Weight-adjustable dumbbell and dumbbell assembly

A weight-adjustable dumbbell, comprising a dumbbell grip bar assembly (2) and dumbbell plate groups (1) connected to two ends of the dumbbell grip bar assembly (2), wherein each of the dumbbell plate groups (1) comprises at least two dumbbell plates (10), and the dumbbell grip bar assembly (2) comprises a rotary plate selecting mechanism (21) for releasing or selecting at least one of the dumbbell plates (10) of each of the dumbbell plate groups (1);

• wherein the rotary plate selecting mechanism (21) comprises a central shaft (211), a handle tube (212) rotatably connected to the central shaft (211), and at least one hanging piece (214) rotatably connected to the central shaft (211), the at least one hanging piece (214) rotates synchronously with the handle tube (212);
• the dumbbell grip bar assembly (2) further comprises a safety stop mechanism (22), the safety stop mechanism (22) comprises a stop disc (222) and a lock head (223), the stop disc (222) rotates relative to the central shaft (211), the stop disc (222) rotates synchronously with the handle tube (212), and the lock head (223) is configured for unlocking/locking rotation of the stop disc (222);
• the safety stop mechanism (22) further comprises a lock case (221) fixed with the central shaft (211), a mounting tube (241) is convexly provided in the middle of the stop disc (222), a mounting hole (242) for inserting of the mounting tube (241) is formed in the middle of the lock case (221);
• at least one deformable fixture block (243), is convexly provided on a hole wall of the mounting hole (242) of the lock case (221);
• and an annular groove (244) for clamping of the at least one deformable fixture block (243) is provided on the periphery of the mounting tube (241).