Patent ID: 8047302

Claim:
A handheld drilling and/or striking hammer, comprising: a tool holder; a percussion mechanism that acts on a tool that is held in the tool holder; a housing connected to and extending away from the percussion mechanism; a transmission that drives the percussion mechanism to reciprocate and that is at least partially enclosed by the housing; a hood that covers the housing, defining a void space therebetween; a vibration damping system extending between and connecting the hood and the housing, while permitting the hood and the housing to move with respect to each other, a lubricating device that lubricates at a portion of at least one of i) the percussion mechanism, ii) the transmission, and iii) the tool holder and that includes, a reservoir holding a volume of lubricant therein and being attached to the hood; a flexible tube extending between the reservoir and the housing and directing lubricant therebetween at a variable flow rate, the flexible tube being constructed and positioned so as to flex while the hood and housing move with respect to each other so as to impart shear forces in lubricant in the tube that reduce the lubricant's viscosity to automatically vary the lubricant flow rate from the reservoir to the housing as a function of tool stress.