Vacuum cleaning head

A vacuum cleaning head comprising:

• a housing having a suction opening for admitting a first air flow to the head;
• an agitator for agitating a surface to be cleaned, the agitator being rotatably mounted in the housing;
• an air turbine assembly comprising an impeller for driving the agitator;
• a turbine air inlet for admitting a second air flow to the turbine assembly;
• a duct for receiving the first air flow from the housing and the second air flow from the turbine assembly;
• and:
• a control assembly for controlling the second air flow to the turbine assembly to inhibit rotation of the impeller, the control assembly comprising:
• a closure member moveable between an open position and a closed position for substantially closing the turbine air inlet;
• a pressure chamber connected to the closure member, the pressure chamber having an interior volume in fluid communication with the duct and which is variable in response to a pressure difference between the interior volume and ambient air between an expanded configuration in which the closure member is in the open position and a contracted configuration in which the closure member is in the closed position;
• and
• a control mechanism having a first state for preventing the pressure chamber from adopting the contracted configuration, and a second state for allowing the pressure chamber to adopt the contracted configuration, the control mechanism being arranged to change between the first and second states in response to an increase in the interior volume of the pressure chamber.