To provide an improved spring-loading structure for use in a locking differential gear.

A spring-loading structure for use in a locking differential gear involves a plurality of spring-loading assemblies. The spring-loading assembly comprises a single coil spring 224 mounted at its one end with a spring cap member 228 serving to separate the coil spring 224 from a locking pin 226 of which one end lies inside an oversize spring bore 242. The cap member 228 comprises a disk part 228a of outside diameters equal to or larger than that of the coil spring 224, and a central plug part 228b adapted to be situated inside the coil spring 224. The coil spring 224 is supported at its one end by the disk part 228a only so as to be separated from the locking pin 226. The disk part 228a has diameters smaller than the width of an access opening 232 opening on the oversize spring bore 242 formed in a clutch member 202 or 204. The coil spring 224 mounted with the cap member 228 may be thus inserted into the spring bore 242 through the access opening 232.