LOCKING DEVICE FOR INSPECTION PIT HATCH LOCKING Russian patent published in 2008 - IPC E02D29/14 

FIELD: manhole shafts and other inspection or access chambers, particularly covers thereof with means, which prevent unauthorized cover opening.

SUBSTANCE: locking device comprises rotary rod and locking member installed in orifice made in inspection pit hatch base. Rotary rod has engagement member created in upper end thereof. Locking member is provided with indication means arranged in upper locking member part and adapted to be installed in said orifice to prevent access to engagement member. Engagement member has head to be engaged with key. Indication means is created as plate mating to orifice made in the base. The plate has teeth defining comb structure. The teeth are diametrical about axis of rotation and are spaced a distance providing key installation therefrom. The teeth have L-shaped extensions at teeth ends so that extensions enclose engagement member from below. Rotary rod has control washer to provide space for teeth extension passage and retaining. Indication means may be formed of colored plastic. Plate may have individual number formed on outer plate surface.

EFFECT: increased tamper resistance and prevention of unauthorized access inside inspection pit, as well as extended range of functional capabilities and improved usage convenience.

2 cl, 3 dwg