Air balancing device

An air balancing device for balancing a working force of a piston of a cylinder with a weight of a body to be carried, comprising a pressure regulating valve for adjusting a pressure in a supply/discharge passage to a pressure balanced against the weight of the body to be carried, the supply/discharge passage being connected to a working chamber of the cylinder for raising and lowering the body to be carried, the air balancing device further comprising

• a control valve for increasing and decreasing a pressure in a control passage in accordance with a balance between the weight of the body to be carried and a working force in a reaction force chamber to which a pilot pressure is introduced from the control passage,
• the pressure regulating valve comprising a pressure regulating chamber connected to the control passage via an opening/closing valve, a pilot chamber to which the pilot pressure from the control passage is constantly introduced, and a control chamber to which a pilot pressure from the supply/discharge passage is introduced, the pressure in the supply/discharge passage being adjusted to a pressure balanced against the weight of the body to be carried in accordance with a balance between a working force in the pressure regulating chamber and working forces in the pilot chamber and the control chamber.