US 4,964,755 A · Manhole cover lock apparatus

Abstract

An improved cover lock apparatus comprises a rotatable and axially slidable crank plate connected to a plurality of retractable lock rods. The crank plate is disposed between the cover and a lock plate and is slidably and rotatably mounted to the lock plate. The crank plate has two upwardly protruding lock pins oriented to engage mating holes in the lock plate and is upwardly biased against the lock plate by a spring. When the lock pins are engaged in these holes, the crank plate cannot be rotated to retract the lock rods. Before the crank plate can be rotated to retract the lock rods, the lock pins must be disengaged from the mating holes in the lock plate by forcibly pushing down on the crank plate via a special lock key to overcome the spring bias that normally holds the crank plate pins in the engaged position. Once the crank plate is pushed downward enough to disengage the lock pins, it can be rotated to retract the lock rods.

Claims26

Dependent claims

Lock apparatus for locking a cover onto a seating base wherein the cover is a disk-shaped body with a top surface, a bottom surface, and a peripheral edge and the seating base has an annular flange adapted to support the cover by bearing on the bottom surface of the cover adjacent its peripheral edge, said lock apparatus comprising:

latch means attached to the bottom surface of the cover for realeasably engaging said annular flange in a manner that prevents movement of said cover away from said flange when said lock means is engaged;
latch actuator means connected to said latch means for engaging and disengaging said latch means, said latch actuator including a rotatable member that actuates said latch means by rotational movement;
lock means associated with said latch actuator means in such a manner that said lock means releasably secures said rotatable member against rotation when said latch means is engaged with said flange, said lock means being configured to require movement of said rotational member in a direction parallel to its axis of rotation before it is rotatable in an angular direction to disengage said latch means;
and
removable key means for moving said rotatable member in said axial direction and for rotating said rotatable member.

2 more elements

In a lockable cover having a plurality of radially extendable and retractable locking rods pivotally attached to a cranking means at their proximal ends and having their distal ends engaging an immovable locking flange fixed to a cover support base thereby locking the cover securely in position, and having a rotating means to rotate said cranking means to engage and disengage the lock rods, the improvement comprising:

a tamper-resistant locking means requiring a longitudinal movement and a rotational movement of the cranking means in order to engage and disengage the locking rods.

Dependencies are inferred from the claim text.

Manhole cover lock apparatus

Life of this patent

Manhole cover lock apparatus

Life of this patent

Abstract

Claims26