The Guts

• Inside the "bottle" jack is an inner working machine that is comprised of a reservoir, a main cylinder, a main piston, a pump piston, pump cylinder, check valves, a release valve, oil, oil ports and many seals to prevent air or oil leakage in the pressurized system. The check valves are the important part of the inner machine and serve one main function: to prevent oil within the ports from traveling the wrong way.
  
  

The Lift

• The pump piston connects to a lever that you move up and down with a long bar when you have the "bottle" jack placed under your vehicle. The up-and-down action of the lever moves the pump piston up and down within the pump cylinder. As you move the pump piston upward in the pump cylinder, it creates a suction that pulls open the first check valve and draws oil from the reservoir through the oil ports and up into the pump cylinder.
  
  As you bring the lever downward, the pump piston pushes the oil, closing the first check valve and opening a second check valve from the force of the oil the pump piston is pushing. The pressurized oil pushes through another oil port to the main cylinder where it lifts the main piston upward. As you lift the lever upward once again, the second check valve closes and the first check valve reopens to draw more oil into the pump cylinder, thus repeating the process until the main piston lifts up to the height you desire.
  
  

The Release

• After you have lifted the main piston and completed the work on your vehicle, it is time to lower the main piston. The "bottle" jack is equipped with a release valve that allows the pressurized oil to escape through a ported bypass around the two check valves. As the release valve opens fully, the oil rushes back to the reservoir and the main piston falls back down into the main cylinder.