Bachmann has come up with an excellent model of the largest class of steam locomotives on the Chesapeake & Ohio. While a few detail compromises have been made in producing this model, the overall result is a very effective representation and smooth operating model of an important C&O locomotive.
Review: Bachmann Spectrum C&O H-4 class 2-6-6-2 Mallet Articulated Steam Locomotive in HO scale
by Gary Quale/photos by George Riley
Bachmann has recently released a model of the numerous Chesapeake & Ohio class H-4 2-6-6-2 locomotives that served from their introduction as mainline drag power in the early 19-teens through the end of steam on the C&O in the 1950's. In the latter years they could be found hauling empties in and loaded hoppers out of the winding mine branches in West Virginia, switching in the yards where the main line coal drags were assembled, on merchandise trains on the hill and dale lines of central Virginia, and even pulling varnish to the Homestead resort on the Hot Springs branch.
This model is based on the model of the USRA 2-6-6-2 Bachmann offered a few years ago in their Spectrum line. This model history requires a review of the genealogy of the prototype. In seeking a more powerful locomotive to move coal out of West Virginia, the C&O worked with Alco in 1910 to build a single class H-1 2-6-6-2 prototype. While the H-1 was similar to other mallets of the age, it employed some significant new features, including superheated steam, a very large combustion chamber ahead of the firebox, and a firebox completely supported by the trailing truck. The loco exceeded expectations, easily replacing double headed 2-8-0's, so the C&O ordered 24 more class H-2's with minor improvements in 1911.
In the meantime, rival Norfolk & Western was experimenting with 5 class X-1 0-8-8-0's and 5 class Y-1 2-8-8-2's. The 0-8-8-0's were intended as helpers on the N&W's long grades, but were soon relegated to yard duties and were gone by 1934. The N&W borrowed a C&O H-2, and according to N&W's own engineers, it ran circles around their Y-1 in tests. The N&W ordered 15 class Z-1's that were almost identical to the C&O H-2 from Alco Richmond in 1912. These were an immediate success with a tonnage rating on the Elkhorn grade almost twice that of the big class M 4-8-0's they replaced. The N&W followed with more orders in the following years, now classed Z-1a with Baker valve gear, for a final total of 190 2-6-6-2 locomotives in 1918 when the USRA took over the nation's railroads. During this same period, the C&O ordered 150 more 2-6-6-2's in class H-4, near duplicates of the H-2's but with slight changes in the number of boiler tubes. It also obtained 25 near duplicates of the H-4's with the acquisition of the Hocking Valley, which were assigned to class H-3.
The USRA engineering committee decided to base the USRA smaller articulated on the N&W Z-1. Perhaps this was due to the presence of two N&W engineers on the USRA Railroad Committee and none from the C&O, and perhaps it was due to the assignment of an N&W executive to direct the Pocahontas region of the USRA that operated the N&W, C&O, and Virginian Railway. The N&W design was slightly modified to comply with USRA parts standardization policies. Other changes included replacing the slide valves on the low-pressure cylinders with piston valves, increasing the high-pressure cylinder diameter from 22" to 23", and increasing the driver diameter from 56" to 57". While maximum boiler diameter remained at 96", the USRA firebox size and grate area were increased to 115" x 97" and 76.3 sq ft, respectively, from the H-4 and Z-1 dimensions of 108" x 96" and 72 sq ft (72.2 on the Z-1).
Bachmann has moved back down this family tree by backdating their USRA 2-6-6-2 to make it into a C&O H-4. The H-4 model appears to use the same mechanism as the USRA. The H-4 has a new low-pressure cylinder block with the correct square topped valve body, and new C&O style crossheads with brackets for lower attachment of the crosshead links. The difference between 57" and 56" drivers is unnoticeable. The valve gear has not been changed, and is still an abbreviated representation of a Baker gear, rather than the correct Walschaerts. This compromise is fairly noticeable since the reverse links on the H-4 were very visible with their mounting on small triangular brackets behind the guide yokes. As with many models, the eccentric cranks are rather vaguely set, with the eccentric rod pin almost over the driver center. This may reduce the drag of the valve gear for smoother running, but it also reduces the interesting "monkey motion." On the H-4, the rear engine eccentric crank should be set behind (with the crank pin at 6:00, the eccentric rod pin should be at 3:00 on the engineer's side) for the inside admission piston valves, while the front engine eccentric crank should be set ahead (crank pin at 6:00 and eccentric rod pin at 9:00 on the engineer's side) for the outside admission slide valves. More subtly, the radius rod and valve rod connections at the top of the combination lever for the front engine should be reversed to provide proper lap and lead for the slide valves.
The Bachmann H-4 uses the same boiler as on their USRA 2-6-6-2, but has changed details as appropriate to the C&O locomotive. Most significant is the substitution of a C&O style cab with a sloped front below the running boards. The cab includes small platforms just below the cab sides to allow access to the running boards for the crew (the absence of this feature was one of the C&O's complaints about their H-5 USRA articulateds). Both of these platforms slope upwards on the sample we reviewed, apparently from interference with the piping ahead of the cab. Other changes include substitution of C&O style running boards and air tanks, air lines and steam pipes under the running boards, substitution of a steam dome with H-4 contours, and addition of a Nathan low water alarm. The bell, whistle, safety valves, turbo generator and power reverse have been repositioned to their proper locations on the H-4. One noticeable feature not changed is the sand domes. The USRA style domes were not changed to the rounder C&O style, and the rear sand dome has not been moved forward to its proper position on the H-4 above the fourth set of drivers.
Completing the Bachmann H-4 is an excellent model of a C&O class 12VC Vanderbilt tender. Bachmann has included the correct trucks for the tender with ‘horns' at the ends of the side frames to support outside hung brake shoes. The H-4's were delivered with 9,000 gallon rectangular tenders but in the 1930's many received larger 12,000 gallon cylindrical tenders that were hand-me-downs from K-2 mikados and H-7 Cheaspeakes. Other features that date the Bachmann model are the modified cab with partially sloped front and flying air pumps on the smokebox front from the mid-1930's, and the number boards ahead of the stack from the mid-1940's.
The mechanism in the H-4 consists of a skew-wound can motor with two flywheels centered in the boiler, which drives both engines through universal joints and gear towers, much like a typical model diesel drive. Both engines can pivot under boiler, allowing the locomotive to operate down to 15" radius curves, but on these tight turns the overhang is significant with inside back corner of the cab are over the center of the ties. The RP25 wheel sets conformed to the NMRA standards gauge. E-Z Mate Mark II couplers are factory installed front and rear. Directional constant intensity golden yellow LEDs light the headlight and tender back-up light. The number boards on the smokebox are not illuminated. The locomotive comes with a factory-installed Bachmann E-Z Command dual-mode DCC decoder connected by a standard 8-pin plug. In the DCC mode F10 turns the headlight on and off, and function F1 dims the headlight. The bottom of the tender has several small holes to facilitate installation of a speaker for those that want to add sound to their model.
The locomotive weighs 17.1 oz., the tender 3.7 oz., and it produced a drawbar pull 1.8 oz. without slipping. Out of the box, our sample began to crawl at a fairly smooth 0.1 smph at 5.0 V and 0.05 A in the DC mode. Full speed running light was a prototypical 38 smph at 12 V and 0.1 A. Current draw at 12 V with the locomotive stalled and wheels slipping was 0.2 A. In the DCC mode with a Digitrax control system, speed step 1 yielded 0.09 smph and speed step 99 produced 61 smph with the factory settings. Bachmann has come up with an excellent model of the largest class of steam locomotives on the C&O. While a few detail compromises have been made in producing this model, the overall result is a very effective representation and smooth operating model of an important C&O locomotive.