Manhole cover having a hinge, at least one jack and at least one arm that is slidable to a groove

摘要

Disclosed is a manhole includes a rectangular frame having first and second side walls and first and second end walls defining an opening in the frame. The manhole includes a first plug which has a first side which is pivotally mounted to the first end wall of the frame. A first hinge hingedly connects the first end wall of the frame and the first plug in a manner to allow play of the hinge axis in its mounting. The play of the hinge axis permits tilting of the first plug between an upright position and a closed position. In the upright position access is provided to the opening and in the closed position the plug bears an inner peripheral seating wall of the frame. The manhole includes a first jack which assists in opening and closing the first plug and is pivotally mounted at one end to the first plug and at another end to the frame. The manhole has a first self-locking arm with a first end pivotally mounted to the frame and a second end pivotally mounted to the first plug. The first self-locking arm is mounted for movement in a plane which is parallel to a plane in which the first jack moves. The first self-locking arm is operable to lock the first plug in the upright position. The manhole includes a fixed linear guiding groove formed in the frame and extending below the seating wall of the frame parallel to the seating wall. The manhole has a first stop secured to the frame, perpendicular to the second end wall of the frame. The first end of the self-locking arm is pivotally mounted to the frame and is slidable in the first linear guiding groove so that the first end of the self-locking arm approaches the second end wall of the frame during tilting of the first plug toward the closed position of the first plug. The first end of the self-locking arm bears on the first stop during tilting of the first plug toward the closed position of the first plug, causing the first plug to withdraw, towards the second end wall, adjacent to a hinged side of the first plug, so the first plug closes the opening in the frame.