Earlier in the thread was a discussion of the British Rail (BR) class 22 (diesel-hydraulic, DH) and class 21 (diesel-electric, DE) locomotives, which were intended to be counterparts for transmission comparison purposes. Although some of the differences between the two were probably inevitable, another factor may have been that the 22 design was likely substantially completed before the 21 was conceived. The builder, NBL, had been lobbying BR to buy some diesel hydraulic locomotives quite early on, and the orders for what became the 41 and 22 classes were apparently placed before the Pilot Plan, covering prototype diesel-electrics, was developed. As mentioned, the 21 was ordered because BR thought it should have a direct comparison between DH and DE types. The intermediate power range into which these locomotives fell was BR’s “sandbox” in the Pilot Plan. The other “experimental” types, neither of which was likely to result in production orders, were the class 23 (EE “baby” Deltic”), because BR thought that it should at least try the Deltic powerplant, although at the time it had no intention of using it more widely, and the class 28 (Metropolitan Vickers Crossley Co-Bo), because it thought that it should include a medium-speed two-stroke engine in the mix.
Anyway, that the 21 and 22 were not designed in parallel would have meant that the 22 was designed without any consideration of a DE counterpart. In turn the opportunity for maximum commonality was probably foreclosed. One reason for the use of Commonwealth bogies on the 21, rather than something similar to those on the 22, may have been that NBL was already overtaxed, so that the easy pathway was to use a third-party design.
Aside from the BR case, SNCB, Belgium undertook a direct DE vs DH comparison in the early 1960s, when it started its acquisition of medium-powered line-service locomotives. It did not seem to be all that serious about it though. Although one DH model was ordered at about the same time as its DE counterpart, the other was somewhat delayed. And bulk ordering of the two DE designs started before any serious comparative studies could have been completed. Possibly there was a faction within SNCB who thought that DH line service locomotives should be given a try, perhaps influenced by their apparent success in Germany, and in particular, the maturation of the DB concept with the advent of the V160 class in 1960, much simpler and more economical than the complex flagship V200.
In the second half of the 1950s, SNCB had built up a fleet of DE locomotives in the 1750 to 1950 hp range, using both Cockerill-Baldwin and licence-built EMD designs. The same two supply options were also invoked for the medium-power DE locomotives, type 210 (later series 60, 61) from Cockerill, and type 212 (later series 62, 63) from Brugeoise et Nivelles (BN), by then the Belgian EMD licensee. The DH counterpart to the 210 was the type 211 (later series 64), but although having the same Cockerill-BLH engine as for the 210, this was to be built by ABR. They were probably designed more-or-less in parallel, and Cockerill probably had some involvement with it, given that it was the engine supplier. The engine was the Cockerill-BLH TH895SA.
This diagram shows the both the original type 210 (production versions were slightly different) and the type 211.
(104.7 KiB) Downloaded 335 times
The Type 212 (later series 62) was the EMD AA12 model, fitted with the 12-567C engine. The AA12 had previously been listed and built by EMD’s German licensee, Henschel, and was more-or-less a twin-cab version of the G12. Licensees had quite a bit of flexibility when it came to body design though, and the Belgian AA12 certainly looked a lot different to those that Henschel built for service in Egypt. The 213 (later series 65, then 75) was a DH version of the 212, and had EMD designation DH12. It was not built until 1965, and as a consequence had the 12-567D1 engine rather than the 12-567C. Whether much consideration had been given to the DH case when the 212 was laid out is unknown, but probably not much, given that it was a variation of a standard design. Thus the 213 could be viewed as a DH adaptation of the 212.
(148.1 KiB) Downloaded 335 times
Just six each of the 211 and 213 were built, whereas the totals for the 210 and 212 ran to over 100.
Both DH types used the Voith L216rs transmission. This had two torque converters and one fluid coupling, the latter used in the highest speed range. That approach seemed to be in vogue at the time, having been used for the DB, Germany V160 prototypes, which had the larger, but otherwise similar L218rs transmission. The fluid coupling third stage was probably more efficient, but that was traded off against reduced power utilization. The idea did not seem to have a lot of merit for line service locomotives. Both SNCB diesel-hydraulics also had two-stage transmission output gearing, again following the V160 lead. This provided faster gearing for passenger service and slower gearing for freight service, changeable only when the locomotive was stationary.
The 212 had the standard EMD eight-notch control system, using the Woodward PG governor. It probably had the standard EMD master controller of the time. The 213 was different though. For DH locomotives whose transmission included a fluid coupling, as in this case, direct control of the fuel rack combined with a min-max governor was preferred over conventional speed control. Here the rack control was obtained using a Westinghouse eight-position electropneumatic device. There was no mention of the Woodward PG governor, so it would seem that EMD had used an alternative min-max unit. In the late 1950s, Westinghouse had developed both three-piston, eight-position and four-piston, 16-position linear electropneumatic operators that could be used for engine fuel and speed control, and hydrodynamic brake control. DB used the four-piston version to provide 15 notch control on its V100 and V160 class locomotives. In the SNCB 213 case, eight notches was a relatively low count for a diesel-hydraulic locomotive of the time, given that experience by then indicated that somewhere in the 14 to 16 range was preferable. Possibly it was done to allow the use of the standard EMD master controller. The 213 appears to have been fitted for MU, but whether or not it was compatible with the 212 is unknown.
The 210 had the ACEC-Westinghouse continuously variable pneumatic throttle control using the Woodward UG8 governor. The master controller looked like the Baldwin CE100 or something very similar. The 211 had a Westinghouse continuously variable pneumatic control system, apparently with a Westinghouse master controller. Presumably the control was of the fuel rack rather than the speed type, but this is unconfirmed.
Thus the SNCB case provides another view of a situation where diesel-electric and diesel-hydraulic locomotives were designed for the same basic job and with significant commonality. If nothing else, it confirms that for single-engine installations, the two cases required significantly different engine placements on the frame.
I am not aware of any other cases where “maximum” similarity/commonality DE and DH locomotives were acquired by a railroad system. Certainly there have been cases where DE and DH locomotives have been designed to a common specification or requirement, but were otherwise very different, as in the British rail class 47 (DE) and 52 (DH) cases.
Cheers,
