Amplitude adjustment mechanism for a vibratory mechanism of a surface compaction machine

A vibratory mechanism for a surface compaction machine, the vibratory mechanism comprising:

• a housing disposed within a compactor drum of the surface compaction machine;
• an eccentric shaft subassembly comprising:
• a first eccentric shaft disposed within the housing, wherein the first eccentric shaft is rotatable about an axis of rotation, the eccentric shaft comprising a first eccentric mass having a first center of mass that is offset from the axis of rotation;
• and
• a second eccentric shaft disposed within the housing, wherein the second eccentric shaft is rotatable about the axis of rotation, the second eccentric shaft comprising a second eccentric mass having a second center of mass that is offset from the axis of rotation;
• a ball screw subassembly comprising:
• a ball screw coupled to the first eccentric shaft;
• a ball nut coupled to the second eccentric shaft, wherein the ball screw is disposed within the ball nut;
• and
• a plurality of ball bearings disposed between the ball screw and the ball nut to reduce mechanical friction between the ball screw and the ball nut;
• a torque limiter coupled between the first eccentric shaft and the second eccentric shaft,
• wherein the torque limiter prevents relative rotation between the first eccentric shaft and the second eccentric shaft and a phase adjustment between the first eccentric shaft and the second eccentric shaft when a net torque applied to the torque limiter is less than a locking torque threshold, and
• wherein 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;
• and
• an actuator subassembly coupled to the ball screw to selectively apply a first linear force to the ball screw in a linear direction parallel to the axis of rotation to cause the ball screw to apply a first torque to the torque limiter via the first eccentric shaft;
• and
• a motor coupled to the second eccentric shaft to apply a second torque to the torque limiter via the second eccentric shaft,
• wherein the second torque does not overcome the locking torque threshold, and
• wherein the first torque and the second torque cause the net torque 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.

A method of adjusting a vibratory mechanism of a surface compaction machine, the method comprising:

• operating a motor to apply a first torque to a first eccentric shaft about an axis of rotation to rotate the first eccentric shaft,
• wherein the first torque is less than a locking torque threshold of a torque limiter coupled to the first eccentric shaft, and
• wherein rotating the first eccentric shaft causes concurrent rotation of a second eccentric shaft coupled to the torque limiter;
• and
• operating an actuator to selectively apply a second torque to the second eccentric shaft about the axis of rotation,
• wherein the first torque and the second torque apply a net torque to the torque limiter that is greater than or equal to the locking torque threshold of the torque limiter, and
• wherein applying the first torque and the second torque causes the second eccentric shaft to rotate with respect to the first eccentric shaft.