a first end pivot axle 31 a second end pivot axle 32 a first extension element 146 and a first motion transfer link 810 coupled to first extension element 146 and a companion foot part 11 as suggested in fig5 a in illustrative embodiments first motion transfer link 810 is configured to provide means for moving a companion foot part 11 about foot pivot axis 12 relative to a neighboring foot part 11 as suggested in fig6 a and 6b in response to movement of first extension element 146 relative to companion first front leg 5 in illustrative embodiments first motion transfer link 810 comprises a pin 47 coupled to first extension element 146 and a guiding element 44 coupled to a second section 42 of foot part 11 to move therewith and formed to include a slot 45 receiving pin 47 for reciprocating sliding movement therein as suggested in fig6 a and 6b a first end of the first swivel trigger rod 28 is pivotably connected to a pivot axle 31 coupled to second leg 6 for pivotable movement about a pivot axis 31 a relative to the second leg 6 as suggested in fig5 a 5c a second end 32 e of the first swivel trigger rod 28 is connected to a first end of.