Abstract A valve operator is disclosed which in a typical application is used to control an alumina slurry valve. In normal operation, the alumina slurry valve operator raises and lowers the valve stem (to open and close the valve) by driving a nut rotationally while the stem is locked against rotation. The locking means includes a sleeve keyed to the stem and coupled through gears to a no-back drive. Torque sensing means sense that the valve seat of the alumina slurry valve should be scraped and cleaned. Clutch means are then engaged to utilize the no-back drive to drive the gear train to rotate the stem in the same direction and at the same time as the nut but at a slightly slower speed of rotation, thereby to move the rotating stem very slowly in the downward direction, thereby to scrape and clean the valve seat. In some cases, it will be preferable to utilize the no-back drive to drive the gear train to rotate the stem in the same direction and at the same time and at the same speed as the nut, thereby to rotate the stem to scrape the valve seat but without moving the stem downwardly.
A reverse-locking clutch comprising: a. a housing; b. a shaft within said housing; c. input and output members mounted concentrically on said shaft; d. said input member being within said output member, said output member being adjacent said housing; e. said output member having a plurality of radial slots extending therethrough; f. a plurality of roller clutching elements within each of said slots; g. the sum of the diameters of said roller clutching elements exceed the length of the slot, whereby a portion of one of the roller elements projects beyond the output member in either an inward or outward radial direction; h. a plurality of camming recesses provided at spaced locations in the surface of said housing adjacent said output mEmber; i. a plurality of camming recesses provided at spaced locations in the outer surface of said input member; j. said input member containing a plurality of lugs extending radially outward for engaging said output member when said input member is driven rotationally; and k. spring-loaded means normally biasing said input member in such angular position relative to said output member that said camming recesses in the exterior surface of said input member are out of alignment with the slots in said output member.
Claim 2
Dependent Claim
205 words
A reverse-locking clutch comprising: a. a housing; b. a shaft within said housing; c. input and output members mounted concentrically on said shaft; d. said input member being within said output member, said output member being adjacent said housing; e. said output member having a plurality of radial slots extending therethrough; f. a plurality of roller clutching elements within each of said slots; g. the sum of the diameters of said roller clutching elements exceed the length of the slot, whereby a portion of one of the roller elements projects beyond the output member in either an inward or outward radial direction; h. a plurality of camming recesses provided at spaced locations in the surface of said housing adjacent said output mEmber; i. a plurality of camming recesses provided at spaced locations in the outer surface of said input member; j. said input member containing a plurality of lugs extending radially outward for engaging said output member when said input member is driven rotationally; and k. spring-loaded means normally biasing said input member in such angular position relative to said output member that said camming recesses in the exterior surface of said input member are out of alignment with the slots in said output member.