This invention provides a lifting mechanism suitable for standard Brinell or Vickers
hardness tests, comprising a bottom mounting plate, a support column, a guide mounting plate, a screw jack, and a lifting tray
assembly. The lifting tray
assembly includes a tray and a main guide shaft. A receiving groove is provided at the bottom of the main guide shaft. The screw jack has an output screw, the top of which is connected to an adapter. The adapter abuts against the top wall of the receiving groove. A clearance groove is provided on the outer wall of the adapter near the output screw end. A
set screw is also screwed onto the main guide shaft, with one end extending into the clearance groove. When the tray becomes stuck due to the main guide shaft, the screw jack descends, the adapter contacts the
set screw, and as the adapter continues to descend, it pulls the main guide shaft downward, allowing the main guide shaft and the output screw to descend synchronously, preventing damage to the lifting mechanism and avoiding major safety accidents.