Automatic pneumatic hydraulic jack

Claim 1

An automatic hydraulic jack comprising: a large cylinder having a closed end an open end and an inner diameter; a large piston operably slidably mounted in said large cylinder adapted to protrude at one end through said open end of said cylinder; a first hydraulic fluid chamber at the closed end of said large cylinder; hydraulic fluid in said first chamber; a hydraulic fluid storage tank containing hydraulic fluid; a first hydraulic fluid flow channel connecting said first chamber with said storage tank; a manually operated valve in said first flow channel to close said channel during operation of the jack and open said channel after use thereof; a small cylinder closed at both ends having an inner diameter substantially smaller than the inner diameter of said large cylinder; a small piston slidably mounted in said small cylinder to reciprocate therein between top and bottom dead center positions comprised of a first end, a second end and a connection rod between said first and second ends holding said first and second ends in spaced relationship with respect to each other and having an outer diameter smaller than the inner diameter of said small cylinder to form an annular chamber between said ends; an air chamber between said first end of said small piston and the respective end of said small cylinder; a second hydraulic fluid chamber containing hydraulic fluid between said second end of said small piston and the respective end of said small cylinder; a second hydraulic fluid flow channel connecting said second chamber to said storage tank; a one-way valve in said second flow channel adapted to allow fluid from said storage tank to flow into said second chamber; a third hydraulic fluid flow channel connecting said second chamber to said first chamber; a one-way valve in said third flow channel adapted to allow hydraulic fluid to flow from said second chamber into said first chamber; an airflow control valve means operatively mounted adjacent said small cylinder having an air inlet, a first air outlet connected to said air chamber, a second air outlet connected to said storage tank, an exhaust outlet connected to the atmosphere, a control member, a control conduit and an exhaust conduit in said control member, and shifting means on said control member extending into said annular chamber in said small cylinder operatively associated with said small piston to be engageable by said first and second ends thereof as said small piston reciprocates to alternately shift said control member between a power position wherein said air inlet is connected through said control conduit to said first air outlet and a return position wherein said air inlet is connected through said control conduit to said storage tank and said air chamber is connected through said exhaust conduit to said exhaust outlet; and means to supply air under pressure to said air inlet; so that when said small piston is at top dead center said control member is in the power position and directs pressurized air into said air chamber to drive said small piston in a power stroke to displace hydraulic fluid from said second fluid chamber into said first fluid chamber to operate said large piston, and when said small piston is at bottom dead center said control member is shifted into the return position to direct pressurized air into said storage tank to drive said small piston in a return stroke toward top dead center where said control member is again shifted into a raising position to again operate said large piston.