Spring hinge

Claim 1

A hinge comprising: (a) a first leaf having spaced apart first and second knuckles provided with axially aligned bores of equal diameter which define a hinge axis; (b) a second leaf having a knuckle located between the first and second knuckles of the first leaf and also having a bore which is equal in diameter to the bores of the first leaf and aligns axially with the bores of the first leaf; (c) a unitary pivot extending through the bores of the knuckles for the first and second leaves and being capable of being installed in and removed from the bores as a unit, the pivot including: (1) a first hinge pin element located in the bore of the first knuckle for the first leaf and in the bore of the knuckle for the second leaf and having a cylindrical portion at least within the bore of the knuckle for the second leaf and also having a threaded portion, (2) a second hinge pin element located in the bore of the second knuckle for the first leaf and in the bore of the knuckle for the second leaf and including a cylindrical portion that is at least in the bore of the second knuckle for the first leaf and also having a threaded portion that is presented generally toward the threaded portion of the first hinge pin element, (3) a spacer located between and being engaged and axially aligned with the hinge pin elements for preventing the hinge pin elements from moving axially together so as to establish a predetermined spacing between the cylindrical portions, and (4) a coil-type torsion spring surrounding the spacer and being within the bore of the knuckle for the second leaf and at one end being threaded onto the threaded portion of the first hinge pin element and at its other end being threaded onto the threaded portion of the second hinge pin element such that the ends of the springs will not rotate relative to the pin elements onto which they are threaded, nor will they move axially off of the pin elements, the spring holding the two hinge pin elements together with the axial spacing between the pin elements when they are so held being substantially that established by the spacer so that the spacing between the pin element is substantially fixed at all times, the spring being small enough in diameter to slide through the bores of the knuckles, at least one of the hinge pin elements being no greater in diameter than the bores of the knuckles, so that when the pivot unit is not secured to any one of the knuckles, it may be moved as a unit axially through the bores and out of the knuckles; and (d) first locking means for securing the first hinge pin element against rotation with respect to the first knuckle of the first leaf and second locking means for securing the second hinge pin element against rotation with respect to the knuckle of the second leaf, so that when the spring is twisted, the torque it exerts on the hinge pin elements will be transmitted to the leaves, at least one of the locking means including a securing element which extends transversely from the knuckle to the hinge pin element that it secures and is removable from the knuckle and hinge pin element, so that the two may be detached, the other locking means being arranged to, upon manipulation, detach the hinge pin element and knuckle with which it is associated, whereby the pivot may be driven as a unit from or driven as a unit into the aligned bores of the knuckles, and when so driven, will remain unitary and of a fixed length.