A vehicle hood comprises a frame which may be extended by a pair of hydraulically operable rams (1 and 2) from stowed to an extended position and tensioned by a pair of hydraulically operable rams (3 and 4). The rams are supplied in operation with hydraulic fluid by means of a pump (6) through a hydraulic circuit comprising a solenoid operable valve (13) in parallel with a variable restrictor (14). As the hood is extended gravity tends to take over. At that point a microswitch (15) is activated by the hood to close valve (13) thereby lowering the hydraulic fluid flow rate and obviating crashdown of the food.
