Aircraft toilet drain assembly

Claim 2

A toilet drain assembly for an aircraft equipped with a toilet waste holding tank and an outlet tube leading from the holding tank to a portion of the aircraft provided with an access opening and a movable access panel for opening and closing the access opening, the toilet drain assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the aircraft with said open end facing towards the access opening spaced in an axially inward direction therefrom; a drain plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; and means connected to said cover responsive to the presence or absence of said drain plug in said nipple for preventing the access panel from closing the access opening when said drain plug is not present in said nipple and for allowing the access panel to close when said drain plug is present in said nipple.

Claim 3

A toilet drain assembly for an aircraft equipped with a toilet waste holding tank and an outlet tube leading from the holding tank to a portion of the aircraft provided with an access opening and a movable access panel for opening and closing the access opening, the toilet drain assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the aircraft with said open end facing towards the access opening spaced in an axially inward direction therefrom; a drain plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; and panel contacting means connected to said handle responsive to the presence or absence of said drain plug in said nipple for contacting the access panel to prevent it from closing the access opening when said drain plug is not present in said nipple and for allowing the access panel to close when said drain plug is present in said nipple; and securing means connected to said drain plug for releasably engaging said cover when said drain plug is connected to said nipple to secure said cover in position on the end of said nipple.

Claim 4

A toilet drain assembly for an aircraft equipped with a toilet waste holding tank and an outlet tube leading from the holding tank to a portion of the aircraft provided with an access opening and a movable access panel for opening and closing the access opening, the toilet drain assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the aircraft with said open end facing towards the access opening spaced in an axially inward direction therefrom; a drain plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; and panel contacting means connected to said handle responsive to the presence or absence of said drain plug in said nipple for contacting the access panel to prevent it from closing the access opening when said drain plug is not present in said nipple and for allowing the access panel to close when said drain plug is present in said nipple; and securing means connected to said drain plug for releasably engaging said cover when said drain plug is connected to said nipple to secure said cover in position on the end of said nipple.

Claim 5

A toilet drain assembly for an aircraft equipped with a toilet waste holding tank and an outlet tube leading from the holding tank to a portion of the aircraft provided with an access opening and a movable access panel for opening and closing the access opening, the toilet drain assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the aircraft with said open end facing toward the access opening spaced in an axially inward direction therefrom; a drain plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; a handle movably connected to said cover projecting in an axially outward direction therefrom towards the access opening, said handle mounted for limited motion relative to said cover between extended and depressed positions, said handle in the extended position preventing the access panel from closing the access opening; locking means connected to said handle responsive to the presence or absence of said drain plug in said nipple for locking said handle in the extended position when said drain plug is not present in said nipple and for releasing said handle for movement to the depressed position when said drain plug is present in said nipple; and engaging means secured to said drain plug releasably engaging said handle to said drain plug during movement of said handle to its depressed condition for thereafter maintaining said handle in its depressed position and for holding the cover in position on the end of said nipple.

Claim 6

A toilet drain assembly for an aircraft equipped with a toilet waste holding tank and an outlet tube leading from the holding tank to a portion of the aircraft provided with an access opening and a movable access panel for opening and closing the access opening, the toilet drain assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the aircraft with said open end facing toward the access opening spaced in an axially inward direction therefrom; a drain plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; a handle movably connected to said cover projecting in an axially outward direction therefrom towards the access opening, said handle mounted for limited motion relative to said cover between extended and depressed positions, said handle in the extended position preventing the access panel from closing the access opening; locking means connected to said handle responsive to the presence or absence of said drain plug in said nipple for locking said handle in the extended position when said drain plug is not present in said nipple and for releasing said handle for movement to the depressed position when said drain plug is present in said nipple; and engaging means secured to said drain plug releasably engaging said handle to said drain plug during movement of said handle to its depressed condition for thereafter maintaining said handle in its depressed position and for holding the cover in position on the end of said nipple.

Claim 7

A toilet drain assembly for an aircraft equipped with a toilet waste holding tank and an outlet tube leading from the holding tank to a portion of the aircraft provided with an access opening and a movable access panel for opening and closing the access opening, the toilet drain assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the aircraft with said open end facing towards the access opening spaced in an axially inward direction therefrom; a drain plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; a handle movably connected to said cover projecting in an axially outward direction therefrom towards the access opening, said handle mounted for limited motion relative to said cover between extended and depressed positions, said handle in the extended position preventing the access panel from closing the access opening; and locking means connected to said handle responsive to the presence or absence of said drain plug in said nipple for locking said handle in the extended position when said drain plug is not present in said nipple and for releasing said handle for movement to the depressed position when said drain plug is present in said nipple.

Claim 8

A toilet drain assembly for an aircraft equipped with a toilet waste holding tank and an outlet tube leading from the holding tank to a portion of the aircraft provided with an access opening and a movable access panel for opening and closing the access opening, the toilet drain assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the aircraft with said open end facing towards the access opening spaced in an axially inward direction therefrom; a drain plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; a handle movably connected to said cover projecting in an axially outward direction therefrom towards the access opening, said handle mounted for limited motion relative to said cover between extended and depressed positions, said handle in the extended position preventing the access panel from closing the access opening; and locking means connected to said handle responsive to the presence or absence of said drain plug in said nipple for locking said handle in the extended position when said drain plug is not present in said nipple and for releasing said handle for movement to the depressed position when said drain plug is present in said nipple.

Claim 9

A toilet drain assembly as defined in claim 4 wherein said locking means includes, at least one locking member movably connected to said handle for limited motion between a locking position and a released position, said locking member in the locking position engaging said cover with said handle to prevent movement thereof to its depressed position, said locking member in the released position being disengaged from said cover to free said handle for motion; and lock control means connected to said locking member contacting said drain plug for freeing said locking member for movement to its released position when said drain plug is present in said nipple, said lock control means preventing movement of said locking member to the released position when said drain plug is not present in said nipple.

Claim 10

A toilet drain assembly as defined in claim 5 wherein said lock control means includes, a control member connected to said handle for limited axial motion relative thereto having one end movable into contact with said drain plug, said control member adjacent an opposite end thereof contacting said locking member to control motion thereof between the locking and released positions; and biasing means acting on said control member to extend it relatively to said handle to an extended position in which said control member maintains said locking member in its locking position, axially inward movement of said handle moving said control member in a closing direction relative to said handle when said control member is in contact with said drain plug causing said control member to free said locking member for movement to its released position.

Claim 11

A toilet drain assembly as defined in claim 6 wherein, said handle includes a shaft mounted in and extending slidably through said cover for axial motion relative thereto, said shaft having, mounting means for mounting said locking member for radial movement relative to said shaft between said locking and released positions; and wherein, said control member is mounted on said shaft for axial sliding motion relative thereto, said one end of said control member projecting beyond the axially inner end of the said shaft into contact with said drain plug, said control member adjacent its opposite end having, a first cam region which is axially aligned with and contacts said locking member when said control member is in the extended position relative to said handle to support said locking member in its locking position; and a second cam region spaced axially, and recessed radially, from said first cam region, said second cam region being moved into axial alignment with said locking member upon a pre-determined extent of closing motion of said control member from its extended position relative to said handle thereby freeing said locking member for movement to the released position.

Claim 12

A toilet drain assembly as defined in claim 7 wherein said shaft and said control member comprise concentric outer and inner cylinders, respectively, mounted in axially sliding relation and wherein said locking member comprises at least one locking ball mounted in a lateral opening in said outer cylinder for motion between the locking position and the released position.

Claim 13

A toilet drain assembly as defined in claim 4 further including, biasing means connected between said cover and said handle for urging said handle from the depressed to the extended position.

Claim 14

A toilet drain assembly as defined in claim 4 further including: means connecting said cover to said mounting structure for motion of said cover from its position against and closing the open end of said nipple to a separated position in which said cover is spaced away from said nipple and projects outwardly through the access opening.

Claim 15

A toilet drain assembly as defined in claim 8 wherein said means for connecting said cover includes, a slotted hinge connected to said mounting structure and said cover enabling said cover to be rotated from the separated position to an intermediate position in which said cover is parallel to and spaced from the open end of said nipple and thereafter moved axially from the intermediate position into engagement with the end of said nipple extending thereacross.

Claim 16

A toilet drain assembly for an aircraft equipped with a toilet waste holding tank and an outlet tube leading from the holding tank to a portion of the aircraft provided with an access opening and a movable access panel for opening and closing the access opening, the toilet drain assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the aircraft with said open end facing toward the access opening spaced in an axially inward direction therefrom; a drain plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; and mutually engaging first and second securing means connected to said drain plug and said cover, respectively, for releasably securing said cover in position on the end of said nipple.

Claim 17

A toilet drain assembly for an aircraft equipped with a toilet waste holding tank and an outlet tube leading from the holding tank to a portion of the aircraft provided with an access opening and a movable access panel for opening and closing the access opening, the toilet drain assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the aircraft with said open end facing toward the access opening spaced in an axially inward direction therefrom; a drain plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; and mutually engaging first and second securing means connected to said drain plug and said cover, respectively, for releasably securing said cover in position on the end of said nipple.

Claim 18

A toilet drain assembly as defined in claim 12 wherein one of said securing means comprises a male engaging member and the other of said securing means comprises a female engaging member for releasably engaging said male member when said cover is positioned on the end of said nipple to thereby maintain said cover in such position.

Claim 19

A toilet drain assembly as defined in claim 13 wherein, said female engaging member includes, a housing fixedly connected to the associated one of said cover and said drain plug, said housing having an open ended slot therein communicating with a retainer pocket, said male engaging member entering said slot and becoming releasably trapped within said retainer pocket to secure said cover to said nipple, and biasing means for yieldably resisting release of said male engaging member from said retainer pocket.

Claim 20

A toilet drain assembly as defined in claim 14 wherein, said female engaging member comprises a generally tubular base fixedly secured to said drain plug, said slot extending in axial and peripheral directions with the open end thereof facing towards said cover; and wherein said male member comprises, a shaft connected to said cover slidable axially into said base; and a pin secured to said shaft positioned to enter said slot during motion of said shaft into said base and move into said retainer pocket.

Claim 21

A drain plug for use in an aircraft toilet system of the type including an outlet tube terminating in a drain nipple having internal recessed portions for engagement by the drain plug, the nipple being provided with a cover removably positioned on the end of the nipple extending thereacross, the cover being provided with an engagement member, the drain plug comprising, a base plate, gripping means secured to said base plate selectively movable into mechanical grippping engagement with the recessed portions of the nipple to fixedly secure said base plate to the nipple at a pre-determined inward spacing from the open end thereof; an expandable sealing member connected to said base plate for selective expansion into sealing engagement with the outlet tube to prevent leakage therefrom; and securing means fixedly secured to said base plate projecting axially therefrom on an opposite side from said sealing member for mating engagement with the engagement member on the cover to secure the cover in position on the end of the nipple.

Claim 22

A drain plug for use in an aircraft toilet system of the type including an outlet tube terminating in a drain nipple having internal recessed portions for engagement by the drain plug, the nipple being provided with a cover removably positioned on the end of the nipple extending thereacross, the cover being provided with an engagement member, the drain plug comprising, a base plate, gripping means secured to said base plate selectively movable into mechanical grippping engagement with the recessed portions of the nipple to fixedly secure said base plate to the nipple at a pre-determined inward spacing from the open end thereof; an expandable sealing member connected to said base plate for selective expansion into sealing engagement with the outlet tube to prevent leakage therefrom; and securing means fixedly secured to said base plate projecting axially therefrom on an opposite side from said sealing member for mating engagement with the engagement member on the cover to secure the cover in position on the end of the nipple.

Claim 23

A drain plug as defined in claim 16 for use with a cover wherein the engaging member on the cover is a male engaging member and wherein, said securing means includes a housing fixedly connected to said base plate, said housing having a slot therein having an open end facing towards the said cover and a retainer pocket, the male engaging member connected with cover entering said slot and becoming releasably trapped within said retainer pocket to secure the cover to the nipple.

Claim 24

A drain plug for use in an aircraft toilet system having an outlet tube and a drain nipple connected to the outlet tube, the drain nipple having internally recessed portions at a pre-determined location, the drain plug comprising, a base plate, releasable means mounted on said base plate for fixedly engaging said base plate with the recessed portions of the nipple; an expandable sealing member mounted on said base plate for selective expansion into sealing contact with the outlet tube to prevent leakage therefrom; a generally tubular housing fixedly secured to said base plate on the opposite side from said sealing member projecting outwardly; and at least one axially and peripherally extending slot extending through said housing, said slot having an open end facing towards the open end of the nipple and a closed end spaced axially inwardly therefrom, said slot at its axially inward end being relieved in an axially outward direction to define a pocket.

Claim 25

A drain plug for use in an aircraft toilet system having an outlet tube and a drain nipple connected to the outlet tube, the drain nipple having internally recessed portions at a pre-determined location, the drain plug comprising, a base plate, releasable means mounted on said base plate for fixedly engaging said base plate with the recessed portions of the nipple; an expandable sealing member mounted on said base plate for selective expansion into sealing contact with the outlet tube to prevent leakage therefrom; a generally tubular housing fixedly secured to said base plate on the opposite side from said sealing member projecting outwardly; and at least one axially and peripherally extending slot extending through said housing, said slot having an open end facing towards the open end of the nipple and a closed end spaced axially inwardly therefrom, said slot at its axially inward end being relieved in an axially outward direction to define a pocket.

Claim 26

A liquid handling assembly for a liquid handling installation having a tube leading to a portion of the installation provided with an access opening and a movable access panel for opening and closing the access opening, the liquid handling assembly comprising, an annular nipple connected to the tube, having an open end; mounting structure for connecting said nipple to the installation with said open end facing towards the access opening spaced in an axially inward direction therefrom; a plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; and means connected to said handle responsive to the presence or absence of said plug in said nipple for preventing the access panel from closing the access opening when said plug is not present in said nipple and for allowing the access panel to close when said plug is present in said nipple.

Claim 27

A liquid handling assembly for a liquid handling installation having a tube leading to a portion of the installation provided with an access opening and a movable access panel for opening and closing the access opening, the liquid handling assembly comprising, an annular nipple connected to the tube, having an open end; mounting structure for connecting said nipple to the installation with said open end facing towards the access opening spaced in an axially inward direction therefrom; a plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; and means connected to said handle responsive to the presence or absence of said plug in said nipple for preventing the access panel from closing the access opening when said plug is not present in said nipple and for allowing the access panel to close when said plug is present in said nipple.

Claim 28

A liquid handling assembly for a liquid handling installation having a tube leading to a portion of the installation provided with an access opening and a movable access panel for opening and closing the access opening, the liquid handling assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the installation with said open end facing toward the access opening spaced in an axially inward direction therefrom; a plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; and mutually engaging first and second securing means connected to said plug and said cover, respectively, for releasably securing said cover in position on the end of said nipple.

Claim 29

A liquid handling assembly for a liquid handling installation having a tube leading to a portion of the installation provided with an access opening and a movable access panel for opening and closing the access opening, the liquid handling assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the installation with said open end facing toward the access opening spaced in an axially inward direction therefrom; a plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; and mutually engaging first and second securing means connected to said plug and said cover, respectively, for releasably securing said cover in position on the end of said nipple.

Claim 30

A liquid handling assembly for a liquid handling installation having a tube leading to a portion of the installation provided with an access opening and a movable access panel for opening and closing the access opening, the liquid handling assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the installation with said open end facing towards the access opening spaced in an axially inward direction therefrom; a plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; and panel contacting means connected to said handle responsive to the presence or absence of said plug in said nipple for contacting the access panel to prevent it from closing the access opening when said plug is not present in said nipple and for allowing the access panel to close when said plug is present in said nipple; and securing means connected to said plug for releasably engaging said cover when said plug is connected to said nipple to secure said cover in position on the end of said nipple.

Claim 31

A liquid handling assembly for a liquid handling installation having a tube leading to a portion of the installation provided with an access opening and a movable access panel for opening and closing the access opening, the liquid handling assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the installation with said open end facing towards the access opening spaced in an axially inward direction therefrom; a plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; and panel contacting means connected to said handle responsive to the presence or absence of said plug in said nipple for contacting the access panel to prevent it from closing the access opening when said plug is not present in said nipple and for allowing the access panel to close when said plug is present in said nipple; and securing means connected to said plug for releasably engaging said cover when said plug is connected to said nipple to secure said cover in position on the end of said nipple.

Claim 32

A liquid handling assembly for a liquid handling installation having a tube leading to a portion of the installation provided with an access opening and a movable access panel for opening and closing the access opening, the liquid handling assembly comprising, an annular nipple connected to the tube, having an open end; mounting structure for connecting said nipple to the installation with said open end facing toward the access opening spaced in an axially inward direction therefrom; a plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; a handle movably connected to said cover projecting in an axially outward direction therefrom towards the access opening, said handle mounted for limited motion relative to said cover between extended and depressed positions, said handle in the extended position preventing the access panel from closing the access opening; locking means connected to said handle responsive to the presence or absence of said plug in said nipple for locking said handle in the extended position when said plug is not present in said nipple and for releasing said handle for movement to the depressed position when said plug is present in said nipple; and engaging means secured to said plug releasably engaging said handle to said plug during movement of said handle to its depressed condition for thereafter maintaining said handle in its depressed position and for holding the cover in position on the end of said nipple.

Claim 33

A liquid handling assembly for a liquid handling installation having a tube leading to a portion of the installation provided with an access opening and a movable access panel for opening and closing the access opening, the liquid handling assembly comprising, an annular nipple connected to the tube, having an open end; mounting structure for connecting said nipple to the installation with said open end facing toward the access opening spaced in an axially inward direction therefrom; a plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; a handle movably connected to said cover projecting in an axially outward direction therefrom towards the access opening, said handle mounted for limited motion relative to said cover between extended and depressed positions, said handle in the extended position preventing the access panel from closing the access opening; locking means connected to said handle responsive to the presence or absence of said plug in said nipple for locking said handle in the extended position when said plug is not present in said nipple and for releasing said handle for movement to the depressed position when said plug is present in said nipple; and engaging means secured to said plug releasably engaging said handle to said plug during movement of said handle to its depressed condition for thereafter maintaining said handle in its depressed position and for holding the cover in position on the end of said nipple.

Claim 34

A liquid handling assembly for a liquid handling installation having a tube leading to a portion of the installation provided with an access opening and a movable access panel for opening and closing the access opening, the liquid handling assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the installation with said open end facing towards the access opening spaced in an axially inward direction therefrom; a plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; a handle movably connected to said cover projecting in an axially outward direction therefrom towards the access opening, said handle mounted for limited motion relative to said cover between extended and depressed positions, said handle in the extended position preventing the access panel from closing the access opening; and locking means connected to said handle responsive to the presence or absence of said plug in said nipple for locking said handle in the extended position when said plug is not present in said nipple and for releasing said handle for movement to the depressed position when said plug is present in said nipple.

Claim 35

A liquid handling assembly for a liquid handling installation having a tube leading to a portion of the installation provided with an access opening and a movable access panel for opening and closing the access opening, the liquid handling assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the installation with said open end facing towards the access opening spaced in an axially inward direction therefrom; a plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith; a handle movably connected to said cover projecting in an axially outward direction therefrom towards the access opening, said handle mounted for limited motion relative to said cover between extended and depressed positions, said handle in the extended position preventing the access panel from closing the access opening; and locking means connected to said handle responsive to the presence or absence of said plug in said nipple for locking said handle in the extended position when said plug is not present in said nipple and for releasing said handle for movement to the depressed position when said plug is present in said nipple.

Claim 36

A toilet drain assembly for an aircraft equipped with a toilet waste holding tank and an outlet tube leading from the holding tank to a portion of the aircraft provided with an access opening and a movable access panel for opening and closing the access opening, the toilet drain assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the aircraft with said open end facing towards the access opening spaced in an axially inward direction therefrom; a drain plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith in a closed position of said cover; first means connected to said handle responsive to the presence or absence of said drain plug in said nipple for preventing the access panel from closing the access opening when said drain plug is not present in said nipple and for allowing the access panel to close when said drain plug is present in said nipple; and second means permanently connecting said cover to said mounting structure for movement from the closed position to an open position separated from said nipple, said second means locating said cover and said first means, in the open position and in any intermediate position between the open position and the closed position, in obstructing relation to the access panel to prevent it from closing the access panel.

Claim 37

A toilet drain assembly for an aircraft equipped with a toilet waste holding tank and an outlet tube leading from the holding tank to a portion of the aircraft provided with an access opening and a movable access panel for opening and closing the access opening, the toilet drain assembly comprising, an annular nipple connected to the outlet tube, having an open end; mounting structure for connecting said nipple to the aircraft with said open end facing towards the access opening spaced in an axially inward direction therefrom; a drain plug removably connected to said nipple extending thereacross spaced inwardly from said open end; a cover removably positioned across the open end of said nipple in contact therewith in a closed position of said cover; first means connected to said handle responsive to the presence or absence of said drain plug in said nipple for preventing the access panel from closing the access opening when said drain plug is not present in said nipple and for allowing the access panel to close when said drain plug is present in said nipple; and second means permanently connecting said cover to said mounting structure for movement from the closed position to an open position separated from said nipple, said second means locating said cover and said first means, in the open position and in any intermediate position between the open position and the closed position, in obstructing relation to the access panel to prevent it from closing the access panel.