Fork and fork-mounted limiting assembly

The invention relates to a fork and a fork-mounted limiting assembly. The fork comprises a fork arm, an installation cavity is formed in the fork arm, a limiting piece and a trigger piece are installed in the installation cavity, and a transmission structure is arranged between the limiting piece and the trigger piece; the weight of the limiting piece is greater than that of the trigger piece, sothat the limiting piece can enable the trigger piece to protrude upwards from the mounting cavity and be positioned at the high position of the limiting piece through a transmission structure by virtue of the weight of the limiting piece; or a return spring is arranged in the mounting cavity, and the trigger piece protrudes upwards out of the mounting cavity and is positioned at the high positionof the limiting piece under the action of the return spring; when the fork arm is inserted into an inserting pipe of a tray and supports the tray upwards, the upper wall surface of the inserting pipepushes against the trigger