Roller gates are vertical lift gates with a series of rollers or wheels located along each side of the leaf. The rollers transfer hydraulic load from the gate to the roller tracks mounted in the guide slots on each side of the gate opening. The wheels minimize friction forces when raising and lowering the gate which in turn reduces the load on the gate operating system. Roller Gates are typically used where opening sizes are too large to efficiently use slide gates or for applications where gravity closure is a requirement. They are usually hydraulically operated to accommodate gravity closure but can also be operated electrically using either an electric actuator or wire rope drum hoist.