Through-fittings and below grade junction boxes equipped with same
View Patent ↗A through-fitting for a box or bulkhead contains a cavity which holds grease. When the through-fitting is tightened, grease from the cavity is automatically injected to seal the through-fitting. The through-fitting may be used in below-grade junction boxes. A junction box has various useful features. The junction box can be conveniently injection-molded. The junction box has application in fields including wired telephone connections.
1. A through-fitting comprising:
a stub having a bore extending therethrough;
a cap on the stub at an outer end of the bore, the cap movable in an inward direction relative to the stub;
a chamber containing an extrudable material, the chamber having a volume which is diminished by movement of the stub in the inward direction; and
a passage communicating between the chamber and the bore.
2. A through-fitting according to claim 1 wherein the chamber comprises an annular chamber defined between the cap and the outer end of the stub.
3. A through-fitting according to claim 2 wherein the passage comprises at least one axially-extending groove inside the bore.
4. A through-fitting according to claim 3 comprising a sleeve disposed within the bore and having an inwardly angled end surface, the sleeve movable axially within the bore in response to motion of the cap.
5. A through-fitting according to claim 4 wherein the passage comprises an aperture in the sleeve.
6. A through-fitting according to claim 5 comprising a burst member blocking the passage.
7. A through-fitting according to claim 6 wherein the burst member comprises a thin plastic member blocking the aperture in the sleeve.
8. A through-fitting according to claim 7 wherein the burst member and sleeve are integrally formed from plastic.
9. A through-fitting according to claim 1 comprising a burst member blocking the passage.
10. A through-fitting according to claim 1 comprising a piston slidably disposed within a cylinder wherein the chamber is defined between an end of the piston and the cylinder.
11. A through-fitting according to claim 1 comprising an elastromeric seal having a central aperture and located at an inner end of the bore.
12. A through-fitting according to claim 1 wherein the extrudable material comprises a silicone grease.
13. A junction box comprising a sealed enclosure and at least a first through-fitting according to claim 1 having the stub extending from a wall of the enclosure and the bore communicating between an interior of the inclosure and an exterior of the enclosure.
14. A through fitting according to claim 3 wherein the passage comprises an aperture in the stub.
15. A through fitting according to claim 14 comprising a burst member blocking the passage.
16. A through fitting according to claim 15 wherein the burst member comprises a thin plastic member blocking the aperture in the stub.
17. A through fitting according to claim 16 wherein the burst member and stub are integrally formed in plastic.