An internal combustion engine may include an engine block, a cylinder defining at least one combustion chamber, and a piston in the cylinder. The piston may travel in a first stroke from one end to an opposite end of the cylinder, and may be sized relative to the cylinder to enable an expansion stroke portion of the first stroke while the piston travels under gas expansion pressure, and a momentum stroke portion of the first stroke for the remainder of the first stroke following the expansion stroke portion. A passageway may be formed in the piston rod to communicate gas flow between a first combustion chamber and an area external to the cylinder when the piston is in a first position, and to communicate gas flow between a second combustion chamber and an area external to the cylinder when the piston is in a second position.

An internal combustion engine may include an engine block, a cylinder defining at least one combustion chamber, and a piston in the cylinder. The piston may travel in a first stroke from one end to an opposite end of the cylinder, and may be sized relative to the cylinder to enable an expansion stroke portion of the first stroke while the piston travels under gas expansion pressure, and a momentum stroke portion of the first stroke for the remainder of the first stroke following the expansion stroke portion. A passageway may be formed in the piston rod to communicate gas flow between a first combustion chamber and an area external to the cylinder when the piston is in a first position, and to communicate gas flow between a second combustion chamber and an area external to the cylinder when the piston is in a second position.

An internal combustion engine may include an engine block, a cylinder defining at least one combustion chamber, and a piston in the cylinder. The piston may travel in a first stroke from one end to an opposite end of the cylinder, and may be sized relative to the cylinder to enable an expansion stroke portion of the first stroke while the piston travels under gas expansion pressure, and a momentum stroke portion of the first stroke for the remainder of the first stroke following the expansion stroke portion. A passageway may be formed in the piston rod to communicate gas flow between a first combustion chamber and an area external to the cylinder when the piston is in a first position, and to communicate gas flow between a second combustion chamber and an area external to the cylinder when the piston is in a second position.

An internal combustion engine may include an engine block, a cylinder defining at least one combustion chamber, and a piston in the cylinder. The piston may travel in a first stroke from one end to an opposite end of the cylinder, and may be sized relative to the cylinder to enable an expansion stroke portion of the first stroke while the piston travels under gas expansion pressure, and a momentum stroke portion of the first stroke for the remainder of the first stroke following the expansion stroke portion. A passageway may be formed in the piston rod to communicate gas flow between a first combustion chamber and an area external to the cylinder when the piston is in a first position, and to communicate gas flow between a second combustion chamber and an area external to the cylinder when the piston is in a second position.

A press for waste has an actuator (42) that moves a ram (40) in a chamber (30). The actuator and the ram are connected by a fastening system (100). The fastening system allows the ram to be displaced in a direction perpendicular to the length and direction of travel of the actuator. In this way, as inner surfaces of the chamber wear the ram may adjust to the worn surfaces without applying large forces perpendicular to the length of the actuator. When the actuator moves forward, it pushes directly against the back of the ram. When the actuator moves backwards, it pulls a pin (102) that pushes on an inner surface (108) of the ram.

A press for waste has an actuator (42) that moves a ram (40) in a chamber (30). The actuator and the ram are connected by a fastening system (100). The fastening system allows the ram to be displaced in a direction perpendicular to the length and direction of travel of the actuator. In this way, as inner surfaces of the chamber wear the ram may adjust to the worn surfaces without applying large forces perpendicular to the length of the actuator. When the actuator moves forward, it pushes directly against the back of the ram. When the actuator moves backwards, it pulls a pin (102) that pushes on an inner surface (108) of the ram.

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.

A hydraulic fluid cylinder is equipped with a cylinder tube, a piston unit, and a piston rod. The piston unit has a gasket and a piston body comprising a plurality of members and provided with a gasket-mounting groove. The piston body has a first piston member which projects to the outside from the piston rod, and also has a second piston member positioned so as to be adjacent to the first piston member. The gasket-mounting groove is formed from a combination of at least two members.

Provided is a plunger including: a plunger body; a first surface configured to come into contact with an inner peripheral surface of the cylindrical member; a second surface disposed on a base end side relative to the first surface, the second surface having an outer diameter that is smaller than that of the first surface; an outer stepped surface disposed between the first surface and the second surface; a first housing disposed in an area at least partly corresponding to the second surface in the recess, the first housing being provided for housing a tip part of the pin; a second housing disposed on the base end side relative to the first housing, the second housing having an inner diameter that is smaller than a largest inner diameter of the first housing; and an inner stepped surface disposed between the first housing and the second housing.