Multistage spindle drive for converting rotary motion into linear motion

A multistep spindle drive for converting a rotary movement into a linear withdrawal and extension movement with different speeds of withdrawal and extension, the drive comprising:

• an outer threaded spindle, with an outer threaded region having a outer threaded spindle thread pitch;
• an inner threaded spindle with an inner threaded region and with another threaded region having another thread pitch, said another thread pitch being different from said outer threaded spindle thread pitch, said inner threaded spindle being telescopically connected with said outer threaded spindle to form a threaded connection with said inner threaded region engaging said outer threaded region;
• a drive element, said inner threaded spindle being connected to said drive element;
• a nut engaged with said another threaded region of said another threaded spindle at a nut threaded connection;
• a friction-increasing coupling member connected to said outer threaded spindle and connected to said inner threaded spindle for applying force between said outer threaded spindle and said inner threaded spindle for increasing a frictional force at said threaded connection;
• and
• an output element connected to said outer threaded spindle via said nut, said output element having a load state and a no load state wherein in said load state a frictional force at said nut threaded connection is greater than a frictional force at said threaded connection for changing the speeds of withdrawal and extension.