The difference between a normal horn and thrust horn.

The difference between a normal horn and thrust horn.

1. First you must have an understanding of radial bearing and thrust bearing.
The difference between radial and thrust bearing is the load direction of the axis.

In figure A, if the load is perpendicular of the bearing’s axis, then it is a radial bearing. (Normal Horn)

In figure B, if the load is at the same bearing’s axis and direction then it is a thrust bearing. (Thrust Horn)

2. RX-28’s normal horn structure
Below is a picture of a normal horn usage.
The load is perpendicular from the bearing’s axis.

3. RX-28’s thrust horn structure
Below is a picture of a thrust horn usage.
Because the thrust horn gets the load in the direction of the bearing’s axis, there is a bearing in between the dynamixel and horn.

4. Example Usages
The dynamixel used in chest part has been assembled with a thrust horn.
The dynamixel used in the arm has been assembled with a normal horn.
You can sort them out by at looking at the load’s direction.