YL flange coupling is referred to as "flange coupling", which is a rigid coupling. It is to connect two semi-couplings with flange respectively with two shafts by ordinary flat keys, and then connect the two semi-couplings together with bolts to transfer motion and torque. The bolts connecting the two half-couplings can use b-class ordinary bolts. The torque is transmitted by the friction torque on the joint surface of the two half-couplings.

YL flange coupling has two main structural forms: 1. Use bolts to realize two-axis alignment by hinged holes and transfer torque by bearing extrusion and shearing on bolt rod; 2. 2. The lug on one half coupling and the groove on the other half coupling are matched and aligned.

YL flange couplings can be made of gray cast iron or carbon steel. Cast steel or forged steel shall be used at heavy load or with circumferential speed greater than 30 m/s. YL flange coupling has a high requirement for the neutral of the two shafts. When there is a relative displacement of the two shafts, it will cause additional load in the parts and worsen the working condition.