The PushMePullYou G Scale Shunting Puzzle

Logic puzzles intrigue me. Over the years, they have helped while away the hours on many a flight between Australia and the USA. Having devoured the material on the wonderful Wymann web site (http://www.wymann.info/ShuntingPuzzles/index.html), I was keen to create a shunting puzzle both for my own enjoyment and as a fun learning environment for our grandchildren. The result is PushMePullYou.

G Scale trains are robust compared to smaller-scale equipment, a distinct advantage if youngsters will be operating the railroad. However, the size of G Scale locos and rolling stock made the creation of an indoor Inglenook or Timesaver a daunting proposition because the layout had to fit into a 50 sq. ft. (about 4½ sq. m.) area and use carriages 16” to 22” long.

Carl Arendt’s Smallest (interesting) Inglenook? provided the inspiration for PushMePullYou. Arendt’s original idea and track plan can be found at http://www.carendt.us/microplans/pages/a3/index.html; scroll down to find it.

Arendt’s layout fit on an A3 sheet of paper, but we felt it would scale up nicely. The track plan we extrapolated from Arendt’s model appears below.

First concept, based on Arendt's model

A bit of experimentation proved that the amount of space available (PushMePullYou is built on four tables each five feet long and 2½ feet wide) permitted more complexity than the first concept had envisaged. After further prototyping, this is the track plan we settled on:

Final concept, utilising all available space

We had ample track, a mixture of locally-produced Australian flex and Aristo, but no switches. We purchased the six we needed, three each of LGB 12000 (right-hand) and LGB 12100 (left-hand) manual R1 switches. The layout has some tight curves, and some brass filler pieces had to be fabricated to close particularly ugly gaps in the track. The final result fit neatly onto the tables.

PushMePullYou - the start position is off picture, top left

Start position

At the start of a PushMePullYou puzzle, the train passes under the mountain, crossing switch S1, located just inside the tunnel mouth. S1 provides access to the two curves that are at the heart of the puzzle or, alternatively, a way in to sidings C and D. If the latter route is chosen, switch S2 determines which of the two sidings the train uses.

PushMePullYou

S3 controls whether the train uses the inner curve or the outer curve. The inner curve provides the only way to siding E, via switch S4. Sidings A and B can be reached via either curve, with switch S5 determining the curve that gets access and switch S6 arbitrating between A and B.

A synopsis of switch functionality follows:

S1 (under mountain)	access to curves OR access to sidings C and D
S2	siding C OR siding D
S3, S5	inner curve OR outer curve
S4	siding E
S6	siding A OR siding B

PushMePullYou is a mini-world in which our grandchildren can exercise their imaginations. It incorporates a mountain with a tunnel, a Dickie battery-powered crane, a level crossing (LGB 50650) and a scattering of trees made from dowel and clothes line. There’s also a mélange of toy people, vehicles and animals to complement the trains.

As you can tell from the trees, realism isn’t a priority. Tasks such as “Use crane to lift walrus from top of blue car, placing walrus next to man in pink suit on top of mountain” are very much on the agenda!

Motive power for PushMePullYou is a USA 20-ton switcher run by track power provided by a small (22 v, 1 amp) LGB 50084 transformer/controller. Rolling stock is a mixture of USA 40’ and 50’ boxcars and reefers, AML 40’ boxcars and a USA extended vision caboose. Other cars of similar length could be employed. For the moment, we like box-shaped units where each car is a different colour. At this age (five and 3), the youngsters love operating the doors and putting stuff into the cars!

Some of the cars used in PushMePullYou

The capacity of each track section appears below (loco fits with each combination). The capacities are variable, depending on whether or not the operator is willing to block other switches, so they should be used as a guide only. Part of the fun of PushMePullYou is finding new and interesting ways to push and pull both single carriages and carriage sets into the positions, or order, required.

Sidings

A	1 X 40’
B	1 X 40’
C	1 X 50’ OR 2 X 40’ OR one of each
D	1 X 50’ OR 1 X 40’
E	1 X 40’

Other track

Start, up to S1	1 X 50’ OR 2 X 40’
Start, up to S3	4 X 40’ OR 3 X 40’ + 1 X 50’ OR 3 50’ OR two of each
Inner curve	1 X 50’ OR 2 X 40’ OR 2 X 50’
Outer curve	4 X 40’ OR 3 X 40’ + 1 X 50’ OR 3 50’ + 1 X 40’ OR two of each

All couplers are H&L. In the future, we may look at automating coupling and switching, but for the moment everything is manual. We use a long, thin flat-blade screwdriver to facilitate uncoupling.

PushMePullYou puzzles are not intended to be speed sensitive. We want to encourage our grandchildren to reflect and plan, and to understand that real trains are very large, hard to stop and potentially lethal to anything unfortunate enough to be in their way.

There’s no scoring system for PushMePullYou. If we ever devise one, it will be safety-oriented. We might start users with 100 points, then deduct points for derailments, avoidable contact (some of the clearances are very tight) and mistakes in coupling and switching (get it right the first time). A vehicle could be placed athwart PushMePullYou’s level crossing after the train moves out, with the stipulation that it can’t be moved for five minutes. If the user forgets to shift the vehicle and it gets hit by a train, the user goes directly to jail - do not pass GO, do not collect $200!

Two examples of PushMePullYou puzzles follow. I find it relaxing to dream these up, then find a way to solve them. If you can see a more efficient solution, fire away! I lay no claim to having devised the most elegant solution to either of the two sample puzzles.

David Healy.