Drive device

A drive device comprising:

• at least one first switchgear (9) and one second switchgear (11) in which each switchgear is actuatable by a spring force in an engaged direction and by hydraulic pressure in a disengaged direction;
• wherein during simultaneous actuation of said first switchgear (9) and second switchgear (11) in the engaged direction, an output (7) of the drive device is prevented from rotating so as to form a parking brake, and a disengaging device (26) simultaneously disengaging said first switchgear (9) and said second switchgear (11),
• for simultaneously disengaging said first switchgear (9) and said second switchgear (11), said disengaging device (26) has a disengaging device piston (25) which is separately pressurizable from the first and second switchgears (9, 11) and which, in a pressurized state, actuates both the first and second switchgear (9, 11) in the disengaging direction against the spring force acting on the first and second switchgears (9, 11);
• and
• the first switchgear piston (15) is situated in said first switchgear (9) which is disposed coaxially with the second switchgear piston (21) of the second switchgear (11) and coaxially with the disengaging piston (25) of the disengaging device (26).

A drive device comprising:

• a first switchgear (9) being biased toward an engaged position by a first spring (16) acting on a first piston (15) and being biased toward a disengaged position, against a force of the first spring (16), by pressurization of the first piston (15);
• a second switchgear (11) being biased into an engaged position by a second spring (22) acting on a second piston (21) and being biased toward a disengaged position, against a force of the second spring (22), by pressurization of the second piston (21);
• so that the first and second switchgears (9, 11) are biased to the engaged positions, by the respective first and second springs (16, 22), and the first and second switchgears (9, 11) thereby form a parking brake and maintain an output (7) of the drive device in a non-rotatable state;
• and
• a third piston (25), pressurizable separately from the first and second pistons (15, 21), actuates both of the first and second pistons (15, 21) and disengage the first and second switchgears (9, 11);
• wherein the disengaging piston (25) is coaxial with and forms a least a part of a cylinder for the first switchgear piston (15);
• and
• the first switchgear piston (15) is coaxial with and forms a cylinder for the second switchgear piston (21).