Patent ID: 8360489

Claim:
A cylindrical lever lock including a body assembly connected with a latch assembly at a front thereof, and pairs of attachment plates, plate assemblies and levers sequentially connected to inner and outer sides of the body assembly, respectively, wherein the inner and outer plate assemblies each comprise: a plate shaft molded of a metal plate; a spring cage fixedly connected to the plate shaft to receive a rotation spring; a spring holder molded of a metal plate and enabling the rotation spring to be elastically connected between the spring cage and the spring holder; a cover plate fixedly connected to the plate shaft, thereby fixedly inserting a spring cage cover between the cover plate and the spring holder for preventing separation of the rotation spring from between the spring holder and the spring cage; pairs of stopper protrusions, one pair of which are formed at a predetermined interval on an outer surface of the spring cage and the other pair are formed at another predetermined interval on an inner wall of a center hole of the spring cage cover; and fixing pieces protruding from inner and outer sides of a flanged rim part of the spring holder; and a first supporting protrusion formed at the flanged rim part of the spring holder so that a first bent end of the rotation spring is engaged with the first supporting protrusion and a second supporting protrusion formed on the outer surface of the spring cage so that a second bent end of the rotation spring is engaged with the second supporting protrusion so as to exert an elastic force on the levers, wherein the spring holder is disposed between and engages with the spring cage and the spring cage cover such that the spring holder is rotatable with the levers causing the fixing pieces to engage with the pairs of stopper protrusions as the levers are rotated, such that the levers are not rotated beyond a predetermined angle range.