A piston rod unit and a method for producing a piston rod unit, or a shaft, in light-weight construction, with a rod which is hollowly-drilled by means of a deep bore into the rod shank, and the resulting rod opening is closed subsequently by means of a forging process.

A piston rod unit and a method for producing a piston rod unit, or a shaft, in light-weight construction, with a rod which is hollowly-drilled by means of a deep bore into the rod shank, and the resulting rod opening is closed subsequently by means of a forging process.

An annular seal for sealing an opening in a pump housing surrounding a piston rod includes a primary sealing portion with an inner surface adjacent to the piston rod and an outer surface adjacent to the pump housing. An initial sealing portion features an inner wall and an outer wall so that an annular space is defined therebetween. A top wall extends between the inner and outer walls. A coil spring is positioned within the annular space of the initial sealing portion and urges the inner wall into engagement with the piston rod and the outer wall into engagement with the pump housing.

An annular seal for sealing an opening in a pump housing surrounding a piston rod includes a primary sealing portion with an inner surface adjacent to the piston rod and an outer surface adjacent to the pump housing. An initial sealing portion features an inner wall and an outer wall so that an annular space is defined therebetween. A top wall extends between the inner and outer walls. A coil spring is positioned within the annular space of the initial sealing portion and urges the inner wall into engagement with the piston rod and the outer wall into engagement with the pump housing.

An annular seal for sealing an opening in a pump housing surrounding a piston rod includes a primary sealing portion with an inner surface adjacent to the piston rod and an outer surface adjacent to the pump housing. An initial sealing portion features an inner wall and an outer wall so that an annular space is defined therebetween. A top wall extends between the inner and outer walls. A coil spring is positioned within the annular space of the initial sealing portion and urges the inner wall into engagement with the piston rod and the outer wall into engagement with the pump housing.

An annular seal for sealing an opening in a pump housing surrounding a piston rod includes a primary sealing portion with an inner surface adjacent to the piston rod and an outer surface adjacent to the pump housing. An initial sealing portion features an inner wall and an outer wall so that an annular space is defined therebetween. A top wall extends between the inner and outer walls. A coil spring is positioned within the annular space of the initial sealing portion and urges the inner wall into engagement with the piston rod and the outer wall into engagement with the pump housing.

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 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.

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.