一個切向鍵只能傳遞一個方向的轉矩，傳遞雙向轉矩時，須用互成120°～130°角的兩個鍵。用于載荷很大，對中要求不嚴的場合。由于鍵槽對軸削弱較大 ，常用于直徑大于100mm的軸上。

A tangent key can only transfer the torque of one direction. When the two-way torque is passed, the two keys of 120 to 130 degrees are required. An occasion for heavy load and no strict requirement. As the keyway is greatly weakened to the axis, it is often used on a shaft with a diameter larger than 100mm.

花鍵聯(lián)接由內(nèi)花鍵和外花鍵組成。內(nèi)、外花鍵均為多齒零件，在內(nèi)圓柱表面上的花鍵為內(nèi)花鍵，在外圓柱表面上的花鍵為外花鍵。顯然，花鍵聯(lián)接是平鍵聯(lián)接在數(shù)目上的發(fā)展。

The connection of the spline is made up of the inner and outer spline. The inner and outer spline are multi tooth parts, and the spline on the surface of the inner cylinder is the inner spline, and the spline on the outer cylindrical surface is the outer spline. It is  that the spline connection is the development of the number of flat bond connecti.

漸開線花鍵的定心方式為齒形定心。受載時齒上有徑向力，能起自動定心作用，有利于各齒受力均勻，強度高，壽命長。用于載荷較大，定心精度要求較高以及尺寸較大的聯(lián)接，如航空發(fā)動機、燃氣輪機、汽車等。壓力角45°的花鍵多用于輕載、小直徑和薄型零件的聯(lián)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, small diameter and thin parts.