The utility model provides a heavy vehicle drive bridge assembly of lightweight, relates to a transaxle assembly, and including axle housing assembly, main reducer assembly, semi -axis, brake assembly, hub brake drum assembly, camshaft, air chamber etc. The axle housing assembly includes casing, ring flange, central siphon, grommet, slide plate chair, goes up distance rod support, breather plug, reinforcing ring etc. Main reducer assembly formula main reducer assembly as an organic whole, this integral type main reducer assembly install on the reinforcing ring flange face of axle housing assembly, hub brake drum assembly is the synthetic brake drum assembly of hub, and brake assembly installs on the flange at axle housing assembly both ends, integral type main reducer assembly is connected to the one end of semi -axis, and the synthetic brake drum assembly of hub is connected to the other end of semi -axis. The utility model discloses an it is small, light in weight, simple structure is compact, and it is easy to make, low in production cost, maintenance is convenient, can satisfy each item performance index who pulls the semitrailer, is applicable to the demand in high -speed tractor, flatbed, tipper market.