Marchant Calculating Machine Company

Marchant Calculating Machine Company

Company type	Private
Industry	Mechanical calculators, Electromechanical calculators
Founded	1911
Founder	Rodney Marchant, Alfred Marchant
Defunct	1958
Fate	Acquired by Smith Corona
Headquarters	Oakland, California , United States
Products	Mechanical calculators, Electromechanical calculators

The Marchant Calculating Machine Company was established in 1911 by Rodney and Alfred Marchant in Oakland, California. Initially, the firm manufactured mechanical calculators, later transitioning to electromechanical models noted for their dependability. The earliest devices bore a strong resemblance to the Odhner arithmometer. In 1918, employee Carl Friden developed a successful new model and served as chief designer until his departure in 1934 to found a separate enterprise. In 1958, the company was acquired by the Smith Corona typewriter manufacturer as part of a diversification effort. Under SCM's ownership, the electronic SCM Cogito 240SR calculator, designed by Stan Frankel, was launched in 1965. Nevertheless, the emergence of low-cost electronic calculators gradually diminished their market share, and by the mid-1980s, SCM’s typewriter segment also suffered due to competition from personal computers functioning as word processors.

Calculator design

Marchant's later Silent Speed Proportional Gears models ranked among the fastest mechanical calculators available, capable of performing at 1,300 cycles per minute. Their distinctive mechanism featured result dials that rotated at speeds proportional to the digit input—where entering '1' resulted in slow movement and '9' triggered the fastest speed—contrasting with other calculators that moved dials at a uniform speed for varying time intervals. This proportional speed approach was uncommon; only the European Mercedes Euklid employed a somewhat comparable but simpler technique.

The transmission of carries to higher order digits utilized a 10:1 gear ratio akin to conventional watthour-meter dials, likely unique within calculator designs. During multiplication operations, much of the internal mechanism operated at a steady speed. Whereas competing calculators initiated and halted rapidly at a single speed, Marchant’s design featured each column functioning as a nine-speed pre-selector transmission incorporating several hundred gears.

Carry operations from lower-order digits were managed via one planetary differential per dial. Depressing the + bar enabled observation of higher-order dials moving proportionally. Unlike watthour meter dials—which do not precisely align when adjacent dials are between digits—Marchant’s dials incorporated constant-lead ("snail") cams alongside a secondary spur-gear differential per dial to ensure exact alignment.

Some serviced units exhibited minor misalignments in dial positioning attributed to gear meshing inaccuracies. Compared to competitors such as the simpler Friden STW, Marchant’s mechanism was notably intricate, containing approximately 25 layers of levers and linkages beneath the keyboard and three driveshafts spanning the mechanism—most other calculators featured only one.

For fully automatic division, typical mechanical calculators subtracted repeatedly until an overdraft occurred and then added once to correct the result. Marchant implemented a series of analog comparators to predict overdrafts ahead of time and prepare subsequent quotient digits, thereby improving both speed and precision.

In summary, Marchant’s advanced internal engineering delivered considerable performance advantages over other calculators produced during the same period.

External links

• SCM Marchant Cogito 240SR calculator
• Stanley Frankel, Recirculating Memory Timing, filed February 1964, issued June 1970
• Marchant Figurematic calculator Technical description with detailed photographs by an engineer