An apparatus for driving a valve pin in an injection molding system, comprising: an actuator comprised of a housing having a fluid sealed master chamber having a longitudinal axis and being formed within the housing, the actuator including a piston disposed within the master chamber, the piston having a circumferential surface complementary to an interior surface of the master chamber, the piston being slidable upstream and downstream along an axial path of travel within the master chamber wherein a seal surface is disposed on the circumferential surface of the piston that engages against and forms a fluid seal with a selected axial length of the complementary interior surface of the master chamber, the fluid seal forming opposing upstream and downstream fluid drive chambers (30u, 30d) disposed on opposing upstream and downstream ends of the piston within the master chamber, the path of travel of the piston extending between a fully upstream position and a fully downstream position, wherein upstream (50, 52) and downstream (60, 62) fluid delivery ports are formed within the housing of the actuator, the upstream (50, 52) fluid delivery port communicating with the upstream fluid drive chamber and the downstream port (60, 62) communicating with the downstream fluid drive chamber to reciprocally deliver drive fluid under one or more preselected pressures into the upstream and downstream chambers (30u, 30d) to reciprocally drive the piston between the fully upstream and downstream positions, ▪wherein a bleed device comprised of a single port formed and disposed within the housing so as to extend through the interior wall at an axial position along the path of travel of the piston wherein the single port communicates with the upstream fluid drive chamber and is sealed off from the downstream fluid drive chamber when the piston is disposed within a first selected portion of the path of travel and wherein the single port communicates with the downstream fluid drive chamber and is sealed off from the upstream fluid drive chamber when the piston is disposed within a second selected portion of the path of travel, wherein the single port is formed within the housing at an axial position along the axis of the master chamber such that either: an upstream axial end of the single port coincides with or overlaps with a downstream axial end of the seal surface when the piston is in the fully upstream position, or, a downstream axial end of the single port coincides with or overlaps with an upstream axial end of the seal surface when the piston is in the fully downstream position. an actuator comprised of a housing having a fluid sealed master chamber having a longitudinal axis and being formed within the housing, the actuator including a piston disposed within the master chamber, the piston having a circumferential surface complementary to an interior surface of the master chamber, the piston being slidable upstream and downstream along an axial path of travel within the master chamber wherein a seal surface is disposed on the circumferential surface of the piston that engages against and forms a fluid seal with a selected axial length of the complementary interior surface of the master chamber, the fluid seal forming opposing upstream and downstream fluid drive chambers (30u, 30d) disposed on opposing upstream and downstream ends of the piston within the master chamber, the path of travel of the piston extending between a fully upstream position and a fully downstream position, wherein upstream (50, 52) and downstream (60, 62) fluid delivery ports are formed within the housing of the actuator, the upstream (50, 52) fluid delivery port communicating with the upstream fluid drive chamber and the downstream port (60, 62) communicating with the downstream fluid drive chamber to reciprocally deliver drive fluid under one or more preselected pressures into the upstream and downstream chambers (30u, 30d) to reciprocally drive the piston between the fully upstream and downstream positions, ▪wherein a bleed device comprised of a single port formed and disposed within the housing so as to extend through the interior wall at an axial position along the path of travel of the piston wherein the single port communicates with the upstream fluid drive chamber and is sealed off from the downstream fluid drive chamber when the piston is disposed within a first selected portion of the path of travel and wherein the single port communicates with the downstream fluid drive chamber and is sealed off from the upstream fluid drive chamber when the piston is disposed within a second selected portion of the path of travel, wherein the single port is formed within the housing at an axial position along the axis of the master chamber such that either: an upstream axial end of the single port coincides with or overlaps with a downstream axial end of the seal surface when the piston is in the fully upstream position, or, a downstream axial end of the single port coincides with or overlaps with an upstream axial end of the seal surface when the piston is in the fully downstream position. an upstream axial end of the single port coincides with or overlaps with a downstream axial end of the seal surface when the piston is in the fully upstream position, or, a downstream axial end of the single port coincides with or overlaps with an upstream axial end of the seal surface when the piston is in the fully downstream position.