What is "troll plate"

Troll \Troll\, n.

1. The act of moving round; routine; repetition.
   --Burke.

2. A song the parts of which are sung in succession; a catch; a round.

   Thence the catch and troll, while ``Laughter, holding both his sides,'' sheds tears to song and ballad pathetic on the woes of married life.
   --Prof. Wilson.

3. A trolley.

   Troll plate (Mach.), a rotative disk with spiral ribs or grooves, by which several pieces, as the jaws of a chuck, can be brought together or spread radially.

n. (context engineering English) A rotary disk with spiral ribs or grooves, by which several pieces, such as the jaws of a chuck, can be brought together or spread radially.