Hinge device for casings

A hinge device for a casing having a body portion and an upper cover, comprising:

• a substantially L-shaped mount plate having a vertical portion with a first hole and a second hole and a horizontal portion adapted to be securely mounted to said body portion of said casing;
• a pivotal axle comprising a mounting portion located on a first side of said vertical portion and adapted to be securely mounted to said upper cover of said casing, a flange portion also located on said first side of said vertical portion, and an extension with a portion thereof fittingly and pivotally received in said first hole of said vertical portion of said mount plate and having a threaded end portion;
• a first washer mounted on said extension of said pivotal axle and attached to said first side of said vertical portion of said mount plate between said vertical portion and said flange portion;
• a second washer mounted on said extension of said pivotal axle and attached to a second side of said vertical portion of said mount plate;
• a spring means mounted around said extension of said pivotal axle;
• a sleeve member mounted on said extension adjacent to said spring means, having a tubular portion and a flange;
• a torsion spring mounted on said tubular portion of said sleeve member, said torsion spring having an arm with a distal end thereof securely attached to said second hole in said vertical portion,
• a follower securely mounted on said threaded end portion of said pivotal axle for rotation therewith, said follower having a stop slightly biasing said torsion spring when the upper cover and the body portion is in a locked position, and said stop contacting said arm when the upper cover is opened to a pre-set maximum angle relative to the body portion;
• and
• a nut mounted on said threaded end portion of said extension to bias said spring between said member and said second washer;
• whereby said pivotal axle is freely pivotable relative to said spring means, when a desired position of said upper cover relative to said body portion of said casing is reached, said spring means biased by said nut exerts a longitudinal force on said pivotal axle, such that said flange portion of said pivotal axle is tightly against said first washer, thereby retaining said pivotal axle in position.