Lubricating apparatus

Claim 1

Lubricating apparatus comprising: means defining a working chamber having a supply port for connection with a source of fluid pressure; means defining a pressure responsive wall for said working chamber operable to expand the working chamber from a contracted condition of minimum volume when the pressure in the working chamber is greater than a predetermined reference pressure, and to contract the chamber to said contracted condition when the pressure in said pressure chamber is less than said reference pressure; a control plunger mounted in said working chamber, said control plunger being engageable with said movable wall when the working chamber is in the retracted condition and movable with said movable wall when the pressure in said working chamber is greater than the reference pressure until the volume of the working chamber exceeds a predetermined maximum; a vent port connecting said working chamber with a pressure less than the reference pressure only when said control plunger is disengaged from said movable wall; a main body portion having a cylindrical bore formed therein; an end wall member closing the open end of said bore; said movable wall being received in said bore and cooperating with said end wall member to define said working chamber; a piston reciprocably mounted in said bore, one face of said piston defining said movable wall; said control plunger including a stem portion slidably mounted in said end wall member; an enlarged end portion formed on said stem and received in said working chamber, said enlarged end portion having a leading face engageable with said one face of said piston and a trailing face projecting generally radially outwardly from said stem portion and subject to the pressure in said working chamber when said leading face is engaged with said one face of said piston; an abutment projecting from said end wall into said working chamber for engaging said trailing face to maintain a space for fluid between said end wall and at least a portion of said trailing face; said vent port being formed in said control plunger with one end of said vent port communicating with said leading face and the other end of said vent port communicating with a surface of said control plunger at a location spaced from said one end a distance such that said other end is uncovered by said end wall member only when said trailing face is engaged with said abutment member; a resilient sealing member secured to said one face of said piston for engagement by said leading face of said control plunger to seal off said vent port from said working chamber; stop means for limiting the travel of said plunger with said piston and causing the plunger to disengage from said piston when the volume of the working chamber exceeds the predetermined maximum; said stop means comprising a stop pin mounted in the stem of said plunger on the opposite side of said end wall from said working chamber and engageable with said end wall member; a main passage for conducting fluid under presSure from a source to a fluid pressure operated device; a supply passage connecting said main passage with the supply port of said working chamber; means operable to permit flow through said supply passage only in response to fluid flow through said main passage; said last named means including a normally closed control valve in said main passage movable to an open position in response to a decrease in the pressure on the downstream side of said control valve with respect to the pressure on the upstream side of said control valve; a normally closed supply valve in said supply passage movable to an open position in response to fluid flow through the main passage past said control valve; means in said supply passage for adjustably restricting the flow through said supply passage to said working chamber; a return pressure branch passage connecting the downstream portion of said main passage with said bore on the opposite side of said piston from said working chamber; said bore being stepped with a reduced portion located on the opposite side of said piston from said working chamber, said piston having a reduced portion projecting into the reduced portion of said bore, the reduced portion of said bore having an end wall cooperable with the reduced portion of said piston to define a return pressure chamber, said return pressure branch passage extending between said return pressure chamber and said main passage such that pressure in said return pressure chamber urges said piston in the opposite direction to the pressure in said working chamber; a pumping chamber having an intake port adapted to be connected with a supply of lubricant and a delivery port, and means operable to expand and contract said pumping chamber in response to movement of said piston in said bore.