An example apparatus is disclosed herein comprising a valve that includes a valve body defining a fluid passageway between an inlet and an outlet, a flow control member in the fluid passageway, a stem coupled to the flow control member, and a bonnet coupled to the valve body. The stem extends through a channel in the bonnet. A section of the channel forms a bore. The bore is threaded. The apparatus includes packing in the channel to form a seal between the bonnet and the stem. The apparatus includes a worm wheel nut threadably engaged with the bore. The stem extends through an opening in the worm wheel nut. The apparatus also includes a worm meshed with the worm wheel nut. The worm is to rotate the worm wheel nut to cause the worm wheel nut to move and adjust a load on the packing.

An example apparatus is disclosed herein comprising a valve that includes a valve body defining a fluid passageway between an inlet and an outlet, a flow control member in the fluid passageway, a stem coupled to the flow control member, and a bonnet coupled to the valve body. The stem extends through a channel in the bonnet. A section of the channel forms a bore. The bore is threaded. The apparatus includes packing in the channel to form a seal between the bonnet and the stem. The apparatus includes a worm wheel nut threadably engaged with the bore. The stem extends through an opening in the worm wheel nut. The apparatus also includes a worm meshed with the worm wheel nut. The worm is to rotate the worm wheel nut to cause the worm wheel nut to move and adjust a load on the packing.