Security cover for a valve box with a positively operated automatically lubricated locking mechanism

Abstract

A valve box lock for preventing unauthorized access to a shut off valve including a security bolt extending through a hole in a valve box cover and received into a threaded hole in a cam piece mounted to the undersurface of the cover, the cam piece is moved up and down by rotation of the security bolt in either direction. The cam piece engages a pair of locking plates which are moved radially out into engagement with an inner surface of the valve box to prevent removal of the cover when the security bolt is rotated in one direction, or are retracted radially to release the cover so as to be able to be removed. A automatic lubricating arrangement is associated with the security bolt to insure that it is able to be turned by excluding any.

Claims

1. A lockable cover for covering an open topped valve box so as to prevent access to a utility shut off valve located below said cover, said shut off valve accessible through an open top of said valve box only after said cover is removed therefrom; a locking mechanism mounted to an underside of said cover acting to prevent moving said cover off said open top of said valve box when said locking mechanism is in a locking condition, and allowing said cover to be moved off said open top of said valve box when said locking mechanism is in an unlocked condition; said locking mechanism including a pair of locking plates extending radially away from each other and toward an inner surface of said valve box, said locking plates mounted to the underside of said cover by a locking plate support arrangement so as to allow a limited radial back and forth movement of said locking plates to be able to engage or disengage an outer end of each of said locking plates with said inner surface of said valve box to prevent removal of said cover; said locking mechanism further including a cam mechanism operated by a security bolt having a head located atop said cover and further having a threaded shank extending down through an opening in said cover and extending further down to be threaded into a threaded bore in a cam piece forming a part of said cam mechanism, said cam piece engageable with both of said locking plates so as to move both of said locking plates radially out upon rotation of said security bolt in a first direction to raise said cam piece, and to move both of said locking plates radially inward upon rotation of said security bolt in an opposite second direction to lower said cam piece, thereby alternatively allowing locking or unlocking of said cover to prevent or allow removal of said cover from said open top of said valve box by rotation of said security bolt in said first or second directions respectively; a jam nut installed on said security bolt below said cover preventing an upward movement of said security bolt upon rotation of said security bolt in said second direction by said cover stopping upward movement of said jam nut so that when said security bolt is rotated in said second direction said cam piece is lowered; and, wherein a porous compressible washer is received on said security bolt, the washer is positioned above a top surface of said cam piece and below said jam nut, the washer has a lubricant absorbed therein, a portion of said is lubricant squeezed out of said porous compressible washer when said washer is squeezed between said jam nut and said cam piece, when said cam piece is raised by continued rotation of said security bolt in said first direction.

Description

DESCRIPTION OF THE DRAWING FIGURES

(1) FIG. 1 is a perspective view from above of a valve box cover having an attached lock mechanism according to the present invention, shown in a cover locked condition.

(2) FIG. 2 is a perspective view of a valve box cover with the locking mechanism shown in a released position.

(3) FIG. 3 is an exploded perspective view of a valve box cover and lock mechanism components shown in FIGS. 1 and 2.

(4) FIG. 4 is a view of a section taken vertically through the valve box cover and attached lock mechanism shown in FIGS. 1 through 3.

(5) FIG. 5 is a sectional view of a fragmentary portion of a valve box and an installed cover with the locking mechanism as shown in FIGS. 1-4 in a locked condition.

(6) FIG. 6 is a sectional view of the components shown in FIG. 5 with the lock mechanism in a released condition.

DETAILED DESCRIPTION

(7) In the following detailed description, certain specific terminology will be employed for the sake of clarity and a particular embodiment described in accordance with the requirements of 35 USC 112, but it is to be understood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims.

(8) Referring to the drawings, a cover 10 is shown adapted to be installed over the top of a valve box 12 which comprises an enclosure extending down from the surface of a paved area 14. The shut off valve (not shown) is located at some varying distance below the cover 10.

(9) The cover 10 is secured to the top of the valve box 12. A cover lock mechanism 16 mounted to the underside of the cover 10 so as to be suspended within the valve box 12. The cover 10 is normally prevented from being moved off the top of the valve box by the lock mechanism 16 which is normally in a locked condition.

(10) The cover lock mechanism 16 is attached to the underside of the cover 10 by being connected to four tapered posts 18 integral with the cover 10, which projecting down from the underside of the cover 10. A threaded hole 20 extends up into each post 18 (FIG. 4), each receiving a cap screw 22 which passes up through a respective one of the slotted holes 23 in a respective radially extending aligned locking plates 24A, 24B.

(11) The slotted holes 23 accommodate radial movement of the locking plates 24A, 24B created by up and down movement of a cam piece 34 caused by rotation of a security bolt 44 as described below. The cap screws 22 each first pass through aligned holes 26 in a pair of angle brackets 28A, 28B and through a spacer 27 installed in each of the slotted holes 23.

(12) The presence of the spacers 27 create a slight clearance between the brackets 28A, 28B and the locking plates 24A, 24B to allow limited radial movement of the locking plates 24A, 24B even after the screws 22 are tightened as will be described herein while attaching securely the locking plates 24A, 24B to the posts 18 and thus to the cover 10.

(13) Pairs of metal washers 25 and a felt washer 29 sandwiched between the same also help to freely allow radial movement of the locking plates 24A, 24B by up and down movement of the cam piece.

(14) The locking plates 24A, 24B each have an outer end surfaces 26A, 26B which are preferably curved to match the curvature of the inside surface 13 of the valve box 12.

(15) The outer ends of the angle brackets 28A, 28B are also curved to match the curvature of the end surfaces 26A, 26B of the locking plates 24A, 26B.

(16) A central rectangular opening 30 is formed in each locking plate 24A, 24B as well as an aligned rectangular notch 32, the notch 32 together providing a clearance to accommodate a central portion of the cam piece 34 extending between the inner ends of the locking plates 24A, 24B.

(17) The cam piece 34 has a pair of angled inwardly slightly tapered slots 36A, 36B extending up from the outer lower sides thereof of a width substantially greater than the thickness of the locking plates 24A, 24B.

(18) The cam piece 34 is comprised of a generally rectangular steel block with a central threaded hole 40 extending into the top thereof threadably receiving a security bolt 44. A counterbore 41 formed therein which is provided to collect any lubricant squeezed out from a thick felt washer 50 as further described below.

(19) The security bolt head 42 is formed with a custom drive feature having a shape unique to a utility company with a matching drive socket (not shown) as described above, enabling rotation of the security bolt 44 in either direction. As mentioned above, such security bolts 44 are commercially available and now in use by utilities which tightly control their distribution to their staff minimizing the possibility that such tools would by obtainable by unauthorized persons.

(20) A molded plastic cap 43 protects the bolt head 42 from the effects of exposure to the elements.

(21) The drive bolt shank 45 is threaded through a jam lock nut 46, and passes through a pair of metal washers 48 and thick felt washer 50 before being threaded into the hole 40 extending down into the top of the cam piece 34.

(22) The felt washer 50 is saturated with a special Teflon based non irritating grease, commercially available under the trademark Super Lube. This keeps the threaded shank 45 of the security bolt 44 lubricated to prevent seize up of the security bolt 44 over time. As seen in FIG. 5, the felt washer 50 is squeezed between the jam lock nut 46 and the top of the cam piece 34 when the cam piece 34 is elevated. Any lubricant squeezed out is collected in the counterbore 41 and causes the threads on the shank 45 to pick up lubricant each time the lock mechanism 16 is operated, maintaining a lubricant film on the threads of the security bolt 44 and the hole 40.

(23) The cover 10 may have a pair of lifting features 52 able to be engaged with a conventional lift pliers (not shown) in a known manner to conveniently enable lifting out of the cover 10 and attached lock mechanism 16 in order to remove the same from the valve box 12.

(24) A perimeter groove 54 in the cover 10 receives an elastomeric perimeter seal 55 which prevents debris from entering the valve box 12 and accumulating therein.

(25) Referring to FIGS. 4 through 6, the security bolt 44 passes through a clearance bore 57 in a cast in protuberance 58 and is threaded through the jam lock nut 46 and washer 48 which are drawn up to abut the underside protuberance 58 of the cover 10 when the security bolt 44 is in a release position with the lock mechanism 16 not engaged (FIG. 6).

(26) When the security bolt 44 is rotated in a first direction, the lower sides A of the cam piece slots 36A, 36B engage the radially inmost and axially lower corners 60 of the rectangular portion 62 of the locking plates 24A, 24B defined between the opening 30 and notch 32 of the locking plates 24A, 24B.

(27) The cam piece 34 is moved up by continued rotation of the security bolt 44, engaged with the inner lower corners 60 of the lower side A of the slots cams the locking plates 24A, 24B radially outward, causing the curved outer end surfaces 26A, 26B thereof into firm engagement with the inner surface 64 of the valve box 10 to securely engage the same.

(28) When the security bolt 44 is rotated in the opposite direction, the cam piece 34 is moved down bringing the upper sides B of the slots 36A, 36B into engagement with the upper and outer corners 64 of the cam piece 34 and camming the locking plates 24A, 24B back towards each other. The jam nut 46 restrains the security bolt 40 from moving up at this time to insure that the cam piece 34 is moved down by the rotation of the security bolt 40.

(29) The relatively great area of the engaged components generates a substantial resistance to any prying efforts exerted on the cover 10.