An actuator rotational limiter mechanism for a multiple disk-stack, shared actuator hard disk drive includes an actuator comb with a cam-lock feature and an actuator limiter with a rotatable cam-roller that is engagable with the cam-lock feature to temporarily hold in place the actuator comb. The cam-lock feature may be positioned at or near a middle location of a back arm of the actuator armature, where the actuator comb being held in place by the cam-roller corresponds to the head slider being positioned on a load/unload ramp between adjacent disk stacks.