A rotary valve actuator, comprising: a housing containing a first piston (306, 406) and a second piston opposite the first piston; an inner chamber defined in the housing between the first piston and the second piston, wherein the pistons (304, 306) are to move in opposite directions to rotate a shaft of the rotary valve actuator; and a damping apparatus operatively arranged to slow the movement of the pistons (304, 306) over only a portion of a stroke of the rotary valve actuator; characterized in that: the housing includes: a first port and a second port in fluid communication with the inner chamber; and in that the damping apparatus comprises: a first fluid circuit and a second fluid circuit, the first fluid circuit including a first fluid pathway fluidly coupled to the inner chamber via the first port and the second fluid circuit including a second fluid pathway fluidly coupled to the inner chamber via the second port; and a blocking element operatively coupled to the first piston, wherein the first piston causes the blocking element to move between a first position to enable fluid flow between the inner chamber and the first port and a second position to substantially restrict fluid flow between the inner chamber and the first port over the portion of the stroke of the rotary valve actuator during which the inner chamber is exhausted to a vent; and in that the second fluid circuit includes a fluid flow restrictor so that fluid flow through the second fluid pathway, when the blocking element is in the second position, is less than the fluid flow between the inner chamber and the first port when the blocking element is in the first position, such that when the blocking element is in the first position, the fluid in the inner chamber exhausts primarily through the first fluid pathway because of the increased flow resistance provided by the fluid flow restrictor and when the blocking element is in the second position, the fluid in the inner chamber is directed to exhaust primarily through the second port and the second fluid pathway. a housing containing a first piston (306, 406) and a second piston opposite the first piston; an inner chamber defined in the housing between the first piston and the second piston, wherein the pistons (304, 306) are to move in opposite directions to rotate a shaft of the rotary valve actuator; and a damping apparatus operatively arranged to slow the movement of the pistons (304, 306) over only a portion of a stroke of the rotary valve actuator; characterized in that: the housing includes: a first port and a second port in fluid communication with the inner chamber; and in that the damping apparatus comprises: a first fluid circuit and a second fluid circuit, the first fluid circuit including a first fluid pathway fluidly coupled to the inner chamber via the first port and the second fluid circuit including a second fluid pathway fluidly coupled to the inner chamber via the second port; and a blocking element operatively coupled to the first piston, wherein the first piston causes the blocking element to move between a first position to enable fluid flow between the inner chamber and the first port and a second position to substantially restrict fluid flow between the inner chamber and the first port over the portion of the stroke of the rotary valve actuator during which the inner chamber is exhausted to a vent; and in that the second fluid circuit includes a fluid flow restrictor so that fluid flow through the second fluid pathway, when the blocking element is in the second position, is less than the fluid flow between the inner chamber and the first port when the blocking element is in the first position, such that when the blocking element is in the first position, the fluid in the inner chamber exhausts primarily through the first fluid pathway because of the increased flow resistance provided by the fluid flow restrictor and when the blocking element is in the second position, the fluid in the inner chamber is directed to exhaust primarily through the second port and the second fluid pathway. a first fluid circuit and a second fluid circuit, the first fluid circuit including a first fluid pathway fluidly coupled to the inner chamber via the first port and the second fluid circuit including a second fluid pathway fluidly coupled to the inner chamber via the second port; and a blocking element operatively coupled to the first piston, wherein the first piston causes the blocking element to move between a first position to enable fluid flow between the inner chamber and the first port and a second position to substantially restrict fluid flow between the inner chamber and the first port over the portion of the stroke of the rotary valve actuator during which the inner chamber is exhausted to a vent; and in that the second fluid circuit includes a fluid flow restrictor so that fluid flow through the second fluid pathway, when the blocking element is in the second position, is less than the fluid flow between the inner chamber and the first port when the blocking element is in the first position, such that when the blocking element is in the first position, the fluid in the inner chamber exhausts primarily through the first fluid pathway because of the increased flow resistance provided by the fluid flow restrictor and when the blocking element is in the second position, the fluid in the inner chamber is directed to exhaust primarily through the second port and the second fluid pathway.