US 5,465,862 A · Aircraft servicing pit lid with lift control

Abstract

A closure apparatus for a subsurface pit for servicing an aircraft located beneath an aircraft servicing surface across which aircraft travel is provided with an improved spring biasing arrangement. The system employs separate springs interposed between the hollow body of the pit and the lid so as to urge the pit lid from its horizontal seated position toward a fully raised position. Obstructions are provided for separately intercepting and disengaging the springs from acting against the pit lid as the pit lid is opened through intermediate angular positions between the horizontal seated position and the fully raised position. By sequentially isolating the pit lid from the action of each of the springs, one at a time, the moment of spring force opposing closure of the lid more closely follows the moment of the force of gravity tending to close the lid. This substantially reduces the maximum manual force that is thereby required to overcome gravity in opening the pit lid. The preload of each spring is preferably individually adjustable so as to allow the spring force to be fine tuned to closely match the force of gravity throughout the arcuate path of travel of the pit lid.

Claims18

Dependent claims

In a closure apparatus for a subsurface pit for servicing aircraft located beneath an aircraft servicing surface across which aircraft travel wherein said pit has a hollow body, a lid mounting frame thereabove located flush with said aircraft servicing surface and defining a pit access opening into said hollow body, a lid strong enough to withstand the weight of the tires of an aircraft traveling thereacross and a hinge mechanism secured to said lid and secured relative to said hollow pit body at the periphery of said lid for carrying said lid in rotation about a horizontal axis between a horizontal position seated on said mounting frame and a fully raised position in which said lid resides at an angle relative to said aircraft servicing surface, the improvement comprising a plurality of biasing means interposed between said hollow pit body and said pit lid wherein all of said biasing means are arranged so as to initially urge said pit lid from said horizontal seated position toward said fully raised position, and means for disengaging at least one of said biasing means when said lid reaches an intermediate position as a result of a manual lifting force applied thereto in moving from said horizontal seated position toward said fully raised position and reengaging said at least one of said biasing means when said lid reaches said intermediate position in moving from said fully raised position toward said horizontal seated position.

A pit for servicing aircraft located beneath an aircraft servicing surface across which aircraft travel while on the ground comprising:

a hollow body defining a subsurface chamber, a lid mounting frame at the top of said hollow body defining an access opening to said subsurface chamber therewithin, a lid strong enough to withstand the weight from the tires of an aircraft traveling thereacross for covering said access opening, a lid hinge mechanism secured with respect to said lid mounting frame at a peripheral location relative to said pit lid and connected to said lid at a distance from the center of gravity of said pit lid, whereby said lid is rotated between a horizontal seated position in said lid mounting frame at which the weight of said lid acts at a maximum moment arm equal to the aforesaid distance of said center of gravity from said peripheral location, through an arc along which the weight of said lid acts at a moment arm that decreases as said center of gravity of said lid approaches vertical alignment with said peripheral location, and a raised fully opened position in which said lid resides at an angle relative to said aircraft servicing surface, a plurality of springs interposed between said lid and said hollow body, and spring disengaging means for disengaging at least one of said springs from said lid at an intermediate position of rotation of said lid between said seated and said fully opened positions, whereby all of said springs urge said lid from said seated position toward said intermediate position and less than all of said springs urge said lid from said intermediate position when a manual lifting force is applied thereto toward said fully opened position.

In an access lid assembly including a lid which is able to withstand the weight applied by the tires of an aircraft traveling thereacross and a mounting frame located atop a subsurface chamber used to service aircraft and defining an opening therewith and in which said lid is movable to a horizontal seated position, a hinge joining said lid to said mounting frame for upward rotation about a horizontal axis from said horizontal position through an arc of at least ninety degrees to a fully opened position, a plurality of springs interposed between said lid and said mounting frame and all acting in parallel to urge said lid in rotation from said seated position toward said fully opened position through a predetermined acute arcuate angle of rotation from said seated position that is short of said fully opened position, the improvement comprising disengaging means for isolating at least one of said springs from said lid once said lid reaches said predetermined acute arcuate angle as a result of a manual lifting force applied thereto in moving from said seated position toward said fully opened position, and less than all of said springs urge said lid toward said fully opened position beyond said predetermined acute arcuate angle.

Dependencies are inferred from the claim text.

Aircraft servicing pit lid with lift control

Life of this patent

Aircraft servicing pit lid with lift control

Life of this patent

Abstract

Claims18