Hammer having a two part body

A hammer comprising:

• a housing including an upper housing member and a lower housing member, the housing defining a chamber, the upper housing member having a first pressure source of pressurized hydraulic fluid or pressurized air;
• a piston reciprocating inside the chamber, the piston including at least a first surface which communicates with the first pressure source to move the piston in a first direction;
• a reciprocating work tool residing at least partially inside of the chamber, an upper part of the work tool being struck by the piston as the piston moves in the first direction inside the chamber to transfer force from the piston to a tip of the work tool, the tip being formed opposite the upper part and residing outside of the chamber, the upper part of the work tool being housed inside the lower housing member;
• a tool retention member removably attached to the lower housing member, wherein when the tool retention member is attached to the lower housing member the work tool cannot be removed from the chamber and when the tool retention member is removed from the lower housing member, the work tool may be removed from the chamber for replacement;
• an engaging structure associated with the upper housing member and the lower housing member and configured to permit the engagement and disengagement of the upper housing member with the lower housing member by relative rotation of the upper housing member and the lower housing member, the engaging structure including mutually engaging mating surfaces on the upper housing member and lower housing member;
• and
• a prestressing structure configured to urge the lower housing member in the first direction away from the upper housing member, the prestressing structure including at least one jacking screw positioned between the upper housing member and the lower housing member.

A hammer comprising:

• a housing including an upper housing member and a lower housing member, the housing defining a chamber, the upper housing member having a first pressure source of pressurized hydraulic fluid or pressurized air;
• a piston reciprocating inside the chamber, the piston including at least a first surface which communicates with the first pressure source to move the piston in a first direction;
• a reciprocating work tool residing at least partially inside of the chamber, an upper part of the work tool being struck by the piston as the piston moves in the first direction inside the chamber to transfer force from the piston to a tip of the work tool, the tip being formed opposite the upper part and residing outside of the chamber, the upper part of the work tool being housed inside the lower housing member;
• an engaging structure associated with the upper housing member and the lower housing member and configured to permit the engagement and disengagement of the upper housing member with the lower housing member by relative rotation of the upper housing member and the lower housing member, the engaging structure including mutually engaging mating surfaces on the upper housing member and lower housing member;
• and
• a prestressing structure configured to urge the lower housing member in the first direction away from the upper housing member, the prestressing structure including at least one jacking screw positioned between the upper housing member and the lower housing member.