Abstract: Interplate rubber members 15 are interposed between abutting front and rear ends of spring leaves 2A and 2B. The spring leaves 2A and 2B have paired curved portions 14A and 14B, respectively, which are symmetrically S-shaped with respect to a connected position of an axle 3 in side view. A curvature radius of continuous and mutually reverse curves of each of the curved portions 14A of the upper spring leaf 2A is greater than a curvature radius of continuous and mutually reverse curves of each of the curved portions 14B of the lower spring leaf 2B. The upper curved portions 14A have longitudinally outward bend starts longitudinally outward of longitudinally outward bend starts of the lower curved portions 14B and have longitudinally inward bend ends longitudinally inward of longitudinally inward bend ends of the lower curved portions 14B.

Abstract: Interplate rubber members 15 are interposed between abutting front and rear ends of spring leaves 2A and 2B. The spring leaves 2A and 2B have paired curved portions 14A and 14B, respectively, which are symmetrically S-shaped with respect to a connected position of an axle 3 in side view. A curvature radius of continuous and mutually reverse curves of each of the curved portions 14A of the upper spring leaf 2A is greater than a curvature radius of continuous and mutually reverse curves of each of the curved portions 14B of the lower spring leaf 2B. The upper curved portions 14A have longitudinally outward bend starts longitudinally outward of longitudinally outward bend starts of the lower curved portions 14B and have longitudinally inward bend ends longitudinally inward of longitudinally inward bend ends of the lower curved portions 14B.