Body and Chasis
Originally EE intended to build the locos on the D600 DP3 body and chasis, but the amount of internal equipment and space needed for large radiator banks entailed a longer loco. If built to the Dp3 type the overall weight would approach 127 tonnes, which to some extent defied the point of having a gazelle like high speed, light weight loco.
In practice the 22m long deltic chasis was elongated by 1.4m and stregnthed by both additional tubing and box section, particularily around the drag box and the bogie ride-plates. The weigth in operation could therefore be held at a planned 112 tonnes, although with some extra equipment seen as desirable and the long range fuel tank filled they were almost 118t.
The body appearance was as noted very similar to a DP3 with the roof and side panels looking pretty deltic like. The two noticeable mencahincally relateddeviations from these relatives were the larger top fans and the extension of radiator grills on one panel down below the roof unit. Secondly was the addition to the otherwise clean D600 layout of a traction motor blower/extractor on the 2nd mans side of the cab/nose area. This operated as a blower on lead end and as an extractor on the trailing end. Also a larger side panel air intake and heat exchange unit and as mentioned the indicators panels being central on the front end with a horn grill and cab ventilator neatly designed on the cab roof.
Aesthetically the loco had tumble home sides which saved some more wieght in the desing, the chasis being narrower than a deltic, while allowing good internal room for access and walking throught the compartments. At a distance the loco could easily be mistaken for either the Brush type 4 or it's own cousin the DP3 (class 50). However from the side the window and cab front panel was far more raked and the lines were more streamlined in all 'joins' to the rest of the loco.
As a final aerodynamic touch, incidentally never fitted to the first two delivered, the buffer sourounds were treated in an aero surround pretty like kestrel, but with a rubber collar providing more streamlining behind the 'sawn off' buffer.
Beneath the buffer beams an aerodynamic spoiler and air feeder for the Traction motors was fitted as a prototype to the fourht delivered loco, and this was a feature either fitted or retro fitted to most of the fleet members which maintained their air brake only status. Those ordered with vacuum systems, about half way into the delivery, and those retro fitted had these 'boxes' removed and new items were not desinged until their HGR in the late 70s to 1980.
At one point 2nd men and fitters were really fed up with the system of hauling out a sliding bucket-door to release the air brake hoses and the main drag box, that they often left them open with the appendages dangling over. THis practice was 'mentioned in dispatches' as disciplinary matter if any train arrived in this state, as the pipes and drag bar damaged the 'cosmetic' light steel box in traffic. The original issue employees took with the set up, was that the box filled with grunge, oil and water thus they became hard to open, and once opened could douse the unwary 2nd man in a filty shower just at the start of a 6 hour shift!. Some simple grease-gun ports and holes drilled in the boxes lead to satisfactory operation alhtough the whole assemblies where prone to rusting.
Traction Mechanicals
As noted in part one, the bogies were the self same 'commonwealth' design as the type 3, deltic and three variants of type 4 carried. However they were the most 'modified'. Apart from being 'beefed up' in terms of corner castings, armature connections, axels and bearings, there were small concessions to aerodynamicity made on the run of no.4 to no.10. These were later removed as they attracted grime and dust, which in proxmity to brakes and traction motors was really an unwelcome side-effect.
Despite the bogies themselves being by in large unremarkable, the operation of these was far from that which had come before. Firstly 110mph tests on Deltics, DP2 and Dp3 revealed a worrying 'yaw' effect at high speed ( we can presume given a 10% error in loco speedo that some of these tests made 120mp- the targey max cruising speed of the supers') . WHen the locos met an uneven picec of track bed, a highspeed point or a change in cant to curve they had a tendency to pivot , rise and float on their bogies. Drivers knew that the loco would settle down but given the wrong type of circumstances BRB and EE reckoned this could lead to dammage to the bogies or indeed collision with platform edges or worse still another loco coincidentally 'yawing' in the opposite direction.
One approach in solving this problem came from a development from the other end of the speed range. Dp3s were fitted with a hydro-pneumatic support system for the bogie mount which overcame the tendency of locos to 'sit back' on their trailing bogie under hard acceleration. This was developed further for the supers' in provding at high speed when this effect also is apparent.
the hydropneumatic set up also assisted in dampening longdituindal and lateral rocking effects, but yawing effects were stil of concern. That is to say yawing on a loco the combination of lateral and long' ways movement pivoting in 3 dimensions around the locos high speed centre of gravity, being a little altered from suib 90mph position. To be even more safe in this respect dampening hyraulics were utilised. These controlled the rate and range of body movement relative to bogie and were speed sensative. They also found use at lower speeds however in making the ride over points and over sharp curves and cants more comfortable for the crew and less mechanically 'jarring' for the bogies, bogie mounts and the drag- bar and to some extent facilitated slight improvements in train haulage.
Unlike the later class 50s, in which these sytems were either not fully fitted or under used, the system ont he SDs was in everyday use and well liked by crews- so much so that any unusual movement or the hydraulic fault light on the panel woudl lead to report of this. Good inspection cycles and regular maintainance kept these somethwta complex systems on the go, and later modifications in the 79-80 HGR rendered them a 3500 hour inspection to fall in line with the PUs.
Traction Electro-mechanicals
We are of course talking about the following:
- Main Generator
- Starting system
- Power Relay and Field Diversion Systems
- Demand Control Systems
- Governing Systems
- Traction Motors
- Traction Control
- Monitoring and Display
(And lastly you can include rheostatic braking, although how effective this was is still a matter of debate!)
Main Generator ( and necesistated seperate starting system)
The main generator was a new development to take 1.5-2kw range mechanical oututputs and convert this as efficiently as possible into direct current. The units were smaller than those for the other EE type 4s, being the same legnth as the deltic predecessors but fatter. It was considered the use of the emerging alternators but Brush and GE of the USA had several patents and pending which meant at this point EE persisted with generators.
The new design did not lend itself to being used as a starter motor, which meant the PUs required a solonoidal engage/disengaged starter motor and further to succesful, prompt starting fromt he rather small battery bank available, the engines were initially co-started with compressed air from the locos own air brake reservoir. The latter was subsequently abandoned because the locos actually started undr just the motor only given full batteries-also the air being drawn from a critical supplywas seen as hazardous and it was designed out under the first D,E and F exams and all were finnalyy removed by 1980. In concession to the need for alternative starting, the starter circuti could take a feed from the ETH circuit if attached to a live loco or platfrom/depot connection. This it must be said has often been the saviour of a superdeltic on a far flung diagram with poorly maintained batteries!
Power Regulations and Field Diversion
The Power was managed thorugh the main circuit by load regulation in two ways..that is to say amps and voltage ratio are controlled in relation to engine output, driver demand and traction motor electro-magnetic feedback. Firstly as is standard on all DE locos there is field diversion circuits. These are switchable sub circuits which allow for several different increments of voltage to be supplied across / from the main generator circuit to the traction motors. As TM rpm increases, so the efficiency of delivering power in a certain voltage range deminishes by the effect of EMF and the amps begin to fall off sharply as the peak is suprpassed. Hence the circuit is switched to a new voltage/amps ratio for reaplication of engine power. These field diverts are a some what crude means alone fo delivering power and require that the generator be put out of circuit. This usually requires the PU to completelyt back down, as is notable on the brush type 4 and the EE type 3 and 4s.
Due to the high speed design spec of the type 6 passenger loco brief, the systems chosen were based on 4 main field diverts.
However the latter order of DP2s and their substituted D600s were fitted with a KV10 load regulator system which manages the circuit better within each field divert allowing the PU to work at or within 80% most effecient mechanical rpm/torque. This was also employed in the supers' in a pair of KV12 regulators with the KV11 load balancer actuially controlling hte main circuit and providing 'demand and balance' criteria to the twin KV12s for each of their own generator circuits.
Engine RPM Control in Respect of Power Demand
In effect this allows the turbo charged deltic engines to work between a minimum 60% and 80% of their rpm range upon demand from the handle, greatly increasing reliability by avoiding excessive thermal cycling. There are though desptie the clever KV systmes, usually two notable field diverts as heard by engine note backing down to near idle. Also the thermostatic shut down which often occurs when the loco has worked under high ampage for prolonged periods i.e lower speed, stop-starting and hill climbing.
A balancing act....
The engines back down when a full swithc to the next higher voltage circuit at it's minimum amps is stipulated by the 'software' (originally all valve and heavy transistor sold state stuff) inside the Kvs. The Kv12 detects the acceleration, the fall in amps, the TM temperatures and the main circuit condition in light of driver demand handle position and then determines if the engine mechancially should be slightly backed off or if they should be shut to notch zero. It then instructs the KV12s to control their engine rpm and circuit according to the lowest amps now required and then switchedss the main circuit over to the new field divert, then modulating the new voltage/amp start thereafter balancing in the two circuits with feedbakc to each KV12 to prevent large misblanace or overload.
Complex Weak Field, Haulage and Traction Motor Temperature Management
In effect when there are 'hot' or rapidly heating TMs the KV12 always chooses to back engine power down and allow for extended cooling for five or ten seconds before then allowing a lower amp/ higher voltage environment to be applied and even this more cautiously, in terms of demand for rpm.
Conversely when the driver has selected the 'start-on-gradient' or 'heavy load' buttons the KV12 will allow for maximum amps to be laid down relative to speed at each field divert and will switch out of divert one either very early or very late depending on acceleration, thus controlling a shut to near idle state at "diversion".
Drivers and enthusasits a like notcie very much when a locomotive is in 'heavy load' and 'gradient' control if there is a lot of stop and starting or 'slacks' for yellow signals. Usually this resulted in maximum engine rpm in both divert one and two, followed by sluggsih progress in 3. This is in part due to thermostatic detection of warming TMs but was also seen as weakness in 'software' execution and overcome in the last full class HGr of 79-1980.
To stand further apart from Deltics, the supers have one major difference in normal operation. The design brief was to haul slightly heavier trains on steeper gradients with more stops and hence better acceleration than deltics, which had been trialled on the route (and continued on the Edinburgh adn Aberdeen to SW services through to Plymouth at the same time and for years after SDs worked the WCML, all be this with a timetable slower in pickups and with fewer planned stops.) The draw back of the deltic on the route was that they engage only one 1650hp engine and this at lower tractive effort than the comparable type 3 due to the higher voltage cirvuits. The second engine usually is felt after 12 to 18 mph and on trials of statring various loads on shap showed this to be the achilles heel for fast WCML use of the older deltics, despite their being a suprluss of them in relation to ECML duties.
In addition EE now had the experience to be able to better design systems to keep power at an efficient 80% + of max rpm and to feed mechanical power into electrical systems in a mutually optimum way. The issue with the turbo deltic engine was that it produced a somewhat sudden acceleration when the turbo boost range was established. In effect this meant that torque loads across the generator and subsequent voltage/amps delivery was problematic on the first test-bed set ups. To overcome this and also to increase overall fuel efficiency, the novel idle injection supression was utilised to maintain a slightly higher idle rpm on 'engine only' select on the main controller. This meant when required to come into power the injectors were swithced in, exhaust mainfold pressure peaked up and the turbo system came in to efficiency immediately...therewith could the clutching system engage the generator and modulate the initial torque rpm delivery. this meant that power was available fast and also too fast for the second engine to be phased in if it were to be operated like a traditional deltic loco.
Characteristically the idle drone of the SDs is replaced by the 'calling whilstle' as the turbo band engages and the locomotive makes progress on both engines. The KV circuits then feed in the power progressively at least as far as first divert, when they either give back dwon to 60% of range or full back down to idle depending on the circumstanes. When the PUs themselves, their electircal and control KV12 system are working then both engines progress within about 5% of rpm from each other and often less than 2% variance. If on the other handone goes astry a little the the KV11 load balancing function detects too much or too little power and insttructs the Kv12s accordingly. It will first try to make a lagging engine catch up, then reduce the other healthy engine to a lower difference and then finally if this new acceleration in harmony fails, it will throw the lagging engine out of circuit and continue with a single unit. All this with no intervention from the driver so far. The driver will however 'see' a warning light appear. However no sound was initially coupled to this, a fact which lead to a bit of head scratching when progress was poor. Usually a glance at the twin circuit ammeter to the right of the displays would reveal the problem, even if they still did not glance alittle further to the fault display panel. In 79-80 not alll ocos where fitted with a repositioned fault panel, but also with a diagnostic programme which will control the eletromechanicals of the 'lagging' or failed engine. For example it firstly allows the engine to rev freely out of connection with the generator to spot fuel, turbo or mechanical failure which all have their own 'footprint' on response.
The KV11 tolerates quite a wider maximum misbalance as it marries in the two ciruits onto the 'main board' as it it refered to by fitters. However in operation those drivers who were Deltic convverts would keep a close eye on the twin needle display to look for misbalances and also to take advantage of spotting each presumed weak field area. Some even placed pieces of tape on the speedo dial and amps needle to show them both when it should cut out and how hard to push the amps needle on the main circuit.
Prior to the 1973 fuel crisis, enquisitive drivers and inspectors would select 'single engine operation' or switch off the actual weaker of the two on the 'main panel' in a station such as penrith or at a slack like over beattock summitt may permit, and see how the loco would perform. Speeds of 112 mph were someetimes noted, and often this was as fast as the "diagram" ( the timetable- the slot in air traffic control terms) would allow before they would be catching up the preceeding train. Under the oil crisis and indeed up to the end of their operations ont he WCML, superdeltic training envouraged the utilisation of single engine running amd a slight modification was made so that the shut down could be operated under notch zero rather than the more time comnsuming 'engine only' . Also as part of this "mod' " the second engine would be switched off under the new circuit upon selection of single engine only- sometimes not to actually produce again due to fault or neglect of the driver to deactivate single running ! This facility extended the use of SDs beyond their initial withdrawal from WCML north area services, allowing them to work Inverness, Ft William, Stranraer and Aberdeen services where 2200hp was enough to deliver timings to a fine diagram, in fact as good as the supposedly more powerful brush type 4.
Traction Motors and Related Systems
The traction motors were specially prepared as a complete divergence fromthe fairly standard units to be found on the later re-classified class 37, class 38, class 50, class 52 and class 55. They were slightly larger and had better ventilation design. Also they had some advanced electircal capacities which are really beyond the scope of this book, but that is to say they would better tolerate the power amp/volt fluctuations of the KV set up, the harsh route and the higher eventual voltage at max speed than the predecessor type. Patents were licensed in from both the GE and GM companies of the USA and siemens of Germany. Despite any complexities, they prove to be pretty much as sturdy as their cousing with better outright performance.
The only weakness in the TMs is being really related to the design brief- to accelerate trains hard and achieve high top speed and rapid pick up from slacks due to signaling. The TMs had a tendecny to overheat when worked hard from standstills or very slow slacks on heavier trains and would often do so upon any signal haults on the steeper gradients of the route north of preston. In fact the control equipment could have been designed to be a lot more conservative in not responding to 'notch 8, gradient on, heavy train on, let's go!! ' driver styles but EE did not want to disappoint in presenting a clean set of heals to both their own deltic build, the committed order for type 4 DP3s and 'super syphons' and the brush/BRCW type 4s and type 5. Also their experience with how hard the EE type 3 was being driven lead them to a falso sense of security of how much 'red zone' amps their new, improved, beefed up TMs would tolerate. In fact it was only when the loco undercarriage and TMs were very dirty or when there was superhumid weather that overheating resulted in flahs overs or incorrectible over-heats. Otherwise EE had been careful to include TM blower start up tests and failure as 'mission critical' to the loco's progress and incorporated auto isloation of the whole affected bogie and appropriately restricted power delivery
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