A hold open rod is configured to provide switched damping movement includes an inner tube assembly coupled to an outer tube assembly, the inner tube assembly movable within the outer tube assembly. The hold open rod also includes a damping mechanism configured to damp movement of the outer tube assembly with respect to the inner tube assembly.

The present disclosure includes a telescoping hold open rod which is controllably lockable and unlockable for use in holding a panel such as a nacelle open to provide a user access to an opening covered by the panel. The hold open rod is useful in allowing the rod to be unlocked and telescopically collapsed. The rod can be locked into a telescopically extended position to maintain the panel in an open position relative to the opening to facilitate access to the opening without the rod telescoping closed. A retention assembly includes structures and devices to maintain the rod in an open condition although subject to compressive loads.

A solar tracker system includes a support tube, a solar panel assembly connected to the support tube, and an active lock connected to the support tube. The active lock includes a housing defining a chamber and a seal. The seal prevents a flow of fluid through the chamber when the active lock is in a sealed state and allows the flow of fluid through the chamber when the active lock is in an unsealed state. The active lock further includes a locking system motor connected to the seal to transition the active lock between the sealed state and the unsealed state, a battery providing power to the locking system motor, and an antenna for receiving instructions controlling the locking system motor.