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Marchant Figurematic - Technical Description

These pages give an illustrated technical description of the internal mechanism and the principles of operation of the Marchant "Figurematic" mechanical calculator.

The machines built by the Marchant Calculator Company during its sixty-year history can be divided into three broad families, according to the design of their internal mechanism:

• The first, dating from the Company's formation in 1911, was a lever-set pin-wheel design similar to the European Odhner and Brunsviga machines.
  
  
• The second, introduced in the early 1920s, was a modified pinwheel machine with a keyboard setting mechanism. This design was further developed during the 1920s and 30s, leading eventually to electrically-operated machines with semi-automatic multiplication and division.
  
  
• A radically different mechanism based on proportional and differential gearing was introduced with the "Silent Speed" machines in 1933. The name was appropriate, as these machines were significantly quieter and more than twice as fast as most of their competitors. Ongoing refinements to the Silent Speed family led eventually to the Figuremaster and Figurematic machines from the late 1940s, and the Transflo and Deci-Magic from the 1950s. The Marchant family established a solid reputation for speed and reliability, and continued in production in various forms until the business closed in the early 1970s.

The notes and photographs in these pages are based on a Marchant "Figurematic" Model 10DRX from the 1950s. They were prepared during the overhaul of machine number 412562 during 2004. The descriptions are based primarily on my own observations and interpretations, supplemented by reference to reprints of Marchant drawings and training materials. A subsequent review of Marchant patent information has clarified some of the subtleties of the mechanism, but has not required any major alterations to the text.

These notes are intended as a general guide to the construction and the principles of operation of the Figurematic mechanism. They do not attempt to explain all of the internal details, nor do they provide detailed instructions for disassembly or repair. While I believe my descriptions to be substantially correct, I do not guarantee that they are accurate, complete, or applicable to any other machine. Please do not dismantle a Marchant in the expectation that these notes alone will get it back together!

I would welcome advice of any corrections, or suggestions for improvement.

Contents

1. Introduction (this page)
2. Overview
3. The keyboard
4. The actuator unit
5. The selector unit
6. The control unit
7. The drive train
8. The multiplier
9. The carriage
10. The counter register
11. The main register and carry mechanism
12. The carriage shift mechanism
13. The clearing mechanism
14. The division control mechanism
15. Description of operation
16. Marchant patents

Resources for Further Information

• Reprints of various Marchant instruction and technical manuals are available from Ernie Jorgensen's "Office Machine Americana" in Idaho, USA. The manual entitled "SCM Marchant Technical Training Centers - Supplemental Training Materials" is recommended as an adjunct to these notes. It contains very little text, but has detailed technical drawings of all of the major components and sub-assemblies of the late-model Figuremaster mechanism.
  
  
• Readers requiring greater detail than is presented here may wish to study the extensive list of patents that were issued for the Silent Speed and Figuremaster mechanisms. These provide a wealth of extremely detailed drawings and descriptions of operation of individual sections of the mechanism. The Figurematic Patents page gives further information, and highlights some of the more interesting documents.