What is the relationship between radial torque and the force applied to the lever?
Torque is force multiplied by the perpendicular distance to the center of rotation. The HCT400's 75 kgf·cm of radial torque corresponds to 15 kgf at a 5 cm arm; the same torque drops to 7.5 kgf at 10 cm and rises to 30 kgf at 2.5 cm. This is why a force value is meaningful only together with the arm distance at which it is applied.
The relation is: Torque = Force × Arm distance. The torque the motor can produce is fixed; as you change the point where force is applied, the force you obtain changes inversely.
Example values for 75 kgf·cm:
- at 2.5 cm → 30 kgf
- at 5 cm → 15 kgf
- at 7.5 cm → 10 kgf
- at 10 cm → 7.5 kgf
What this means for installation matters: when connecting the motor's output arm to the manual lever, the closer the contact point is to the motor's center of rotation, the greater the force applied to the lever — but the total travel (the distance the lever will cover) shortens in the same proportion.
So two requirements must be met at the same time during installation:
- The applied force must exceed the peak force measured to move the lever.
- The travel obtained must be enough to take the lever from neutral to full stroke.
If these two conditions conflict, a model with higher torque capacity is required. In addition, the motor's own angular working range and the lever's mechanical end points must be matched during calibration.
Full coverage of this topic: What Does the HCT402 Achieve, How, and How Much? A Technical Review