Disk 1 rotates about fixed axis A. Weights b are rigidly secured to links 2 which are connected by turning pairs B and C to disk 1 and links 3. Lever 6, rotating about axis A, is connected by turning pairs E to links 3. Springs 4 and 5 pull links 2 toward the hub of disk 1. When disk 1 rotates, weights b move outward by overcoming the resistance of springs 4 and 5. This turns lever 6 to close ports a of eccentric 7. The amount by which ports a are closed depends upon the speed of rotation of disk 1. This regulates the admission of steam.
$812$LW,G$