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The Union Pacific 4015 Big Boy 4-8-8-4
circa 1960

Trix model 22599

Review by Neil Wood

Train Cloud Sky Vehicle Plant

10 minute stop to cool the train's wheels
after the long braking descent

from the top of the Wasatch grade. William *****, 1942.

Central to Union Pacific’s network is
the steep line between Cheyenne and Laramie which traverses the Wasatch
Rocky Mountains. At the end of the 1930s freight trains on this route became
longer, faster and required time-consuming, costly double heading with
several locomotives. Union Pacific required a single locomotive
capable of pulling 3,600 tons of train unassisted over the 1.14% grade of
the Wasatch route.

A tractive effort of 135,000 lbs would be
needed to pull 3,600 tons. With an axle loading of 67,500lbs each,
this required 8 drivers or a 4-8-8-4 wheel arrangement. The result was
considered by many to be the most successful articulated steam locomotive
ever built. The first in the series of 25 was delivered to Omaha on
5/9/41. Built in two batches by Alco Locomotive works, the first batch
4000- 4019 was built in 1941 and the second 4020-4024 delivered in 1944.

The last revenue freight pulled by a Big
Boy was in July of 1959. Most were retired in 1961, although the last was
retired in 1962. The average mileage was around 1,000,000 miles.
While there are other locomotives which have exceeded the Big Boy in terms
of weight, length, horsepower, and tractive effort it is generally agreed
that this is the largest steam locomotive to run in regular service.

As this was the largest steam locomotive
in history it created the opportunity to make a superlative model.
This is an expensive model and stands at the top of the Trix HO price range.
This for Trix is no mean feat as their models are generally regarded as
expensive. Billed as the largest H0 steam locomotive ever built by
Trix this was one model I was waiting for with baited breath.

Wheel Train Vehicle Sky Track

4015 under the coaling tower
Denver , 1954. Photo R. Kindig.

Specifications of the 4-8-8-4 Big Boy

Length of the locomotive:


Length (tender):



117' 7"

Total Length Over Couplers:


Top of rail to smokestack:


Driving wheel diameter:



23.75" diameter
with 32" stroke

Timken roller bearing axles

Articulated-type side rods

Walscherts valve gear

Max speed:


Tractive effort:

135,000 lbs. max

Max curvature:

20 deg.

Weight (locomotive):

762,000 lbs.

Weight (tender unloaded):


Tender water capacity:


Tender fuel capacity:

28 tons

Sky Cloud Pollution Smoke Gas

4004 sm okes up
the sky Photo Stan Kistler, 1958.

Trix model number 22599
Released; 2003 Price; US$798 (₤440)

Model specification :
Length 465mm(18-5/16"); Weight
1.2kg (2 lb 10 oz); Running No: 4015; Livery:
Union Pacific; Period: 1960; Features:
Die cast metal locomotive frame, body, tender frame, tender body,
High-efficiency can motor with bell-shaped armature and flywheel in the
boiler, 8 axles powered, centre driving axles spring mounted, RP 25 wheels,
Kadee® compatible couplers, built-in DCC decoder with the following
effects, Acceleration and braking delay, Headlights,
number board lights, backup light on the tender, Light
in engineer's cab, Steam sound effects, Steam injector, Whistle, Bell; Smoke
generator ready, Engineer and fireman figures are included, Close coupling
between the locomotive and tender,

The first impression given is the size of
the box. It’s big! Inside is another wooden presentation box.
Once opened you get your first sight of the locomotive. It is immense.
The box is foam lined to protect the model. Due to the heavy weight it
is secured onto a wooden display plinth by three screws. There are
optional parts for the front guard, driver and fireman figures, a two year
warranty, an assembly diagram and multi-lingual operating instructions.

Material property Gadget Wood Gas Office equipment

The first thing you want to do is fire
her up and see how she goes, however first you have to remove her from the
display plinth. This isn’t easy as the loco and tender have to be
unscrewed from the plinth. When unscrewed it drops into the foam box
underneath. Due to the weight of this model it can be awkward to get
the loco out of the box while upside down then turn it the right way up and
place it on the track. While the carry box is a good idea for
transporting and presenting the model, it isn’t easy due to the difficulty
in moving and securing the loco and tender.

Train Wheel Land vehicle Vehicle Rolling stock

On the tracks it is an imposing model.
It will be the largest loco on any HO layout. There are seven digital
functions, front and rear lights, Cabin light, minimising starting and
braking delay and four sound effects, basic operating noises, bell, whistle
and injector. I had expected more than four sound effects. The
Marklin Big Boy with the MFX decoder had sixteen digital functions so I felt
slightly short changed.

Train Wheel Vehicle Rolling stock Track

When it moves off it does so slowly with
the inertia expected from a gigantic locomotive. The sound is
coordinated precisely with the motion of the loco. Operating noises
like brakes squealing are triggered by changes in motion. It may be
disappointing to some that the operating noises are not all individually
controllable and are automated. Similarly the whistle length cannot be
controlled. It is preset to a specific length. While this did
not bother me to start with, it does now. The sound is loud. It is the
loudest loco I have heard. The bell is so loud I hardly use it at
home. My wife complains from the other end of the house! The
sound level would be ideal for exhibitions.

There are provisions for two smoke
generators. When combined with the sound the overall effect is very

Train Rolling stock Nature Vehicle Track

With all those wheels you would be
correct to be concerned about derailments. However, as long as
it is not run through points at high speed there are no problems.
Consideration has to be given to the track radius. The manual
recommends 450mm but says it can be run on as little as 360mm. Another
consideration is the large overhang as the loco goes round corners.
Careful thought has to be given to the proximity of buildings to the track.
The tighter the radius the greater clearance required with 34mm being the
maximum required.

Train Rolling stock Vehicle Locomotive Rolling

Train Land vehicle Wheel Motor vehicle Automotive tire

The ride is very smooth with no noise.
With the sound turned off it glides silently around your layout. The
detail is incredible and unlike cheaper models it is securely attached.
It takes a lot more than brushing against a model tree to knock parts off of
this. This is a model that is built to last.

Train Wheel Vehicle Toy Rolling stock

The competition comes from Rivarossi who
make a budget model. It is DCC ready, a plastic body, no lights, sound
or smoke generator provision. It is aimed at a budget market and
not comparable to the Trix item in terms of features, detail and build
quality. At a third of the price it may be better value for those who
do not care for extras. The Athearn Big boy has sound, lights and
smoke generator provision. It costs a third less than the Trix model
but having a plastic body instead of a metal one does not have the
robustness of the Trix model. The sound decoder is no match for the
Loksound one. If you are considering $500 for the Athearn then you
should definitely consider the extra $300 for the Trix. The real
competition will come from the forthcoming release by Precision Craft.
They make a model which is almost identical in specification but is $50
cheaper. It has metal body, Loksound decoder, directional lights
although no provision for a smoke generator. The decoder seems to have
more functions and options for programming. This, however, has not
been released yet.

Train Vehicle Wheel Mode of transport Rolling

Overall this is a fantastic locomotive.
It is beautifully detailed and with sound, steam and lights going is
extremely impressive. The down side is the cost and the sound effects
are mainly automated rather than individually controllable. Being
realistic though how many modellers really know when all the individual
sounds would be appropriate? I admit I wouldn’t. So maybe it
is not such a bad idea that the decoder does. So is this a superlative
locomotive? In many ways yes, if bought, it would certainly be the
centrepiece of many collections, however there is competition on the way.
Marks out of ten? I’d give it nine and a half. It costs a lot
of money but it sure is a lot of locomotive.

Programming Table of the most
important CVs




Factory setting


Locomotive address




Starting voltage




Acceleration time




Braking time




Top speed




Middle speed




Restore basic factory settings




Configuration Register






Noise volume



Neil Wood - May 2006

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