Dog clutch having fluid pressure activated sliding internal gear

In a dog clutch assembly, comprising:

• a first shaft having an interface end portion with teeth on its outer diameter, the first shaft having a longitudinal axis;
• a second shaft having an interface end portion with teeth on its outer diameter, the second shaft having a longitudinal axis that is collinear with the longitudinal axis of the first shaft;
• a gap between the first shaft and the second shaft in a direction along the longitudinal axes of the shafts;
• an annular clutch having teeth along its inner diameter that engage the teeth of the first shaft and teeth of the second shaft when the clutch is in an engaged position, and that engage only the teeth of the first shaft or the teeth of the second shaft when it is in a disengaged position, wherein the engaged position and the disengaged position are linearly displaced from one another along the longitudinal axis of the shafts;
• an improvement which comprises:
• a driving actuator that drives the clutch between the engaged position and the disengaged position;
• wherein said driving actuator comprises:
• a first annular piston in direct contact with a second annular piston is rotatively connected to said clutch.