Mobile crane having a releasable coupling connecting the lower carriage with the upper carriage

A mobile crane, comprising:

• an upper carriage having external gear teeth;
• a lower carriage releasably coupled to said upper carriage;
• a drive pinion rotatably mounted to said upper carriage and having gear teeth meshing with said external gear teeth of said upper carriage;
• a coupling having a holding ring connected to the lower carriage and an externally toothed ring rotatably mounted on said upper carriage which includes said external gear teeth;
• said holding ring having radially inwardly extending ribs and said externally toothed ring having radially outwardly extending ribs, said ribs being equally spaced and having gaps therebetween and at least partially spanning a common annular space and being concentric to an axis of rotation of said upper carriage;
• wherein said radially outwardly extending ribs of said external toothed ring are movable from an uncoupled position where said upper carriage and said lower carriage are uncoupled, a connected position where said upper and lower carriages are connected but not interlocked, and an interlocked position where said upper carriage and said lower carriage are coupled and interlocked by rotation of said externally toothed ring;
• and
• wherein said drive pinion and said externally toothed ring on said upper carriage remain meshed when said external toothed ring is in said uncoupled position, said connected position and said interlocked position.