c thereopposite at a position between the brackets 64 near the front ends thereof furthest from the pivotal mounting of the base plate 62 thereto an electromagnet 69 is fixed to the brackets in a position acting to magnetically draw the front end of the base plate downwardly toward the electromagnet when activated stop features defined between the base plate and the brackets are arranged to block this downward movement of the plate 39 s rear end past a seated horizontal position of the base plate in which the bucket is oriented in its upright position in the illustrated embodiment the seated position stop is defined by contact between a flat bar shaped piece of ferromagnetic material 69 a fixed to the underside of the base plate 62 at the front end thereof to form the magnetically attractable portion thereof and a flat upper wall of a rectangular housing 69 b of the electromagnet 69 disposed between the front ends of the brackets 64 laterally outward from one of the brackets 64 near the front end thereof a first horizontal bolt 70 is fastened to an upturned flange 72 a at the distal end of a bottom plate 72 that spans between and projects laterally beyond the brackets therebeneath and on which the electromagnet 69 is mounted on the same side a second horizontal bolt 74 is fastened to an upturned flange 62 a of the base plate 62 at the front end thereof with the base plate 62 horizontally seated the second horizontal bolt 74.