| 摘要 |
An injection device (13) for liquid bitumen has an outlet orifice (14) in a spray applicator (11), a closure member (16) fitted with a control rod (17) being able to open or close this orifice. This rod is driven by a pneumatic driving cylinder (18) which includes a cylindrical space (20) subdivided by an internal movable piston (21) into two compartments (22, 23) located on either side of the piston. A control device (24) is assigned to the driving cylinder, this device enabling pressurised fluid to be supplied to one of the compartments, and the corresponding surface of the piston, for the purpose of actuating the closure member. The driving cylinder and the corresponding control device are combined into a unit (25) which can be fixed to the spray applicator. The casing (19) of the driving cylinder includes control conduits (30, 31) and electromagnetic-control valves (32, 33) which control the control conduits. The latter open out into the compartments located on either side of the piston. <IMAGE>
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