To improve a reverse spring so as to cope with both a trip action and an automatic reset action of a reversal mechanism with a proper balanced state by a simple adjustment operation while assembling the reverse spring on a frame, without having to replace the reverse spring with an another spring component with different spring characteristics, such as, a conventional adjustment method in an adjustment process of the reversal mechanism performed, after assembling a thermal overload relay.
The reversal mechanism loaded on the thermal overload relay becomes an assembly of a reverse plate 11 supported on the frame 10, by using one end as an oscillating fulcrum and the reverse spring 12 of an extension coil spring stretched between the other end of the reverse plate 11 and a spring support section of the frame by sandwiching the fulcrum. When a normally-open contact 13 and a normally-closed contact are switched to an opening and closing position, respectively, by means of a reverse action of the reverse plate 11, plastic deformation is applied to a root side of a cantilever type support arm 10b, extending from the frame 10 as an adjustment means for spring tension against the reverse spring 12, and tension of the reverse spring 12 is adjusted at a proper range, by making the support arm bent in a stretching direction of the reverse spring 12.
TOYAMA KENTARO
MORISHITA FUMIHIRO
FURUHATA YUKIO
KAMOSAKI TAKEO
