[1620]. Rocking or rolling valve. For opening and closing gradually and easily against pressure.

[1621]. Roll-up valve. For same purposes as the last named.

[Larger plate.]

[1622]. Sector full-way screw down valve, shown closed; when open the disc is up in the chamber out of the waterway.

[1623]. Double face valve; the spindle is screwed into the stuffing-box neck and the lower valve, the upper one being pinned to the spindle; the thread in the lower valve is twice the pitch of the upper thread.

[1624] & [1625]. Spring relief valves; the springs are adjusted to blow off at any stated pressure, which may be regulated by a screw or nut (not shown).

[1626]. Weighted lever relief valve or safety valve.

[1627]. Reducing valve, can be adjusted by the balance weight to pass fluids from a high pressure to any lower pressure.

[1628]. Another form, with spring balance adjustment and equilibrium valve.