Supporting leg structures

Claim 1

Supporting leg structure for the front end of a semi-trailer having at its front end a semi-trailer coupling to be coupled to and supported at said front end by supporting and mating semitrailer coupling means mounted on a tractor, said supporting leg structure being pivotably mounted to the front end portion of the sub-structure of said semi-trailer and including a power-driven operating mechanism connected between said supporting leg structure and said semi-trailer substructure for pivoting said supporting said leg structure between a substantially vertical operative supporting position for supporting the semi-trailer at its front end when the semi-trailer is disconnected from said tractor and an inoprerative position, in which the supporting leg structure is swung rearwardly out of contact with the ground to permit undisturbed travel of said semi-trailer in its coupled and front end supported condition in relation to said tractor; wherein said supporting means on the tractor is raisable and lowerable and said tractor has a power supply and a power driven operating mechanism connected to said power supply by selectively controllable conduit means supported on the tractor and by which said supporting means on the tractor is selectively raisable and lowerable for adjusting the height of the front end of the semitrailer in its coupled and supported position thereof in relation to the tractor; wherein said operating mechanism for supporting said supporting leg structure between said positions is connected to, and disconnected from, said selectively controllable conduit means on the tractor upon coupling and uncoupling, respectively, of said coupling means on the tractor and on the semi-trailer such that said operating mechanism on the semi-trailer is operable by power from said power supply on the tractor for pivoting tHe supporting leg structure to at least one of said operative and inoperative positions thereof when the semi-trailer is connected to and supported in a raised position of its front end by said supporting means on the tractor; and wherein the supporting leg structure includes a locking and unlocking system comprising a locking means adapted to automatically lock the supporting leg structure in its operative supporting position to said sub-structure of the semi-trailer upon pivoting the supporting leg structure into said operative position, and a power-operated unlocking mechanism associated with said locking means and adapted to be connected to, and controllable by, said selectively controllable conduit means on the tractor, said conduit supplying selectively to all said operating mechanisms, said locking and unlocking systems being, upon coupling of the semi-trailer to the tractor, connected to said conduit means and said conduit means being selectively controllable to transmit operating power also to the unlocking mechanism for unlocking the locking means before operating power is transmitted to said supporting leg structure operating mechanism.