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Cable Anchor Damper Installation
BATTERY POSITIONER

Aviation Boatswains Mate E - Aviation theories and other practices
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Upon engagement of the deck pendant by the aircraft, the engine crosshead is accelerated toward the fixed sheaves. This movement forces the ram into the arresting engine cylinder, increasing the fluid pressure in both the engine cylinder and the operating head of each cable anchor damper. See figure 3-21. Because   of   the   acceleration   rate   of   the   engine crosshead,   the   tension   in   the   purchase   cable   (2) between   the   engine   sheaves   and   the   cable   anchor dampers decreases momentarily. The instant the tensile force  in  the  cable  becomes  less  than  the  force  on  the operating piston (4), fluid pressure moves the operating piston away from its BATTERY position until all slack is removed and the cable tension is again greater than the fluid pressure force acting on the operating piston. The  flow  control  valve  is  a  clapper-type  check valve that allows free flow of the fluid one way and a restricted  flow  in  the  opposite  direction.  The  engine fluid has free flow through the flow control valve (1) to the operating end of each cable anchor damper. When the  tension  of  the  purchase  cable  is  transmitted  to  the cable anchor ends, the fluid pressure on the operating pistons  is  overcome  by  this  cable  tension,  and  the operating  pistons  are  pulled  back  toward  BATTERY position. Resistance to their return is furnished by the engine  fluid  pressure  and  the  controlled  flow  of  fluid through  the  flow  control  valves  back  to  the  engine cylinder. CUSHIONING PISTON The  sole  function  of  the  cushioning  piston  is  to prevent  the  operating  piston  from  slamming  into  the opposite  end  of  the  cable  anchor  damper  assembly  if the  purchase  cable  should  break  or  in  the  event  of  an extreme   off-center   landing.   In   either   situation,   the operating piston accelerates away from its BATTERY position and rams the cushioning piston. 3-23 TO ARRESTING ENGINE HYDRAULIC CYLINDER TO ACCUMULATOR HYDRAULIC SYSTEM 2 3 4 5 6 6 5 4 1 1 RETRACTING VALVE TO ACCUMULATOR HYDRAULIC SYSTEM 3 2 TO 3-WAY AIR VALVE 1. FLOW CONTROL VALVE 2. PURCHASE CABLE 3. OPERATING HEAD 4. OPERATING PISTON 5. CYLINDER 6. CUSHIONING PISTON ABEf0321 Figure 3-21.—Cable anchor damper fluid flow (arrestment).







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