Abstract: An adjustment mechanism for a vibratory mechanism of a surface compaction machine, the adjustment mechanism includes a torque limiter coupled between the first eccentric shaft and the second eccentric shaft that prevents relative rotation between the shafts and a phase adjustment between the shafts when a net torque applied to the torque limiter is less than a locking torque threshold. Application of a net torque to the torque limiter that is greater than or equal to the locking torque threshold causes the first eccentric shaft to rotate with respect to the second eccentric shaft. An actuator subassembly selectively applies a linear force cause a first torque to be applied the first eccentric shaft sufficient to apply a net torque to the torque limiter that is greater than or equal to the locking torque threshold to cause the first eccentric shaft to rotate with respect to the second eccentric shaft.