Air motor and pump comprising such a motor

A compressed air motor comprising a piston and a housing, the piston being received in the housing and dividing the housing into two primary chambers of variable volume, the motor comprising:

• a first direct supply valve for supplying a first primary chamber of the two primary chambers and a second direct supply valve for supplying a second primary chamber of the two primary chambers, these two valves each being movable relative to at least one respective seat, the first valve and the second valve being mounted on a same stem movable relative to the housing in a direction parallel to the direction of movement of the piston, and the stem being configured to be moved between a first position and a second position by moving means activated by the piston,
• maintaining means for keeping the stem in at least one of its first and second positions,
• wherein the first and second valves are made at least partially from a ferromagnetic material, and wherein the maintaining means comprise at least a first maintaining magnet able to exert a first retaining force on the first valve, a second maintaining magnet able to exert a second retaining force on the first valve, a third maintaining magnet able to exert a third retaining force on the second valve and a fourth maintaining magnet able to exert a fourth retaining force on the second valve.