本SAE推荐规程《拖车轴校准》的范围是确定主销中心线与其中点处的轴中心线之间的垂直关系的尺寸限制和方法。市场上可以买到各种类型的设备，这些设备可用于提供不同精度的测量，但没有一种可以得到SAE的认可。这里将介绍最基本的测量方法，但如果需要更高的精度，可以使用其他设备。

The scope of this SAE Recommended Practice, trailer axle alignment, is to identify the dimensional limits of, and a method to, establish a perpendicular relationship between the king pin centerline and the axle centerline at its midpoint. Various types of equipment are commercially available which can be used for this measurement which provides varying degrees of accuracy, but none can be endorsed by SAE.The most fundamental methods of measurement will be described here, but other equipment is available if a greater degree of accuracy is desired.