Thrust reversal - Cold stream reverser system

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Thrust reversal - Bucket target system

Cold stream reverser system 

Fig. 15-4 A typical fan cold stream thrust reversal system.

15. The cold stream reverser system (fig. 15-4) can be actuated by an air motor, the output of which is converted to mechanical movement by a series of flexible drives, gearboxes and screwjacks, or by a system incorporating hydraulic rams.
16. When the engine is operating in forward thrust, the cold stream final nozzle is 'open' because the cascade vanes are internally covered by the blocker doors  (flaps)  and  externally  by  the  movable (translating) cowl; the latter item also serves to reduce drag.
17. On selection of reverse thrust, the actuation system moves the translating cowl rearwards and at the same time folds the blocker doors to blank off the cold stream final nozzle, thus diverting the airflow through the cascade vanes.