Precision Craft Models
4-8-8-4 Union Pacific Big Boy Locomotive with DCC and Sound

Precision Craft Models, Inc.
4 Signal Avenue, Ste. A
Ormond Beach, FL 32174

HO Scale
4-8-8-4 Union Pacific Big Boy #4024 Locomotive with DCC and Sound
MSRP $749.99

The Precision Craft Union Pacific is a beautiful model of a popular prototype. The model reviewed was a stock number 576 model of UP No. 4024 circa 1944 with a 26-C-400 tender and equipped with DCC and sound.

Construction:

The locomotive and tender are clean and well-detailed metal die-castings.

Both engines are powered and both pivot near their midpoints to allow operation down to 18” radius. On each engine, the first and third drivers are fixed and the second and fourth are sprung. All drivers are flanged. The second and third drivers on each engine have slightly more lateral play than the first and fourth to help negotiate tight curves. Similarly, the second, third and fourth axles on the tender pedestal truck have additional lateral play. All wheel sets conform to the NMRA Mark II (RP-25) standards gauge.

On a test layout, the locomotive operated smoothly on 22” and 18” radius curves as advertised. The rear engine seemed to be particularly sensitive to having good track work on these sharp curves, and did initially derailed on a hitherto undetected kink in the 18” radius loop. Eliminated this slight kink did yield smooth, trouble free operation. The locomotive operated smoothly through #6 turnouts at all speeds, and #4 turnouts at switching speeds.

The model is more at home on 24” and greater radii curves. On 18” curves, the overhang is significant - the back of the cab roof is about 3/8” outside the NMRA clearance gauge, and a little more than 1” outside the outside rail.

Overall construction rating - 4.8

Detail:

The reviewer feels that a neatly applied Bob Darwin / CalScale X-2008 150 piece superdetail kit with all associated piping represents the standard for detailing UP Challengers and Big Boys. The Precision Craft Big Boy betters this standard. The die-castings are all crisp and free of any flash or visible mold parting lines. Small piping and handrails are separately applied blackened wire. Larger piping, and the larger appurtenances including the right side injector, turbo generator, exhaust steam injector and turbo pump, and power reverse are apparently brass castings that include all the associate piping as subassemblies. All this larger diameter piping casting are flash free and appear to have round cross-sections on close inspection.

One detail nit is on the tender where the cables to the electric markers are cast into the back of the tender as raised semi-circular loops. This does not seem to be in keeping with the quality of the other applied detail, and is especially problematic for modelers who want to remove the electric markers (see comments below).

Overall detail rating - 4.8

Conformity:

The locomotive reviewed is a model of Union Pacific number 4024, the last of the 25 Big Boys. It represents one of the second group, 4020 through 4024 delivered in 1944. This group had a few changes from the initial 20 locomotives, including use of Type A instead of Type E superheater and use of heavier low-alloy steels due to war-time restrictions (neither externally visible), and moving the air compressor after-coolers from the top of the pilot deck to down behind the air compressor shield just above the pilot beam (an upgrade later retrofitted to the earlier group of Big Boys).

The model compares favorably with scale drawings of the Big Boy by E. W. Bearman. A few compromises have been made to allow operation on sharp curves. The front engine has been moved forward about 12 scale inches to provide more clearance between the engines. The pilot truck has been moved forward about 3 scale inches and the pilot about 6. The locomotive to tender spacing is realistic appearing, but is in fact about 12 scale inches more than the prototype. (Note that the snap-together drawbar does not provide alternative spacing.) Thus the overall length of the model from tip of pilot to back of the tender is 18 3/8” or 133’ 4 1/2”, as compared to the prototype’s 130’ 9 1/2”. The overall wheelbase of the model is 16 1/2” or 119’ 9” compared to the prototype 117’ 6 5/8”.

As delivered, these locomotives:
* Had the turbo-generator mounted on a platform suspended down behind the right rear drivers and ahead of the trailing truck. The generator was later moved to the top left of the boiler just ahead of the cab turret casing.
* The pilot couplers could be rotated out of sight behind a panel complementing the rest of the Commonwealth cast pilot. Later the couplers were semi-permanently mounted in the deployed position.
* The mechanical lubricators were actuated by small connecting rods attached to the Walschaerts valve gear reverse links. The rods were later replaced by “bicycle” chains protected by sheet metal shrouds.
* The clam-shell smoke hood which deflected the blast from the stacks to the rear when the Big Boys operated in tunnels was actuated by a small air line running directly forward from under the boiler jacket and along the smokebox. This did not supply sufficient air pressure to always fully deploy the smoke hood, and was replaced by a larger air line running directly from the right main air reservoir up at an angle along the smoke box.
* Did not have coal-boards on the tender. Photos show that they were added as locomotives were shopped in the mid to late 1940’s.
* Were part of a paint test, and had the paint type stenciled on the back of the tender just above the coupler. This lettering was not duplicated in subsequent repaintings.
* After shopping, pressure test data was stenciled on the sides of the main air reservoirs. This data does not appear in builder’s photos or photos of the Big Boys when new.

The Precision Craft Big Boy reviewed correctly models all of the foregoing 1944 vintage details.

Some tender details are not appropriate for a second series Big Boy in 1944:
* The model has electric markers on the rear of the tender. These were an as-delivered feature of the first 20 Big Boys, but were often removed and misplaced and so were not repeated on the 5 war-babies. Late in the lives of these locomotives when they were in helper service, they did carry markers, but these were oil-type.
* In the mid-1950’s the UP added a water spray nozzle just above the red taillight. The Big Boys were prone to discharge hot cinders that could start brush fires. A line was added to take water from the left injector’s discharge, run through the tender water space to cool the water, and spray back on the roadbed. The 1944 era model incorrectly includes this nozzle.

The Precision Craft model comes with a bag of extra parts that include a Kadee-compatible coupler and coupler pocket for mounting on the pilot (the pilot coupler door will not close with this coupler installed), and a snap-on raised smoke hood. The reviewer was not able to locate any photos of a Big Boy with this hood fully raised. Apparently author Kratville had the same problem, and includes only a pencil drawing in his book “Big Boy”. Precision Craft may have used this drawing as the guide for making the snap-on hood, which like the drawing has only two instead of the correct three sections on each side, and which don’t curve down to the pivot points at the front of the shroud around the stacks.

Overall conformance rating - 4.9

Finish and Lettering:

The model is nicely and evenly painted in a slightly satin flat black with dull silver smokebox and firebox sides. The dull silver color is about mid-way between typical model “old silver” and “graphite” paint colors, and seems to be less bright than the shade evident in photos of second series Big Boys from 1945-46.

The locomotive has the correct five safety valves on the boiler, one open type and four muffled type. Three of the muffled valves are supplied in a bright brass finish, while the other two are dull black. All five valves should have the same unpainted, almost-black, dirty-bronze finish. The bright brass whistle should also be this darker color.

The side rods and valve gear have a pleasing gunmetal finish. The coal pile on the tender is an unpainted plastic snap-out insert, so that the “black diamonds” have a more glossy finish and glint realistically.

The lettering is neatly done in white and appears to be correct for 1944. The lettering includes the loco numbers on the headlight wings. The model has separately applied builders and equipment trust plates (all the text on the trust plate is legible with a good magnifying glass!) on both sides of the smokebox plus a third plate on the right side. The UP shield with the correct loco number graces the pilot.

The model includes lighted headlight, backup light and number boards. These all use LEDs that seem a little too yellow to the reviewer. The backup light comes on and the headlight dims when the locomotive is in reverse.

Overall finish and lettering rating - 4.7

Performance:

The Precision Craft Big Boy ran very well out-of-the-box in both the analog and digital modes. Using a Digitrax system, the locomotive took 45 seconds to smoothly move 12 actual inches on a level test track in pre-set speed step 1, which equates to a scale speed of 1.3 MPH.

Weighing in at a massive 2 pounds 11 ounces sans tender the Big Boy exerted a drawbar pull of 5.8 oz. without driver slipping. This equates to at least 75 free-rolling freight cars on straight and level track.

Sound:

The stack sound is not as full as could be desired, but one must recognize speaker size limitations on deep bass tones, even with the dual speakers provided. The sound unit has a feature that simulates the two engines shifting in and out of synchronization with each other. The effect is good at lower speeds, but runs full cycle (in sync - out of sync - in sync again) in about six feet of travel on the layout. This is good for a stationary visitor observing the locomotive passing through a scene, but becomes tiresome for an engineer following the loco on a walk-around layout. Of a half dozen old recordings of Big Boys in service, only one starting sequence comes close to as much change in sync as on the model. It should be noted that the drive system keeps the drivers on the two engines in the same relationship. On the reviewed model, the lead engine was about 60 degrees ahead of the rear engine, which would be close to maximum out-of-sync stack noise.

A disadvantage is that the in and out of sync feature continues as loco speed increases. This seems to prevent the stack sound from transitioning into the continuous roar that characterized Big Boys at speed. Instead, the stack sound seems to peak out at about 35 MPH in very rapid “putt-putt-putt...” short bursts of white noise-like sound. Turning down the sound volume from the factory-supplied maximum setting helps to improve this.

The whistle sound is very good. Again, in an ideal world, the whistle should be a little more barrel-chested (i.e. deeper and fuller), but given speaker limitations the whistle is very respectable. The whistle sound ends in a “whistle artist” embellishment extra short toot. By starting the subsequent blasts quickly enough, one can avoid the after tone on all but the last long blast in the grade crossing signal (—.-) for a very nice effect.

At first hearing, the bell sound seemed to be too rapid and almost like a crossing gate bell. Checking prototype photos showed that the Big Boy air ringers were the internal clapper type rather than the external piston type that rotates the whole bell, so the more rapid Diesel-like repetition rate is appropriate.

Overall sound rating - 4.5

Other Comments:

As received, there was only one minor defect with the Precision Craft model. The model includes brake beam and pull rod assemblies which snap onto the bottom of the engine frames between the brake hangers. The rear brake beam on the front engine was loose and bent from the pressure of the foam packing. The plastic was pliable so that it was a simple matter to snap the brake beam back into position.

The reviewer was very impressed with the overall appearance, accuracy, and operation of this fine model. The Precision Craft Big boy is highly recommended to both UP modelers and to others who want a model of one of the largest steam locomotives ever built to dwarf the rest of their rosters.

Reviewed by  Gary Quale