In mechanical design, we often use ball screws and trapezoidal screws, which are two commonly used methods to change rotating motion into linear motion. Among them, ball screw because of the small friction, reversible, can also turn the linear motion into rotary motion, we call this transmission inverse efficiency transmission.

So, what's the difference?

What is the common form of two-end support structure? (Fixed-support)

Let's take a closer look

Different structure

First, let's look at structure, because structure determines characteristics.

Ball screw, it is also very well understood literally, is to roll with the ball, where the ball is rolling, of course, on the ball screw shaft.

Therefore, there is an arc outline on the lead screw shaft, which hovers on the shaft according to a certain lift Angle (lead Angle).

The ball is designed in the nut and rolls in the arc profile of the lead screw shaft, so it is rolling friction.

The principle of movement, that is, the screw pair, is simply understood, is similar to screw, we know that when screw, if the screw end limits the screw movement, then the threaded embedded parts will move along the axis of the screw.


Ball screw, it is the same reason, the screw shaft one or both ends are fixed along the axis, the motor is used to drive the screw rotation, then the nut with the steel ball will move along the axis of the screw.


Trapezoid lead screw and ball screw movement principle is the same, the difference is that the trapezoid lead screw in the ball, then the movement between the nut and the lead screw shaft, completely rely on mechanical contact to produce sliding, is sliding friction, so trapezoid lead screw is also called sliding lead screw.


Therefore, the structural difference between the two is summarized in one sentence: the ball screw is rolling friction, and the trapezoidal screw is sliding friction.