Tilt mechanisms with internal clutches are designed to prevent over rotating of the mechanism. This feature is mostly found in mini blind tilt mechanisms, but can be found in other blinds as well.
A tilt mechanism clutch is simply a section of teeth missing from the internal gear as shown here. When installing a tilt mechanism like this, find the center point of the internal gear by rotating the tilter all the way one way until it reaches the clutch and stops. Make note of this position.
Rotate the tilt mechanism the other way until it stops again. Make note of this position. You may have to manually rotate the tilt mechanism as shown to get it to engage the gears after the clutch is reached.
Set the tilt mechanism hole exactly half way between the two stopping points. Now you can install your tilt mechanism.
Here’s a video that describes this process: