Abstract: A passive lubrication system for use in a high speed print hammer mechanism to provide continuous lubrication to all print hammers over the lifetime of the mechanism. A plurality of hammer elements are pivotally engaged by a common pivot pin element. The lubrication system comprises a hammer block and a reservoir block both made of sintered material and each containing a supply of lubricant. The hammer block supplies lubrication to the pivot pin/hammer element bearing interfaces by capillary action. The reservoir block in turn supplies lubricant to the hammer block by capillary action to replenish the supply of lubricant as depleted in the hammer block. The reservoir block has a porous microstructure in which the porosity is at least equal to but preferably in coarser than the porosity of the porous microstructure of the hammer block.

Abstract: The disclosure describes in detail one of the most serious problems in connection with maintaining the operating life of print hammers at the high speeds of todays printers. Also described in detail is a structural arrangement to solve this problem without involving a major redesign of a print hammer module. A significant aspect of this solution is that a high speed print hammer is kept out of contact with structure that serves as a reservoir for the pivot pin lubricant.