首先,明确自己需要做的测试，测试什么样的材料。厂家的测试有拉伸、弯曲、压缩、剪切、撕裂、剥离、两点延伸（需另配引伸计），在购买前要知道自己将来要测试的类型。根据自己的需求购买合适的拉力机。
First, make sure what kind of material you need to test. The manufacturer's test includes stretching, bending, compression, shearing, tearing, peeling, two-point extension (need to be equipped with an extensometer). Before purchasing, the manufacturer should know the type of test he will test in the future. Purchase the right tractor according to your own needs.
如果买家不太确定要做哪些实验，也可以听听仪器厂家的建议，一般情况下拉压弯都要做的，那么就可能要求伸长率、弯曲模量等参数。这样的话，就确定了，首先的是选择传感器的量程范围，先诂算拉压力范围值。然后需要什么样的速度，和行程高度，可以问自己的同行和查看相关标准。
If the buyer is not sure which experiment to do, he can also listen to the suggestion of the instrument manufacturer. In general, tension and compression bending should be done, then elongation, bending modulus and other parameters may be required. In this way, it is determined that the first step is to select the range of the sensor and calculate the range of the tension pressure. Then what kind of speed and height you need can ask your peers and check the relevant standards.
最后选择是要 什么样控制和操作系统的，一般的手动的和电动的仪器无法显示这些只能测一些简单数据，最大力和最大力的位移什么的，其余的都要自己计算。
The final choice is what kind of control and operating system is needed. General manual and electric instruments can not display these data, which can only measure some simple data, maximum force and maximum displacement, etc. The rest must be calculated by themselves.