The invention is a 3D surface
synchronizer, belonging to automobile driving device field, including: two-stage gear, inner conical ring, outer conical ring, medium ring,
synchronizer spring, tooth case, gear hub, slide block, one-stage gear, first groove, slide block groove, and second groove, where inner conical ring, outer conical ring and medium ring are set in sequence from inside to outside to compose a friction ring on the gear, the inner conical ring is covered on the
conical surface of the gear, the medium ring covered on the inner conical ring and the outer conical covered the medium ring, the medium ring is connected with the two-stage gear and one-stage gear by the grooves on the stage tooth, the slide groove is on the inner wall of the tooth case, the whole slide block is inserted in the groove of the gear hub, two
synchronizer springs tightly adhere to two sides of the gear hub, respectively, and the outer conical ring is set with groove at the big end. It largely enhances synchronous torque, thus shortens synchronous time and widens the
working range of the synchronizer, etc.