渐开线花键的定心方式为齿形定心。受载时齿上有径向力，能起自动定心作用，有利于各齿受力均匀，强度高，寿命长。用于载荷较大，定心精度要求较高以及尺寸较大的联接，如航空发动机、燃气轮机、汽车等。压力角45°的花键多用于轻载、小直径和薄型零件的联接。

The involute spline is centering in the shape of the tooth. The tooth has radial force on the tooth, and it can play the role of automatic centering, which is beneficial to the uniform force of each tooth, high strength and long life. It is used for large load, high precision and large size connection, such as aero engine, gas turbine, automobile and so on. The spline with a pressure angle of 45 degrees is used for the connection of light, ***all diameter and thin parts.

销联接一般用来传递不大的载荷或作安全装置；另一作用是起***作用。常与带孔螺栓和六角开槽螺母配对使用，把销插入螺栓的孔与螺母的槽中，以防螺母松脱。销按形状分为圆柱销、圆锥销和异形销三类。

Pin connecti*** are generally used to transfer ***all loads or safety devices; the other is to play the role of . It is often paired with hole bolts and six angle slotting nuts to insert the pin into the hole of the bolt and the slot in the nut so as to prevent the loosening of the nut. The pin is divided into three types: cylindrical pin, conical pin and special pin.

凡是在轴毂联接中不用键、花键或销时的联接，统称为无键联接。无键联接中我们介绍两个常用的型面联接和过盈配合联接。

The connection of no key, spline or pin in the hub connection is called the keyless connection. In keyless joins, we two commonly used type face joins and interference fit connecti***.