In front loaders designed for drive-in attachment to tractors, two telescopic struts are pivotable between a stowed retracted position alongside the boom assembly which carries the bucket; a first deployed extended position for supporting the rear end of the detachable main portion of the loader, aided by auxiliary struts, when it is not attached to the tractor; and a second deployed extended position, in which the struts engage with abutments on the sub-frame which carries both the boom assembly and the hydraulic cylinders for pivoting the boom assembly and are secured to said cylinders, for locking the boom assembly in its fully raised position whilst the detachable main portion is attached to the tractor.