Abstract: A zipline trolley system comprises a cable, trolley, launcher, and a catch block. The launcher is fixed on the cable and comprises a substantially cylindrical inner body with a rigid outer body adapted to rotate about the inner body. A return spring attaches the inner body with the outer body. The catch block is also fixed on the cable and comprises a block with left and right retaining arms pivotably connected to the block and adapted to clasp onto the front plate of the frame of the trolley.