barricade  webbing  assembly,  the  barricade  power package,  and  the  barricade  stanchion  assemblies  in this  chapter. ARRESTING  ENGINE The  Mk  7  arresting  engine  is  a  hydropneumatic system  composed  basically  of  the  engine  structure, a cylinder and ram assembly, the crosshead and fixed  sheaves, a   control   valve   system,   the accumulator  system,   auxiliary  air  flasks,  and  a sheave  and  cable  arrangement. Improvements are continuously being made to increase  the  capabilities  of  carrier-based  aircraft.  As the capabilities of the aircraft are increased, the weight and speed also increase. Therefore,   the equipment  used  to  recover  the  aircraft  aboard carriers  must  also  be  improved  to  keep  pace  with aircraft   advancement. Such  improvements  have brought  about  the  recovery  equipment  installed  on our carriers in the fleet today—the Mk 7 Mod 2 and Mod 3. Table 3-1 lists the leading particulars of the Mk 7 Mod 2 and Mod 3 recovery equipment. Table  3-1.—Leading  Particulars  of  Mk  7  Recovery  Equipment Mod  2 Mod  3 MAXIMUM  ENERGY  ABSORPTION: Service   stroke 38,000,000   ft-lb 47,500,000   ft-lb ENGINE  DRIVE  SYSTEM  CABLES: Breaking   strength/diameter Deck  pendant  (6  x  30  flattened  strand) 188,000  lb/1  3/8  in. 188,000  lb/1  3/8  in. Purchase  cable  (6  x  25  round  strand) 195,000  lb/1  7/16  in. 195,000 lb/1 7/1 6 in. Reeving  ratio 18 to 1 18 to 1 ARRESTING  ENGINE: Length 50 ft 50 ft Weight 37  tons 43  tons Engine fluid Ethylene  glycol Ethylene  glycol Engine  fluid  capacity  (without  cooler) 320  gal 380  gal Engine  fluid  capacity  (with  cooler) 500  gal 560  gal Ram  diameter 18.495  in. 20.000  in. Effective  ram  area 268.8  sq  in. 314.16  sq  in. Length of maxim urn stroke 186.00  in. 192 in. Length  of  service  stroke 171.00  in. 183 in. Crosshead   battery   position 1 to 7 in. 1 to 6 in. (distance  from  stop) Accumulator  operating  medium Ethylene  glycol/air Ethylene  glycol/air Maximum   pressure 650  psi 650  psi Initial working pressure 400  psi 400  psi Type  of  coolant Seawater Seawater Length of runout 310ft 340 ft 3-5