12 1/2”’ | Automatic | Swiss Lever | Indirect Sweeping Seconds | Date |

Remarks:

• Pellaton automatic, winding in both directions
• Two excenters on balance cock for regulator and stud carrier
• Movement family:
  • IWC 851: 12 3/4”’, 18,000 bph, height 5.45 mm, lift angle 54°, no date
  • IWC 852: 12 3/4”’, 19,800 bph, height 5.60 mm, lift angle 54°, no date
  • IWC 8521: 12 3/4”’, 19,800 bph, height 6.40 mm, lift angle 54°, date
  • IWC 853: 12 3/4”’, 19,800 bph, height 5.60 mm, lift angle 48°, no date
  • IWC 8531: 12 3/4”’, 19,800 bph, height 5.60 mm, lift angle 48°, date
  • IWC 854: 12 1/2”’, 19,800 bph, height 4.85 mm, lift angle 48°, no date
  • IWC 8541: 12 1/2”’, 19,800 bph, height 5.90 mm, lift angle 48°, date
  • IWC 854 B: 12 1/2”’, 19,800 bph, height 4.85 mm, lift angle 48°, no date, IWC type collet on balance staff replaced with Greiner type collet
  • IWC 8541 B: 12 1/2”’, 19,800 bph, height 5.90 mm, lift angle 48°, date, IWC type collet on balance staff replaced with Greiner type collet

• Listing ID: 20835
• Manufacturer / Brand: IWC
• Caliber: 8541B / 8541 B
• Size in French Lignes: 12 1/2'''
• Size range mm largest diameter: 22 - 31 mm
• Shape: Round
• Winding: Automatic
• Hands Setting: Crown
• Seconds Hand: Sweeping seconds (central seconds)
• Escapement: Lever (Swiss, English, Glashütte)
• Date, Day, Month...: Date
• Jewels: 25
• Setting Lever Screw/Pin Position: Right
• Balance Position: Bottom (120 - 240°)
• Shock Protection: Incabloc
• Beats per hour: 19,800
• Balance Type: Glucydur with Breguet hairspring and adjustment screws on balance spokes
• Power Reserve: 42 hours
• Production Period: 1970 - 1974 (8541 and 8541B)
• Country: Switzerland
• Identification: Rotor marked with INTERNATIONAL WATCH Co., base plate with C. 8541B. Original datasheet available.
• Contributor ©: Uhrforum.de member Badener (Andreas Kelz)