Welcome to the fourth spotlight of the Lilly Library’s Mechanical Puzzle blog series, written by Andrew Rhoda, the Lilly Library’s Curator of Puzzles!
What are Disengagement Puzzles?
Disentanglement puzzles are like interlocking puzzles in that the goal is to both take apart the puzzle and put it back together. However, a notable difference is that with disentanglement puzzles you remove only a part of the puzzle, usually a ring or a piece of string, rather than completely taking the puzzle apart. Disentanglement puzzles also often feature a smaller number of pieces in comparison to interlocking puzzles.
Examples of Disengagement Puzzles
Some puzzles in the “cast metal” sub-category can have as few as two pieces. There are a variety of forms these “cast metal” disentanglement puzzles can take, but a popular form that they take are the “Nails” or “Bent Nails” puzzle. Walter Jenkins patented this puzzle in 1910 in the United States; however, it potentially dates back as far as the 17th century (Slocum et al 1986, 97). The goal of the puzzle is to slide the two nails apart. This puzzle was a common puzzle used in advertising, using the heads of the nails to display logos or other information (Slocum et al. 1986, 97).
Another well-known puzzle in this category commonly goes by the title of either “Baguenaudier” or the “Chinese Rings.” As you can see from the example here, the puzzle consists of metal rings connected to a piece at the bottom by wires. A loop of metal wire, or occasionally other material, holds the rings, with the rings passing through the center space of the loop to remove them. This process is complicated by the fact that the wires connecting the rings to the piece at the bottom of the puzzle will not allow you to take the rings off in order. Because of that, a specific pattern must be used to remove the rings. This pattern is repeated in a sequence until all the rings are removed and replaced. With the solution involving both disentangling rings from the loop and using a sequence of moves to do so, this puzzle fits in both this category and the next, sequential movement puzzles. Which category do you put the puzzle in then?
Jerry Slocum contended with the same question about the Chinese Rings. In Puzzles Old and New he and his co-authors write, “Most often it is categorized as a disentanglement wire puzzle, specially as far as the classic Chinese Rings is concerned. However, the solution of this puzzle involves a sequence of moves which is very similar to that used when solving the Tower of Hanoi – which is a sequential movement puzzle” (Slocum et al 1986, 105). In the end, rather than making his categories exclusive, he decided that if a solution for a puzzle fell into more than one category, he would include the puzzle in all the relevant categories.
Another example, and one intended for a practical purpose, are “Horse Hobbles.” When horses were a primary form of transportation, these hobbles served as a security function. At night, the rider would place the set of hobbles on the front hooves of a horse, the hobbles allowing the horse some freedom of movement while not allowing them to run (Slocum et al 1986, 97). As with other practical puzzles, once the security function of the puzzle became obsolete, it became an interesting problem for entertainment.
The Hanayama Company produces cast metal puzzles from contemporary puzzle designers as part of their Huzzle Cast Puzzle Series. The series features smaller metal puzzles where the goal is to disentangle the pieces of the puzzle, although the series does include puzzles from other categories. The Hanayama Company started in 1933, producing puzzles like the Lucky Puzzle, a put-together puzzle (Hanayama Toys, n.d.). The Lucky Puzzle was a republication of the Richter Company’s Kreuzzerbrecher (Cross Breaker) puzzle, first published by Richter in 1891 (Slocum and Botermans 1994, 10). As Slocum and Botermans describe the puzzle in The Book of Ingenious and Diabolical Puzzles, as follows, “It has seven wooden pieces that are used to solve sixty-eight original Japanese problems such as Samurai, Angry Cat, and Submarine” (Slocum and Botermans 1994, 10). These days, the main line of puzzles for Hanayama are the Huzzle Cast Puzzles, which is a series that the company distributes around the world and is familiar to puzzle enthusiasts around the world (Hanayama Toys, n.d).
Up to this point, I have focused on disentanglement puzzles made of metal, either cast metal or metal wire. However, other sub-categories feature other materials than metal, such as “string disentanglement” puzzles. As the name suggests, the element that one removes and replaces from the puzzle is a loop of string, usually made from twine, yarn, or sometimes leather.
String disentanglement puzzles are another type of puzzle that included advertisements to creatively publicize products at the turn of the 20th century (Slocum and Botermans 1992, 81). Generally, these advertising cards would include information about products or a store’s location along with other elements to attract a customer’s interest. One way that they captured a person’s interest was through some form of puzzle. As Slocum and Botermans write in the New Book of Puzzles, “The idea was that if a customer had to spend time solving a certain product puzzle, you could be sure that he or she would remember that particular brand” (Slocum and Botermans 1992, 81).
While common puzzles were hidden image pictures or rebuses, some advertisers also included mechanical puzzles in their repertoire of puzzle cards. In the image included here are examples of string disentanglement puzzle cards used to advertise products as diverse as breakfast food and musical instruments.
If you are interested in seeing more disentanglement puzzles in the Slocum Puzzle Collection you can learn more at https://libraries.indiana.edu/lilly-library/mechanical-puzzles, or by attending the Friday Puzzle Tour held from 1:00pm to 2:00pm in the Slocum Room.
About the author: Andrew Rhoda is the Curator of Puzzles at the Lilly Library, where he oversees the 35,000 mechanical puzzles in the Jerry Slocum Mechanical Puzzle Collection, in addition to the Slocum book and manuscript collections. He hosts classes from across disciplines who visit the collection, and he has presented on mechanical puzzles and the collection at puzzle events here in Bloomington and around the world.
Bibliography
Hanayama Toys. n.d. “About – Hanayama Toys | Just for Fun.” Hanayama Co. Ltd. Accessed November 19, 2025. https://hanayama-toys.com/about.
Slocum, Jerry. and Jack Botermans, 1992. New Book of Puzzles. W. H. Freeman and Company.
Slocum, Jerry. and Jack Botermans. 1994. The Book of Ingenious & Diabolical Puzzles. Times Books.
Slocum, Jerry and Jack Botermans, Carla von Splunteren, and Tony Burrett. 1986. Puzzles Old and New: How to Make and Solve Them. Plenary Publications International (Europe).
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