Abstract: A drive motor of a dental handpiece for driving a cutting tool of the handpiece is provided that is connected to the dental handpiece on its front end side and includes a cylindrical casing; a rotor unit, which is rotatably supported inside the casing and outputs a driving force; a stator unit provided around the rotor unit inside the casing; and an air path which causes cooling air supplied from the rear end side of the drive motor to pass through an airtight cooling room circumferentially extending between the stator unit and the casing, and to be discharged from the rear end side.

Abstract: A drive motor of a dental handpiece for driving a cutting tool of the handpiece is provided that is connected to the dental handpiece on its front end side and includes a cylindrical casing; a rotor unit, which is rotatably supported inside the casing and outputs a driving force; a stator unit provided around the rotor unit inside the casing; and an air path which causes cooling air supplied from the rear end side of the drive motor to pass through an airtight cooling room circumferentially extending between the stator unit and the casing, and to be discharged from the rear end side.

Abstract: A low load burning burner comprising inner air flow nozzles, outer air flow nozzles and a fuel gas nozzle, and further having a motive air supply means, which is operated at the low load burning of a heating furnace, can maintain the furnace temperature uniform, and can heat materials arranged in the width direction of the furnace to a uniform temperature along the width direction of the furnace.

Abstract: A method of burning a fuel gas in a low NO.sub.x level in the exhaust gas is disclosed, wherein a radiant tube burner having concentrically arranged outer air flow nozzle, fuel gas nozzles arranged in a circle and inner air flow nozzle and having a particular structure is used and the fuel gas is burnt under a particularly limited condition.