Shorter = Stronger
I need more steering-servo power. Rather than getting a new servo, can’t I just use a longer arm to get more leverage?
Servo-arm length does affect how much torque is applied to the steering system, but you’ve got it backward: A longer arm will give you less torque; however, you will get more steering throw (assuming the steering system can accommodate it). If you install a shorter servo arm, you’ll get the opposite: Torque goes up, but you’ll have less steering throw. If your current setup requires you to chop off a significant chunk of travel using endpoint settings, move the servo-arm linkage closer to the output shaft to put more of the servo’s travel (and torque) to work. (Nerd alert: The servo’s actual torque rating never actually changes, of course. Only the amount of torque transmitted via the servo arm changes.)
Let’s say we’ve got a servo rated at 100 ounceinch. As the term suggests, this servo should be able to lift a 100-ounce weight when fitted with a 1-inch arm. But if we installed a 2-inch arm, it would only be able to lift 50 ounces. 19
Moving the steering linkage away from the output shaft will increase steering throw but reduce torque—and vice versa.