Restraint systems and restraint system methods

Passenger restraint systems are provided. The restraint systems can include: a passenger seat supported by a frame; a restraint bar pivotably attached to the frame; and at least one piston operably engaged between the restraint bar and the frame. Restraint system pistons are provided. The pistons can include: a central chamber housing a piston head and rod; a fluid reservoir in fluid communication with the central chamber; and at least one electromechanical valve operable between an open and a closed position. Methods for restraining a passenger within a seat are also provided. Manually operable piston assemblies are provided that can include a piston head within a cylinder, the piston head separating fluid in the cylinder to define rod-side fluid and head-side fluid. The piston assembly can be configured to operate in at least six positions, including but not limited to a first position of locking retract static; a second position of locking retract extend flow; a third position of locking retract flow; a fourth position of locking extend static; a fifth position of locking extend retract flow; and a sixth position of locking extend flow. Manually operable piston assemblies are also provided that can include a piston head within a cylinder, with the piston head separating fluid in the cylinder to define rod-side fluid and head-side fluid. The manually operable piston assembly can further be configured to operate in at least six positions that include a first position of locking extend static; a second position of extend movement flow; a third position of manual override retract flow; a fourth position of manual override extend flow; a fifth position of locking retract static; and a sixth position of retract movement flow. Methods for operating a manually operable piston are also provided. The methods can include applying pressure to retract the piston rod and allow head-side fluid to pass through piston head passageway and mix with rod-side fluid. Methods for operating a manually operable piston can also include applying pressure to extend or retract the piston rod and allow head-side fluid to pass through at least one valve and mix with rod-side fluid.