The book Sliding Piece Puzzles by L.E. (Edward) Hordern was published in 1986 by Oxford University Press as part of the Recreations in Mathematics series edited by David Singmaster. The book describes more than 270 sliding piece puzzles (also known as sliding block puzzles) and provides solutions. The Cleverwood website has an informative excerpt from a precursor work by Hordern.

In his book, Hordern states that all puzzles of this type have pieces that slide, without lifting or jumping, from one position to another, and a space into which to slide the pieces. You can try some sliding block puzzles on-line at Nick Baxter's site hosted by John Rausch. You can also play Java versions on-line at janko.at, a German site. Try the Bulbous Blob online at Puzzlebeast. See this article by Ed Pegg, Jr. on sliding-block puzzles for an excellent survey. Ed discusses the Quzzle (which can be emulated using the Dad's Puzzle pieces). See Taniguchi's Programs page for a solver program.

In Sliding Piece Puzzles, Hordern defines four categories: Sliding block puzzles (subgroups A through G) - in which each piece can move independently of the others Soko (warehouse) puzzles (H1-H10) - in which one piece must push all the others Railway shunting puzzles (J1-J13) - in which one or two pieces must push or pull all the others Sliding puzzles with plungers or levers - in which pieces move in groups

The first category is further subdivided into the following subgroups, which Hordern labels A through G: A1-A10 - Random arrangement sliding block puzzles B1-B60 - Sliding block puzzles with uniform pieces C1-C76 - Sliding block puzzles with rectangular pieces D1-D50 - Sliding block puzzles with non-convex pieces (i.e. L-shaped or T-shaped pieces) E1-E35 - Restricted-route sliding block puzzles (e.g. Perplexity and Rush Hour) F1-F13 - Sliding block puzzles with special shaped pieces or where rotation is allowed G1-G5 - Three-dimensional sliding block puzzles

In this section I cover examples of most of the above groups. I focus on those puzzles in my collection, and show a few others for reference. The Soko-type puzzles are typically presented as electronic games or computer software programs rather than physical mechanical puzzles, and I do not cover them. The book does not cover the last category (4), other than to show a color plate of some example puzzles, including The Ten Billion Barrel and Trillion, and is very light on (G). Three-dimensional sliding piece puzzles are a huge category and I cover them on my Rearrangement page.

In his 1942 book 100 Puzzles - How to Make and Solve Them, Anthony Filipiak describes ten "shifting block" puzzles, most of which are covered by Hordern: 19 Block - H.C71 9 Block - H.C19 Dad's Puzzle 5 Block - H.B1 - Sam Loyd's The Moving Day Puzzle 11 Block - H.C52 Bull's Eye (11 blocks) - H.B23 ZOT George Washington's Career (15 blocks) - H.C67 10 Block - H.C17 Schweig's Trans-Atlantic 15 Block or 1-2-3 - H.C72 Rectangle - H.D1-3 Ma's Puzzle 27 Block

It was eventually proved that half the random arrangements can be solved, while the other half are impossible. We now distinguish the solvable from the unsolvable arrangements by checking their "parity" - which amounts to the number of pairs which must be swapped to restore regular order. If the parity proves even, the position is solvable - if odd, unsolvable. This did not prevent people from claiming to have solved impossible arrangements. Most often their "solution" entailed some way of re-defining the goal state - for instance placing the empty space elsewhere than at the lower right, ordering the numbers in some way other than left to right in rows down the tray, or making use of a rotation of the tray itself (thusly leaving the figures not right-side up, or employing round tiles so as to be able to re-right them afterwards).

Jerry Slocum and Dic Sonneveld put out a book on the history of the 15 puzzle. In the book, they reveal that although Sam Loyd claimed and often got inappropriate credit for its invention, the actual inventor was Noyes Chapman, a postmaster in Canastota, New York, who applied for a patent in 1880. The patent was denied, perhaps because the 15 Puzzle was too similar to 207124 - Kinsey 1878, which specified the tongue-and-groove arrangement now commonly used for holding the tiles in the tray. Sam Loyd really shouldn't even be credited with popularizing the impossible challenge called "14-15" in which the starting position has only the 14 and 15 tiles swapped. The probable impossibility of that challenge was already appreciated back during the original craze. Since this position has odd parity, it cannot be solved. Loyd must have felt secure in offering a $1000 prize for a solution!

Hordern categorizes the Fifteen puzzle (along with the 14-15) as B10, rather than in the A group - probably because only a specific subset of starting positions is solvable. Hordern's first puzzle in the A group, A1, is RATE YOUR MIND PAL. It can always be solved, regardless of the initial position of the blocks. Bearing in mind the parity issue, can you figure out why?

A1 RATE YOUR MIND PAL Plas-Trix	A3 Franklyn's Tobacco Puzzle When solved, it reads "Smoke Franklyns Fine Shagg It Is Good."	U N I T E D           S T A T E S A4 United States I don't have it or a photo. Start with the blocks in random positions, finish as shown. Black squares are impassable.
A5 Question du Jour (aka La Grande Question or the Columbia Puzzle)	A6 Ten Little N****r Boys See U.S. patent 602735 - Donaldson 1898. Also see 437932 - McGrath 1890. (I don't have this.)	A7 Le Moulin Rouge
A9 Latin Square variants such as the Roalex Psycho Numbers (I don't have this.)	Safari Another Latin square.	A10 Four Square (aka Court Card by Fairylite) Objective is a Graeco-Latin Square. See U.S. patent 433444 - Brown 1890. (I don't have this.)

Bedstead     Table   Icebox   Sofa Bureau B1 The Moving Day Puzzle eq. to the 5 Block Puzzle in Filipiak Exchange the bedstead and icebox in the fewest moves. I don't know if this was ever produced as a physical puzzle - I don't have it and I don't have a photo, but it is easy to emulate (I made one from Lego) and I think it is a great little puzzle to try. See the Moving Day Puzzle in an online version of Sam Loyd's Cyclopedia at Ed Pegg's site. Play it online at janko.at or at Nick Baxter's site.	B5 (B4 thru B8) Eight Block Puzzle (various start and end conditions) A 3x3 grid with one space and eight uniform blocks. Many variations exist, including this Sun Face. Play B6, Dudeney's Letter Block, online at janko.at or Nick Baxter's site.	B9 The Flanders Wheel From Puzzles and Curious Problems by H. Dudeney ca.1917 I don't have it or a photo. Move the pieces along the lines from spot to spot starting with the arrangement shown, so FLANDERS can be read clockwise beginning with the F at 12 o'clock.
B10 The Fifteen Puzzle There have been countless variations produced, including an early wooden version from the Embossing Co. of NY, a nice metal version from Binary Arts and a cheap plastic smiley-face version. B11-B15 are variations, some to form magic squares rather than order the numbers.	This is an interesting version of the sliding block theme called Color Magic. I bought it at Games People Play. It is from the Metropolitan Museum of Art. Begin with primary colors. Slide the fifteen tinted translucent tiles in order to produce the secondary colors. The color of a tile combines with the color of the square printed beneath it on the base.	Janus - by Frank Potts (I don't have this.) The idea here is to solve a kind of 15 puzzle, but the twist is that each number is represented in stylized segmented form and has been decomposed into two sets of segments, each of which is on a separate transparent layer. Essentially you need to solve two 15 puzzles simultaneously so that the transparent tiles combine properly to re-form the numbers in order. Some thought went into how to best decompose the numbers into two separate layers, to allow one proper solution. Another twist is to present a 15-14 version that can be solved with a parity trick. Frank says he made only two to enter in the IPP 2005 design competition - the photo is from the design competition page on John Rausch's site. Play Janus online at Frank's website.
Kenreign Rain Coat New Puzzle Game	Prosperity Puzzle	The Improved 15 (Star) Puzzle
1   2 3 4 5 6 7 8 9   B17 The Fifteen Puzzle (variation from Wit Sharpeners 1944) I don't have it or a photo. Slide the numbers to create a magic square where all rows, columns, and the two main diagonals add to 15.	C A N A M A P A N A L   B18 Panama Canal I don't have it or a photo. Play it online at janko.at or at Nick Baxter's site.	B19,B20 Good Luck 1919 B19: Exchange rows 1 and 2 intact. B20: Move row 1 to bottom, all rows end intact.
B21 Capturing the Kaiser / Tit-Bits New Game 1914-18, 1930s I don't have it or a photo. Surround Kaiser Wilhelm, Von Tirpitz, the Crown Prince, and Count Zeppelin with soldiers. Could this be the elusive Tit-Bits Teaser No. 3?	B23 ZOT Skor-Mor B24 is a variant called "ZOX" where the T is replaced by an X. In ZOX, the Z and X must end up in the same relative positions as at the start. This will require some lateral thinking! B25 is a further variation, by N. Takashima.	B28 Dormitory Dash - Peterson Games 1975 (I don't have this.)
1 2 3                         4 5 6 B33 A Motor-Car Problem Dudeney 1903 I don't have it or a photo. Exchange 1/4, 2/5, 3/6. This is the "three-letter" version of B35.	B34 Switchit	B35 Work or Golf (aka A Motor Garage Puzzle) Play online at janko.at or at Nick Baxter's site. See B33,B34 for the "three-letter" version of this four-letter puzzle. B36 extends both words to five letters, and adds another "siding" space opposite the existing one.
2 3 4 5 6 7 8 9 1 B37 Nine Men in a Trench I don't have it or a photo. Play it online at janko.at or at Nick Baxter's site. B38 is a 1984 version from Hong Kong, where pieces 2-5 are one color, 6-9 a second color, and 1 a third color. You are to move 1 to the left side and swap the other two colored groups. The pic is from Martin Watson's collection. I don't have this.	B41 So Easy / Le Jeu des Quatre Coins
B42 L'Evasion Difficile (I have the plainer version.)	MM       MM L A D Y   M I N E   B43 Anagram Blocks From "Sam Loyd and His Puzzles" 1928. Rearrange the letters to spell "MAID ENLY" in two rows. I don't have it or a photo.	B44 Honor and Glory (Black and White) Play Black and White online at Nick Baxter's site.
B46-49 Nutzy Numbers (aka Tantalising 7, Nutty Numbers)	B50-59 The Time Puzzle by the Embossing Company of Albany NY. See patent 1989411 - 1935	B60 The New 15 Puzzle 1923

After the Fifteen Puzzle, the next two most-sold sliding piece puzzles are probably Dad's Puzzle(r), and the L'Ane Rouge design. Both have been extensively copied; the former used often for advertising, and the latter appearing in many modern versions.

Many different challenges can be attempted using the 4x5 tray and the following set of pieces:

• (2) 2x2 squares, mutually distinct
• (8) 1x1 squares
• (6) 1x2 rectangles

4x5 designs which require large numbers of moves to complete include Quzzle by Jim Lewis (84 moves), Quzzle-Killer by Bob Henderson and Gil Dogon (90 moves), and finally the Super-Century by Gil Dogon, which requires the largest number of moves (138) for a 4x5 tray using rectangular pieces.

1   2   3  A B 4 5 C1 U.S. Patent 516035 - H. Walton 1894 Exchange A and B. I don't have it or a photo.	C2 Get My Goat (Should have one rectangular piece in upper right, else it becomes B23.) U.S. Patent 1112746 - Wiley 1914 Play online at Nick Baxter's site.	C2 Katch the Kaiser
C3 Qwik-Sane	C4 Line Up the Quinties R. W. Fatiguant, 1934 Move the faces to form a line where the flowers are. Play it online at Nick Baxter's site.
C6 A Yank Thru the Lines 1942 WWII Slidem-Solitaire Puzzle Electric Corporation of America, Chicago	C7 Bombing Tokyo 1942 WWII Slidem-Solitaire Puzzle Electric Corporation of America, Chicago	C8 Tank Attack 1942 WWII Slidem-Solitaire Puzzle Electric Corporation of America, Chicago
1    A  2  3 4   5 7 6    8 9 C12 The Infant's Hospital Puzzle Chad Valley 1920 I don't have it or a photo. Move A to the bottom right. The black area is impassable. There is a 1x3 gap and a 1x1 gap.	C14 Moss' Puzzle See U.S. Patent 668386 - Frank E. Moss 1901 I don't have it or a photo - Hordern is unsure of whether this was ever produced. The sides labeled a,b,c, and d are different colors - rectangular pieces G,H,J, and I are correspondingly colored. Each starts across from its corresponding side and must end up as shown. The corner pieces C,D,E, and F are each bi-colored according to their home positions. They start out diagonally across from their homes. The two middle pieces L and N remain in the middle but their respective positions don't matter.	C17 The 10 Block Puzzle (Filipiak), aka Traffic Cop Tangle. Also appeared as Schweig's Transatlantic Puzzle. Play online at Nick Baxter's site. This puzzle was included in the "Party Puzzle Box Supreme" compendium from George Schweig & Son of Philadelphia PA.
C19 The Pennant Puzzle aka Dad's Puzzle(r) The Pennant Puzzle was copyrighted in 1909 by Lewis W. Hardy, who had filed another patent (1017752) in 1907 which was not granted until 1912. The Humdinger, Leech, Moving, and Eskimo Pie puzzles are the same. (I don't have the Pennant, Moving or Eskimo Pie versions. The Pennant, as baseball memorabilia, sold for $475! Thanks to Jan de Geus for pointing it out.) Play online at janko.at or Nick Baxter's site.
C20,21 Jusso Nine Block Puzzle
C27 L'Ane Rouge (The Red Donkey) Patented in England ( 411515) by J. H. Fleming in 1932. Modern versions include Tryne's Hako, Skor Mor's Ego Buster, Psychoteaze, Intreeg, Hix Brix, Mintman (Klotski), and the Chessmen. I have L'Ane Rouge, Haba's Quo Vadis, The VIP puzzle by Funtime Gifts Ltd., Hako, Hix Brix, Mintman, and the Chessmen. (Mintman solution here) Play online at janko.at or Nick Baxter's site.
C28 Let Me Through	C31-40 Khun Phan (or Khum Pan)	For some reason, Hordern omits Blockado. It is played on a 4x6 tray and is similar to C50,51, and 52. Acme Novelty Sales, 1928 Play it at janko.at or on Nick Baxter's site.
C56,57 The Flying Puzzle, Ching Foo, Tit-Bits Teaser #2, Silver Label, King Coal These use a 6x5 tray. U.S. Patent 1663568 - Schneider 1928 Move the plane to the bottom right corner - 55 moves.
C58 Tit-Bits Teaser #5 aka The Train Puzzle uses a second 2x2 square piece	C67 George Washington Puzzle	C72,73 The Sliding Block Puzzle by S.S. Adams Play online at Nick Baxter's site.

D1,2,3 Ma's Puzzle U.S. Patent 1633397 - Diamond 1927 Play online at janko.at or Nick Baxter's site.	D5 The Football Puzzle See U.S. Patent 771514 - Wehner 1904 Move the ball piece from the center to either top or bottom center.	D12-D23 The Traffic Jam Puzzle U.S. Patent 1683014 - Babcock 1928 aka Tit-Bits Teaser #4 (I don't have Tit-Bits Teaser #4.) Play online at janko.at or Nick Baxter's site.
D24-D43 Block 10 - Minoru Abe D24-D49 are designs by Minoru Abe. Try some at Nick Baxter's site.	This is The Slider Puzzle designed by Serhiy Grabarchuk and sold by Bits and Pieces. It is not in Hordern's book. Play online at Nick Baxter's site.	"Dog & Balls" (IPP27) designed by "Mine" (Mineyuki Uyematsu).

E2 The Four Frogs (aka Four Knights) I don't have it. This puzzle is a sliding version of a chess variant problem: on a 3x3 board, start with two white knights at the north-east and north-west squares and two black knights at the south-east and south-west squares. Exchange the black and white knights in seven legal knight's moves. Note that the center square is never used.	E7 Chifu-Chemulpo
E10 Perplexity Several variations on this design exist. See U.S. Patent 642374 - Shaffer 1900.	E11 Automobile	The Panama puzzle, from 1915. Not in Hordern. Start at the left end of the puzzle - put the three A's in slots 1, 2, and 3, and the other letters in slots 4, 5, and 6. In three moves exactly, moving two at a time that are adjacent and keeping them adjacent, spell PANAMA with no embedded spaces.
Here are more versions of the E10/E11 Perplexity design:
1904 Louisiana Purchase Expo	Shackman Famous Number Puzzle	1915 Panama Canal Expo
	THINK OF JONAH
E15 through E18 clearly presage what has become one of the best-selling puzzles of modern times; Binary Arts' Rush Hour. Move a specific vehicle out the lone exit in the border, first figuring out a way to clear the path of obstructing vehicles. A deck of cards gives progressively harder problems to set up and try. There are several expansion packs with new cards and a vehicle.	E19 Pink and Blue by Nob Yoshigahara 1982 I don't have it or a photo. Play online at Nick Baxter's site. Play other Nob puzzles at Nick Baxter's site.	@                 E24 Mystic Richard Appel Inc. USA 1943 (I don't have this.) Move the purple piece at the top left corner to the bottom right corner - but pieces of the same color may not ever touch sides. Hordern says this can be done in 22 moves.
E29 Fox and Geese I don't have it or a photo. Start with three white pieces (geese) on 1,2,3 and three black pieces (foxes) on 10,11,12. Exchange the black and white pieces moving only along lines and stopping only on circles. At no time except in passing can a fox and goose be at opposite ends of any line.	E30 A New Counter Puzzle From Amusements in Mathematics H. Dudeney 1917 I don't have it or a photo. Start with white pieces on 1 and 2 and black pieces on 9 and 10. Exchange them moving only along lines and stopping on numbered spots. At no time except in passing can a black and white be on the same straight line.	E35 Panex Discussed by Manasse, Sleator, Wei, Baxter in Tribute to a Mathemagician 2005 - see Baxter's page devoted to Panex. Key distinction from Towers of Hanoi: pieces will not descend below their appointed height in stack - 10-high stacks require between 27,564 to 31,537 moves! Play Panex online here, or a simplified version at Cheesygames.
Palette 7 - Doug Engel	Kinokonoyama The pieces interfere with some of their neighbors, preventing some movements.	Takenokonosato The pieces interfere with some of their neighbors, preventing some movements.

A while back there was a computer game called "The Seventh Guest" and a sequel called "The Eleventh Hour." Both were puzzle-based "adventure" games with a horror/suspense flavor. The Eleventh Hour contained a version of a classic puzzle challenge known by various names including the "Crazy Knights" and "Knights Exchange." Adventure games have contained many logic puzzles that yield to mathematical analysis.

Arabesk offers this version of Crazy Knights. (I don't have it.) The Knights Exchange is played on the irregular fragment of a chessboard shown below. For discussion, I have numbered the squares. The initial condition of the puzzle has white knights on squares 6 and 10, and black knights on 1 and 3, and your task is to interchange their positions using only legal knight's moves. This can be done in 40 moves.

+----+
|  1 |
+----+----+----+----+
|  2 |  5 |  8 | 10 |
+----+----+----+----+
|  3 |  6 |  9 |
+----+----+----+
|  4 |  7 |
+----+----+

To solve this puzzle, consider that it might be easier to analyze if you were able to look at it in a different (although isomorphic) way. Starting with the square designated 1, construct a graph where each node represents a square, and each edge between nodes represents a (reversible) knight's move between the corresponding squares. Arrange the graph as a simple unbalanced binary tree with 1 as the root:

         (1)
        /   \
     (6)    (8)
     /     /   \
  (10)   (3)   (7)
                /
              (2)
              /
            (9)
            /
          (4)
          /
        (5)

We've "reduced" the problem to a Perplexity-type puzzle - you can think of the nodes 10 through 5 as a straight track, having a single side branch or "parking space" at 3. You've got 2 white pieces and two black pieces and you've got to shuffle them past each other exploiting the single parking space at 3.

The following is a sequence of moves which accomplish the task. 'B' represents a black knight; 'W' a white knight. B@n means a black knight at square number 'n'. Two numbers separated by commas mean move whatever is on the square designated by the left hand number to the square designated by the right hand number.

You may wish to attempt to deduce a winning sequence yourself now that you have a better representation of the puzzle with which to work (read on at the risk of spoiling whatever remains of the puzzle).

B@1,8,7,2,9
W@6,1,8,7,2
W@10,6,1,8,7
B@3,8,1,6,10
W@7,8,1,6
W@2,7,8,1
B@9,2,7,8,3
W@1,8,7,2
W@6,1,8,7
B@3,8,1,6
W@7,8,3
W@2,7,8,1

If you count the commas (which are moves) you'll see there are 40. Also, note that we didn't need squares 4 and 5 at all.

To solve this puzzle, I've employed a strategy common in mathematics and operations research - when faced with a problem, try to find an isomorphism with another type of problem for which a solution can be more easily found. I'll readily admit that this strategy cannot be used on every puzzle, but I thought this was a great example.

F13 The Combination Lock Mfd. by the Combination Novelty Co. See U.S. Patent 560197 - Dow 1896.	Rectangular Jam, Triangle Jam, and Rightangle Jam designed by Hirokazu Iwasawa Get the highlighted block out through a slot in the south wall. Unusual because you may rotate the pieces flat in the tray.	Da Vinci's Mona Lisa Codebreaker Twisted Mind - another version, using numbers, and with a transparent case.
Heartache - Kohner	Drop Out	Double Sliding - Dario Uri
The Flying Block Puzzle Designed by Dries de Clercq, a gift from Dirk Weber at Ipp28 in Prague. Thanks again, Dirk! Here, sliding, jumping, and rotation are all allowed, but only one piece at a time.	Twist-'N'-Slide Truck

George Newnes was a British publisher and politician who lived from 1851 to 1910. Newnes' interest in entertaining snippets of information was his inspiration for the weekly 16-page penny paper Tit-Bits, which he launched in Manchester England in 1881. Newnes publicized Tit-Bits with a series of contests and promotions - for instance, an insurance scheme where the survivors of any reader killed in a railway accident and found with a copy of Tit-Bits on the body would receive 100 pounds! By 1891 there had been 36 cases. Newnes went on to found the Strand, published from 1891 until 1950. For twenty years, Henry Ernest Dudeney, England's foremost creator of puzzles, had a column "Perplexities" in the Strand. The Strand also first published the Sherlock Holmes mystery series by Sir Arthur Conan Doyle.

Among the promotions associated with Tit-Bits magazine were a series of puzzles called "Tit-Bits Teasers."

Tit-Bits Teaser No. 1 (1927) C19 This is equivalent to the Pennant Puzzle, or Dad's Puzzle.	Tit-Bits Teaser No. 2 (1928) C56,57 This is equivalent to Ching Foo and the Flying Puzzle.	??? Tit-Bits Teaser No. 3 (1929?) (I don't have this.)
Tit-Bits Teaser No. 4 (1930) D22 (I don't have this.) This is equivalent to the Traffic Jam Puzzle.	Tit-Bits Teaser No. 5 (1931) C58 aka The Train Puzzle	16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Tit-Bits Teaser No. 6 (1932) B13 (I don't have this.) A variant of the 15 Puzzle. Start with the first arrangement, remove the 16, and slide the blocks to get to the second arrangement.

Thinkfun has issued a soko-type puzzle called Treasure Quest: 

Railroad Shunting Puzzles (or switching puzzles) have been around since the late 1800s - according to Slocum and Botermans on page 106 of their "New Book of Puzzles," the first U.S. patent was issued to Pryse Protheroe in 1885. I did some sleuthing and the results are summarised in the table below.

You, too, can search the U.S. Patent database. The CCL for "shifting movement" puzzles of this type is 273/153s. Last time I checked, there were 533 hits spanning many different kinds of puzzles. NOTE: to view the patents, you'll need a TIFF plug-in for your browser.

Pryse Protheroe 1885 332211 Employs a turntable.	Arthur G. Farwell 30 Sep. 1890 437186 W.W. Rouse Ball in "Mathematical Recreations and Essays" p.114 (11th Ed. 6th printing 1973, orig. pub. 1892), says he bought a shunting puzzle "some years ago" called the Great Northern Puzzle. The configuration illustrated in the book resembles Farwell's. A similar configuration is shown in the Wagon Works puzzle described on "The Ultimate Puzzle Site: Logical Puzzles." (Warning: Pop-Ups on the main page.)	Charles W. Lurtey 9 Dec. 1890 442445 - this looks like the "Engineer's and Switchman's Puzzle" shown below. See also Burger 1933 below.
James E. Jackson 1891 449881 - 3 cars in the triangle, loco to the right	John Alfred Allen 1892 482957	John M. Rodgers 1901 688339
Frank Lisle Napier 1902 703076 - this is almost certainly the Railroad Pass shown below, by the Napier Mfg. Co.	Martin H. Anderson 1903 Street Car Puzzle 729522	Edward S. Mowry 1903 743015 - W.W. Rouse Ball on p.115 calls this the Chifu-Chemulpo Puzzle, on sale in the streets in 1905. The main line can hold only 8 cars and the spur only 4. To start, 8 numbered cars reside on the main line in order and the engine on the spur. The object is to reverse the order of the cars. See the similar "Good Luck" horseshoe-shaped puzzle shown below.
Henry Keeler Feb. 1904 750862	Orril L. Hubbard Mar. 1904 753266 - using turntable	Livingston B. Pennell Feb 1905 783589
Charles E. Harris Nov 1905 804314	W.E. McGraw & A.M Goodale 1906 822862 - 4 cars in triangle	Harry G. Webster 1907 856749 - switch positions on S-shaped track
John J. Barnes Dec. 1907 874726 - several puzzles using a comprehensive track layout	Solon S. Cahill 1908 878187 - also shown here: Grantham vs. Boston - a simple passing problem with one short siding (aka "blind spur")	John W. Clark 1908 898321
Charles M. Conley 1912 1018879	Thomas F. Young 1916 1174219	John W. Braunschweiler 1918 1275210
John Vandever Wells 1921 1377039 - 2 puzzles, unique switches	Bruno von Bueltzingsloewen 1925 1560921	Maximilian E. Pesnel 1928 1673705
Clarence W. Burger 1933 1920291 - This looks like the Engineer's and Switchman's Puzzle shown below, but shows eight pieces while the actual puzzle has an engine and five numbered cars.	Leo J. White 1964 3127175	William A. Sternad 1973 3767202

Here are some examples of railroad shunting puzzles which have been sold as mechanical puzzles.

Engineer's and Switchman's Puzzle see Slocum and Botermans' "Puzzles Old & New" p.10	Good Luck - Saleable Products (Hordern J7)	A wooden repro of a Protheroe-type turntable	Metro by Binary Arts
Napier - Railroad Pass (I don't have this.)
Chifu-Chemulpo (Hordern E7)
Here is a copy of the Great Northern Puzzle. (I don't have it.)

Shunting puzzles can be built in model railroad layouts, but they are usually considerably more complex than the mechanical puzzles described here. Model railroaders try to create more realistic scenarios using several long sidings, runarounds, and trailing and facing switches. The operations at various industrial locations that require lots of shifting of cars and loads, such as mines, paper mills, breweries, or cement plants, can serve as the objective. Real railroads (known as prototypes) strive to avoid the switchback maneuver common to these puzzles, and operators prefer to do a "grand pull."

Adrian Wymann has a nice site on railroad shunting puzzles. Carl Arendt's site shows many layouts including puzzles.

Here are some model railroad puzzle layouts:

• Operate Riverside Yard (Javascript)
• John Allen's Timesaver
• Inglenook Sidings
• Linn H. Westcott's Switchman's Nightmare; (See also Arendt's site - scroll down and find it in the list.)
• Scot Osterweil's Highland Terminal
• George's Bayside (Scroll down to #251.)