INSPECTION SHAFT HATCH Russian patent published in 2009 - IPC E02D29/12 

FIELD: construction.

SUBSTANCE: inspection shaft hatch consists of a housing (1) with a supporting projection (2) where lid (3) is installed (3) so that it can be removed by locking devices having two positions "open" and "close". The hatch is provided with fixing elements (8) to fix locking devices in a proper position. Each fixing element is represented with a tetrahedron located under the lid (3). The tetrahedron basis is made as a one-piece element together with the lid (3). The first two perpendicular sides are on the same level and located so that locking device (5) movement in angular direction can be restricted in "open" position. The other two perpendicular sides of tetrahedron are on two levels and located so that locking device (5) can be placed on the lower surface of the first side in "open" position, and correspondingly, on the lower surface of the second side in "close" position. Round groove is formed on the level of sides corresponding to "close" position by three sides of different level. Two opposite sides of the groove are located so that angular movement of locking device (5) is restricted. The housing (1), lid (3), locking devices and fixing elements (8) are made from polymer material. The hatch is provided with no less than three locking devices. The locking device (5) is implemented as a strike plate (18) with threaded bushing. The strike plate (18) has a side, which is rounded by circle radius concentrically equal to groove rounding circle. There are side pieces (20) in locking device (5) implemented as a one-piece element together with bushing. The said side pieces (20) are provided with holes for cutters.

EFFECT: removal of inspection shaft hatch lid is avoided when it is mechanically affected due to hatch locking improvement.

4 cl, 7 dwg