece crankshaft bearing portion for the crankpin whereas the forked connecting rod has a crankshaft bearing portion with two spaced limbs resultant in bifurcated crankshaft bearing portions for the crankpin. The crankshaft possesses a cylindrical central middle crankpin, that is eccentric towards the crankshaft, onto which a cylindrical outer crank pin is immediately attached at each side without crank webs.

A connecting rod assembly has a connecting rod with a large end and a small end, a piston wrist pin, and fasteners to connect the connecting rod to the piston wrist pin and optionally one or more shims in between the connecting rod and piston wrist pin. A notch on the wrist pin allows for the seating of a flat surface on the small end of the connecting rod in the connecting rod assembly. Side walls on both the notch and the small end of the connecting rod limit twist. The connecting rod assembly allows for the adjustment of piston location in a cylinder while limiting connecting rod twist.

A connecting rod assembly has a connecting rod with a large end and a small end, a piston wrist pin, and fasteners to connect the connecting rod to the piston wrist pin and optionally one or more shims in between the connecting rod and piston wrist pin. A notch on the wrist pin allows for the seating of a flat surface on the small end of the connecting rod in the connecting rod assembly. Side walls on both the notch and the small end of the connecting rod limit twist. The connecting rod assembly allows for the adjustment of piston location in a cylinder while limiting connecting rod twist.

An internal combustion may include a cylinder having a first combustion chamber at one end and a second combustion chamber at an opposing end, first and second cylinder heads located at an end of the first and second combustion chambers, respectively, and a double-faced piston slidably mounted therein. The piston may be configured to move in a first stroke that includes an expansion stroke portion and a non-expansion stroke portion. The engine may further include first and second piston rod portions extending from opposite faces of the piston. A recess in the piston rod portions may be configured to communicate gases between a combustion chamber and locations outside the cylinder. There may also be a chamber surrounding the first or second piston rod portion, the chamber configured to be supplied with gas and the chamber being isolated from the first combustion chamber and the second combustion chamber.

An internal combustion may include a cylinder having a first combustion chamber at one end and a second combustion chamber at an opposing end, first and second cylinder heads located at an end of the first and second combustion chambers, respectively, and a double-faced piston slidably mounted therein. The piston may be configured to move in a first stroke that includes an expansion stroke portion and a non-expansion stroke portion. The engine may further include first and second piston rod portions extending from opposite faces of the piston. A recess in the piston rod portions may be configured to communicate gases between a combustion chamber and locations outside the cylinder. There may also be a chamber surrounding the first or second piston rod portion, the chamber configured to be supplied with gas and the chamber being isolated from the first combustion chamber and the second combustion chamber.

The cylinder rod of a hydraulic cylinder includes a body portion having a bar shape, and a head portion arranged at a longitudinal end of the body portion. The body portion has a coating formed on its outer peripheral surface. The coating includes, in terms of area ratio in cross section, not less than 56.1% and not more than 84.4% of a chromium carbide phase, with the remainder consisting of a nickel-based alloy phase and an oxide phase. The area ratio of the chromium carbide phase may be 61.7% or more.