US 6812 Bombe Report

Introduction

The following is a brief description or the operations of the 6812th Signal Security Detachment in the European Theater of Operations from 1 February 1944 to 7 May 1945. It was necessary to completely train the operators, engineers and technicians before the work [on Turing/Welchman‘s Bombe] could be begun. The contents of the following pages had to be thoroughly understood by each man. From the beginning of operations to VE Day the 6812th Signal Security Detachment found the solutions to a total of 425 German Enigma Key.

Summary (Chapters)

  1. Theory of Decoding and Decoding Machines.
  2. Procedure Used in Machine Decoding.
  3. Description and Characteristics of Bombe and Checking Machine.
  4. Decoding Machine Circuits
  5. Job Meanings.
  6. Explanation of Photographs.

Chapter III. Description and Characteristics of Bombe and Checking Machine

General Description..........................................Page 59
Weight.......................................................Page 59
Power Consumption............................................Page 59
Operating Speed..............................................Page 59
Installation & Preparation for Use...........................Page 59
Relocation of Motor & Control Power Switch...................Page 59
Running Test Menus...........................................Page 59
Attaching Drums..............................................Page 59
Figure 44-Front of Bombe.....................................Page 60
Figure 45-Rear of Bombe......................................Page 61
Test Menu I (No need for the diagonal board).................Page 62
Test Menu II.................................................Page 62
Test Menu III................................................Page 63
Test Menu IV.................................................Page 63
Test Menu IVA (double imput Menu)............................Page 64
Test Menu V (Menu with a isolated chain).....................Page 65
Test Menu Va (Menu with a isolated chain)....................Page 65
Test Menu VI (Menu with 2 chains and 2 inputs)...............Page 66
Test Menu VII (throw on menu)................................Page 66
Figure 51 - Drum used on Bombe...............................Page 67
Plugging-Up Bombe............................................Page 68
Setting Switches.............................................Page 69
Bombe Running & Sensing-Electrical Control Circuit...........Page 69
Mechanism of Bombe...........................................Page 71

Reference

This Report was entered and formatted by Tony Sale.