The Pull Out force requirement is a function of the torque applied to the wheel (a combination of vehicle mass, gradient and tyre radius), which attempts to push the pawl out of engagement generating a large friction force in the roller.
The Engagement force requirement is defined by the spring rate and preload plus safety factors.The function of the actuator is to compress the spring to store energy. Engagement is then forced by the roller-pawl geometry. The latching force must be sufficiently high to prevent bounce out during dynamic engagements.