Other Pinwheel

Felix Arithmometer

Felix Russian Mechanical Pinwheel Calculator

Serial No. (Russian P)61871

Date: 1920-1970 (Anybody’s guess!)

Capacity: 9x8x13

Price paid: £10

This machine was made in the Soviet Union. Compared with ‘Western’ machines, the machine is rather crudely made.  It lacks some of the refinements of most other machines – in particular, it lacks the mechanism which ensures that complete turns of the crank are made.  However, this shouldn’t be an issue in the hands of a competent operator.

It is difficult to date these machines because there isn’t much information available, and machines stayed in production for decades without significant changes.  For example, butterflies were still used to reset the registers until the end of production in the early 1970s, whereas most other manufacturers had replaced the butterflies with conventional cranks before 1930.

The machine, such as it is, works well.  I also believe it originally to be painted turquoise, judging by what can be seen when the cover is removed.

Muldivo Mentor (Re-badged Walther WSR160)

Muldivo Mentor (Walther WSR160) Mechanical Pinwheel Calculator

Serial No. 216154

Date: 1960s

Capacity: 10x8x16

Price paid (including postage): £9.95

The Muldivo Mentor is a Walther WSR160 with a Muldivo badge on it.  Muldivo was the British importer and seller of these machines.  In the mid to late 1960s, it seems that there was a scheme to introduce calculators into schools, and many manufacturers offered discounts to educational authorities.  Just in case you didn’t realise it, the Walther who manufactured these machines is the same Walther that manufactures handguns.

The machine used to work well – except………I used to have two of these.  So I kept the best looking one and sold the other. No sooner had the other machine been sold, the register resetting mechanism broke on this one.

The user guide for this machine can be found here.

Busicom HL-21

Busicom HL-21 Japanese Mechanical Pinwheel Calculator Nippon Calculating Machine Corporation

Serial No. 324555

Date: 1966-1970

Capacity: 10x11x21

Price paid (including postage): £16.80

Another machine with an educational background, it has a number of decals identifying the machine as the property of Croydon Education Committee.  This is a lovely machine to operate.  It also has the largest capacity of any of the machines in my collection, and is the only machine where the largest possible number in the input register can be squared and will fit in the result register.  A disadvantage of fitting all of these numbers into a relatively compact machine is that the numbers are a bit small – the pinwheels are on a 5mm spacing rather than the 7mm of the Odhners.

This machine would have cost £60 in 1966.

One curious connection between this machine and modern PCs is that Busicom entered into a contract with Intel (then unknown) in order to develop a chip set for a forthcoming electronic calculator.  The product of the collaboration was the 4004 micro-processor from which the entire family of Intel micro-processors can trace their ancestry.

The operator’s guide for this machine can be found here.

Brunsviga 13RK

Brunsviga RK13 Mechanical Calculator

Serial No. 13-63530

Capacity: 10x8x13

Date: 1950s

Price paid (including postage): £40 with the Facit CM2-16

Now this is more like it.  Brunsvigas have just gone up in my estimation.  This is a solidly construction lump with a convenient carrying handle on the side.  It has all of the usual refinements such as a Control Register, Tens Carry on the revolution counter, and Back Transfer.  The switch on the right front of the machine selects the clearing mode.  In its upper position, the top lever on the right clears both the revolution counter and the input register, and the middel lever on the right clears everything.  In its lower position, the top lever clears only the revolution counter, and the middle lever clears the revolution counter and result register (accumulator).  All of the registers can be cleared individually with the switch in the lower position.

Back transfer is effected by pulling the lever on the left towards you, clearing the input register.  If the lever is pulled further against a spring and held there, clearing the accumulator with the bottom lever on the right transfers its contents to the input register.