Patent ID: 8627843

Claim:
A gate valve comprising: a cylindrical gate housing that is solid except for a slot extending through a bottom of the cylindrical gate housing and towards a top of the cylindrical gate housing; the slot accommodating a seal assembly, the seal assembly including a gate having a top and a bottom, the top of the gate including a hole that passes through the top of the gate for receiving a feed screw, the hole including a shaped opening for loosely accommodating a stern nut, the hole also including a recess disposed in the top of the gate for accommodating a retention plate that is connected to the top of the gate, the feed screw passing through the retention plate and the recess, the shaped opening and the stem nut and into the hole, the feed screw threadably engaging the stem nut, the shaped opening providing a gap between the gate and the stem nut but preventing rotation of the stem nut within the shaped opening; the top of the gate being connected to a retention plate through which the feed screw passes, the retention plate also at least partially covering the shaped opening for retaining the stem nut within the shaped opening; the bottom of the gate including a groove for accommodating a seal; and wherein rotation of the feed screw causing extension of the seal assembly out of the slot or retraction of the seal assembly into the slot.