A pneumatic oil pump comprising:
- a cylinder having a central bore defined longitudinally through the cylinder, and a sealed front end and a sealed rear end;
- a recess defined in an inner surface of the central bore of the cylinder near a middle of the cylinder;
- an air connector mounted in the front end of the cylinder;
- an actuating valve mounted in the front end of the cylinder and communicating with the air connector and the central bore of the cylinder;
- a first piston movably mounted in the central bore to divide the central bore into a first chamber to be selectively communicating with air by means of the actuating valve and a second chamber and having:
- two seals respectively mounted around the first piston at each end of the first piston;
- an inlet passage defined in the first piston between the seals;
- a cavity defined in the first piston to communicate with the inlet passage;
- a first outlet passage defined in the first piston to communicate with both the first and the second chambers of the cylinder;
- an inner piston movably received in the cavity in the first piston;
- a rod secured to the inner piston and extending into the first chamber of the cylinder;
- and
- a valve disk secured to the rod to close a passage between the outlet passage and first chamber of the cylinder;
- a piston seat securely attached to the first piston on a side facing the rear end of the cylinder;
- a second outlet passage defined in the piston seat and aligning with the first outlet passage in the first piston;
- a ventilative, sound-absorbing member mounted between the air outlets of the first piston and the piston seat;
- a drive rod secured to the piston seat;
- a piston spring mounted around the drive rod and located between the sealed end of the cylinder and the piston seat to provide a restoration force to the piston seat and the first piston;
- an exhaust valve mounted on the cylinder to selectively allow the communication of the second chamber with the air for controlling the exhaust of air;
- a pedal pivotally mounted on the cylinder and having one end aligning with the actuating valve;
- an oil reservoir mounted on the rear end of the cylinder;
- an oil channel defined in the rear end of the cylinder to communicate with the oil reservoir;
- a first ball and spring combination movably received in the oil channel to close the communication between the oil channel and the oil reservoir;
- a rod base attached to the rear end of the cylinder and facing the front end of the cylinder and having
- a passage aligning and communicating with the oil channel defined in the rod base for the drive rod to extend into the passage of the rod base;
- an oil discharge passage defined in the cylinder and communicating with the oil channel;
- an oil discharge connector mounted on the cylinder and communicating with the oil discharge passage to be adapted to connect to a hydraulic device.