by Steve Philpott
Around 14 miles north of Grantham along the East Coast Mainline (ECML) lies the Nottinghamshire market town of Newark upon Trent. Although slightly outside of our defined ‘Tracks through Grantham’ (TTG) northern territory, which is Westborough, the journey to Newark Northgate offers passengers a transitional mixture of urban and agricultural scenery. There’s even a tunnel (Peascliffe) and a historic junction (Barkston) on the way, which as we all know was the starting point of Mallard’s epic record breaking run through Grantham on the 3rd July 1938. Fast forward some forty odd years and the same area forms part of the setting for Steve’s latest article, albeit in the opposite direction. Departing from Grantham our train(s) will be hauled by a ‘Deltic’ (class 55).
As an introduction to the ‘Race to Newark’ and for those readers not too familiar with the ‘Deltics’ (surely no one?) we have some background history on our main Deltic page here. There’s a potted history of the class, outlining how their introduction in the early 1960s created a revolution in travel on the ECML comparable with the advent of the streamlined express steam-hauled services of the mid-1930s.
Using his unique blend of personal observation with a sprinkling of technical background Steve looks back at a selection of his own Deltic runs diligently recorded on the stretch of line between Grantham & Newark. These recordings were made on the King’s Cross to York / Hull semi-fast services towards the end of the Deltics B.R. careers.’
The ‘Race to Newark’ experienced and recorded by Steve Philpott
After the May 1978 passenger timetable change, the up to now ubiquitous Deltics were partially displaced from the crack ECML expresses by the new Inter-City 125 (or HST) fleet. This resulted in two of the King’s Cross to York semi-fast services being diagrammed for these magnificent locomotives. The early examples of this ‘new service’ were as follows:-
1L15. The 16.08 King’s Cross to York, calling at Grantham at 17.36½ to 17.38½ and reaching Newark at 17.50½ (12 minutes)
1L18. The 18.09 King’s Cross to York, calling at Grantham at 19.30 to 19.32 and reaching Newark at 19.44 (12 minutes)
Both turns came off ‘express’ diagrams at the London end, i.e. 1A15 the 10.20 Newcastle to King’s Cross for 1L15 and 1A17 which was the 12.50 ex Leeds City for 1L18. Both trains had full dining facilities on board and as a result were given a D315 timing load (see note below*) within the 1978 YA Working Time Table (WTT). This meant that unlike their successors (from May 1979), both 1L15 and 1L18 were awarded 12 minutes start to stop, from Grantham to Newark Northgate. I mention these two trains merely as an introduction as to how the Deltic hauled semi fast service evolved over the next three years, with some very fast times and speeds being recorded, but they are not the subject of my analysis here.
*A NOTE ON TIMING LOADS:- As a general rule of thumb loco hauled services would have something like D280 or D315 etc. where D is the traction (diesel) and 280 or 315 is the weight. This is based on using a standard approximation of say 35 tonnes a coach. So an 8 coach train x 35 tonnes would be D280 and a 9 coach train would be D315, plus the loco length. Of course these are maximum weights as the train may be running lighter.
The following year’s timetable change (May 1979) saw the introduction of the full HST service on all of the long haul and fast services along the ECML through Grantham. That was pretty much it for class 55s, save for a couple of turns that had slipped through the net and the upgraded semi-fast service. Incidentally, the latter became a real boon for us Deltic followers as we now had these machines booked to stop every two hours at Grantham in each direction and every day of the week! However, in saying that, one turn that did stand out, although it didn’t stop at Grantham, was the down Hull Executive, the 17.05 King’s Cross to Hull, which was booked to complete the 138.61 miles from London to Retford in 91 minutes, making it the fastest ever loco hauled passenger train in the UK! However, I digress, that will of course be included in a future Deltic story!
After the May 1979 timetable alteration the programming of locomotives on these enhanced semi-fast services also changed. They effectively became completely enclosed diagrams during the day with them still escaping to Scotland on various overnight services; we still had such things running in the late 1970s! As the coaching stock sets were rotated between the semi-fast turns with almost total exclusivity, they were trimmed down to load 8, with one catering vehicle included and given a blanket timing load of D280. This allowed the timing people to speed things up a little, by shaving half a minute off the Grantham to Newark start to stop schedules for all of these turns. The other effect of the changes brought in with the May 1979 timetable upgrade was that reporting numbers were altered. For example, 1L15 became 1L44 and 1L18 became 1L45. This was to accommodate the HST services on the Leeds turns which retained the low numbered ‘L’ identities.
Deltic hauled semi-fast services were now booked to depart King’s Cross at 5 minutes past each even hour throughout the day for either Hull or York with the exception of 1L42, the 12.20 to York. This was (unusually) a limited stop service calling at Peterborough and Doncaster only. The other exception was 1D08, the 19.40 to Hull Paragon. By now all of these turns were crewed by a mixture of London, Doncaster and York men, producing, from a timing point of view, various rates of success.
1L44 was a York turn and a small group of these men were obviously ‘up for it’ for I timed this particular train on a very regular basis for three years, resulting in some ‘very interesting runs’ and not just between Grantham and Newark!
We’re almost ready to embark on the ‘RACE TO NEWARK’ but first, let’s have a look at the stretch of line between Grantham and Newark.
Departing from Grantham station the down main line is on a banked curve to the right. This undulating section starts with a falling gradient of 1 in 330 before a rise to 1 in 330 followed by another fall to 1 in 240 for around a quarter of a mile. Having left the town behind our train will head out into the countryside on a long level straight and in the far distance the wooded higher ground above Peascliffe Tunnel is visible on the horizon.
A few minutes later, after passing under Belton Lane Bridge on a falling gradient of 1 in 440, we will enter a fairly shallow cutting before plunging into the depths of the tunnel. Emerging from the cool darkness we burst out of the northern portal of Peascliffe and back into daylight. A brief swish from above means we have just gone under Gadd’s Lane Bridge and to our left we have Jericho Woods with the line at this point on a falling gradient of 1 in 200. Soon we leave Jericho Woods behind and tear past the site of the former Barkston Station.
The line is now curving slightly to the left and our train soon goes over the Sleaford to Nottingham route, which passes underneath the ECML at this point. Now on a short section of fairly straight track we clatter over a viaduct spanning the river Witham below. Next up is the old ‘Frinkley Lane’ crossing where the line again leans to the left on a still falling gradient of 1 in 300. The road bridge from Marston to Gelston, situated just to the north of the site of the former Hougham station, is passed in a flash. The line here straightens after the curve and we approach the road bridge from Hougham to Brandon.
The falling gradient has now eased to 1 in 550 and we find ourselves in open countryside on the long straight towards Claypole. The line here is level for a while before another slight rise over a short distance and then after reaching its peak, it falls again to 1 in 220 just before Claypole itself.
Once past Claypole the line ahead changes from 1 in 220 to 1 in 330 before levelling again just before Balderton Box, situated on a falling gradient of 1 in 330. After nearly a mile of level track the line starts to rise again at 1 in 330 for about half a mile. A short level section is followed by the decent into Newark at 1 in 300 before levelling out again near to Sleaford Road Bridge and finally arriving at Newark Northgate Station.
Man and machine in Harmony
Contrary to what other people might allude to, I found that individual Deltic locomotives were all pretty much on a par with each other regarding performance. One of the most important factors in all of this was the driving technique of the man in ‘the seat’. From my own reasonable experience, if both man and machine were on good form, with a standard 8 coach 280 tonne train in tow it would be reasonable to expect to go through the first electrical field divert* at 50-odd mph by the time we’d got to Diana Bridge which spanned the old A1 at Gonerby Hill Foot just north of Grantham Station. The second divert* was at around 80 mph just before plunging into Peascliffe Tunnel. The divert* itself could be ascertained by the trained ear, as a brief drop in engine tone at full power and it was quite discernible to someone that knew what they were listening for. Likewise, when power was eased, an experienced traveller would hear the roar of the Napier engines drop and feel the coaches ‘run on’ to the locomotive ever so slightly even at 100+ mph! Another factor that played an important part in the constant fast running on this stretch of the ECML was the terrain, with favourable gently dropping gradients of between 1 in 200 to 550, save for a couple of very brief rises, all the way to the Trent Valley beyond Newark as the gradient profile and description above shows.
Grantham to Newark: my actual timings
I have selected eight ‘identical’ runs between Grantham and Newark that took place in 1981 over a period of just under 3 months. They were selected due to their individual actual timings and their identical booked trailing loads and motive power, i.e. Class 55 Deltics! This period produced runs with Class 55s at their optimum performance values even though the class was within 4 months of total withdrawal from capital service! The data collected illustrates that, driven with skill and enthusiasm, which indeed they were, these locomotives were still a match for virtually anything on the network and the values shown go a long way to prove that. It is so evident that even in their twilight years the class as a whole were capable, right up to their last days in service, of performing at well over 110% of their design capability.
As can be seen from table ‘A’ below the passing time at Barkston South Junction has a timing spread of 12 seconds, Hougham has 14 seconds and Claypole 13 seconds. However, taking the intermediate times between the three timing points at full speed the following results are clear - Barkston South Junction to Hougham; spread is 3 seconds and Hougham to Claypole has widened out to 15 seconds. This data of course is totally dependent on the maximum speeds attained on each section and illustrates the advantage of a slightly falling gradient on this section of the line, as the gradient profile above shows. It should be remembered that these were 100 mph locomotives and the fact that they were able to maintain speeds in excess of +10 to 15% of design capability illustrates their collective prowess in high speed performance. The lower part of table ‘A’ illustrates the Effective Drawbar Horsepower** (see explanation below) calculated on each separate section on each individual run.
**Effective Drawbar Horsepower (EDHP) is the actual measured power, after various losses within the vehicle have been calculated, through the couplings as opposed to Brake Horsepower (BHP) which is the pure rating figure attributed to the vehicle’s power unit(s) before any such calculated losses. EDHP is usually around 15% below the quoted BHP figure.
During the 3 years or so that Grantham in particular was blessed with these Deltic hauled trains I was working shifts as part of my time with the Royal Mail. This meant that I was able to take full advantage of this service. I was able to time many hundreds of runs on both the ‘Up’ and ‘Down’ roads with 20 of the 22 class members (unfortunately St. Paddy and Nimbus had already been taken out of service) and they never failed to deliver and excite! I never tired of listening to the awesome roar of the twin Napiers, especially at full chat, and the majestic aura of power that these wonderful machines exuded. They were the true successors to the marvellous Pacifics that had gone before on this line and were held in very high regard by virtually everyone that came into contact with them. Deltic hauled runs with speeds that surpassed their ‘maximum’ figure were commonplace, with some being quite exceptional!
Let’s look at some of the detail by making reference to the table shown above. The table covers eight particular runs logged, of which two are especially quite remarkable for entirely different reasons. Note: The distance from Claypole to Broad Fen Lane (Balderton) Level Crossing is 1.54 miles.
In the first column we have 55019 ‘Royal Highland Fusilier’ on 1L44 recorded on 2nd July 1981. A maximum speed of 118½ mph was attained near Broad Fen Lane, Balderton, with the average over a 3 mile stretch, either side of Claypole, being an incredible 117mph! However, two days later, on the same train she was recorded in the same place doing 117mph again and on subsequent occasions, in various other places, for the ensuing two weeks, at similar speeds before being stopped for a ‘B-exam’ at her home depot of York. It was, at the time, believed, that during her previous ‘D-exam’, at York TMD, a few weeks before, she had received new wheelsets and the speedometer had not been recalibrated accordingly to reflect this and so, as a result, was probably reading about 15 mph ‘slow’ a good excuse for a bit of excess speed!
In the last column (8) of the table the other run worthy of mention from the eight illustrated took place on 24th September 1981 with 55018 ‘Ballymoss’, again on 1L44. This time a maximum of 112½ mph was recorded in the Claypole area but what made this run particularly special was the approach to Newark where it should, of course, have stopped. Once again, I had the timing gear out and I became a bit suspicious when, as we were approaching Bullpit Lane level crossing at Balderton, the power was still on and I was recording 110 mph at this fairly late stage! As 1L44 hurtled towards the next level crossing, at Barnby, the power was finally shut off, but we were still doing 102½ mph as 55018 ‘Ballymoss’ hammered over the road with the brakes subsequently being applied a little after. It’s the only time, in all my years of train travel that I can say that I’d witnessed a full emergency brake application as we bombed towards Northgate station. We passed under Sleaford Road bridge still at around 90 mph! We entered the platforms, still in full emergency braking, doing 67 mph, passing in 10 minutes 16 seconds. With our velocity rapidly decreasing and ballast and debris being thrown up from the ‘four-foot’ in our wake, 1L44 eventually came to a shuddering halt nearer to the Newark flat crossing than the platforms in 10 minutes 43 seconds! This still stands today as my fastest diesel hauled Grantham to Newark start-to-stop time! Anyway, after about a minute or so ‘Ballymoss’ propelled the train back into platform 1 at Northgate, followed by a subsequent ‘please explain’ from Bob Archer, who was the duty station supervisor. It was obvious, however, that the Driver was not in a mood to cooperate and as Bob attempted to board the loco he was told in no uncertain terms not to do so! Anyway, we were quickly away again, after this unplanned manoeuvre, and it was soon clear that both locomotive and Driver were unperturbed by recent events as I recorded further speeds of 110 mph+ before Retford!
Note * In the last column (8) above, the Newark platforms were timed as passing in 10 minutes & 16 seconds!
Finally, for technical minded readers:-
On a diesel electric locomotive (such as a Deltic) its traction motors are of a DC (Direct Current) drive system and are effectively large electro magnets whose behaviour can be altered/ regulated by changing the voltage passing through the field windings if they are of ‘traditional’ design as some later developments using SEPEX (Separation Excitement) control are somewhat different. Typically, a locomotive develops a maximum tractive effort (torque) at around 13 mph after which the speed increases and the current demand falls.
All DC traction motors develop back EMF (Electromotive Force) which is the motor acting as a generator and effectively countering the power going into it, so the current falls to a very low point but the power unit may be at full power which means the that the generator cannot spin any faster to produce more volts. Therefore the motors' behaviour has to be altered to get them to spin to the required velocity by diverting the field voltage through a set of resistors in a process known as ‘field diversion’ which is, in principle, the same as changing gear on a road vehicle.
A DC traction drive system will start with motors connected in series (with additional resistance in circuit to reduce the starting current) and as the motors speed up these resistors will be switched out until just the motors are connected across the D.C. supply. To increase the speed further the motors are then reconfigured so they become connected in parallel to the supply and this is, effectively, the first divert.
However, when, subsequently, the parallel motors have reached their full speed (dictated by electromagnetic forces balancing out in the motor) then speed can be increased further by maintaining full current through the armature but switching in a ‘divert’ circuit so that only a proportion of the current flows in the field winding. This is referred to as ‘weak field’ operation. This, then, becomes the second field divert.
On a ‘classic’ diesel electric locomotive, such as a Deltic, the Driver would watch his ammeter closely, as with low speeds and little, or no back EMF generated by the traction motors (which will be stationary, or close to it) the amps can rise very quickly, potentially leading to an overload and/ or wheelslip, therefore, the controller would be opened to about notch-2 on starting away being ready to ease back if the needle went through the yellow section, on the ammeter, and touched red.
However, as the speed increases and the build-up of back EMF starts to reduce the amps through the traction motors, the amps shown on the ammeter would start to fall and the Driver could safely apply more power to increase speed. When the field diverts occur, usually at 48 to 52 mph and 78 to 82 mph the load regulator should automatically reduce the fuel delivered to the injectors as they cut in, enabling the load to fall off, albeit for a second or so, with the process then starting all over again at this higher speed step.
As technology developed aids such as anti-wheelslip detectors were fitted which sensed any drop in load over the traction motors and, subsequently, cut the output to them until the slip had been corrected.
The term back electromotive force (EMF) is also commonly used to refer to the voltage that occurs in electric motors where there is relative motion between the armature and the magnetic field produced by the motor's field coils, thus also acting as a generator while running as a motor.
You may also see on some loco hauled services something like D280, in which D denotes the traction (diesel) and 280 is the weight. In this case, (D280) uses a standard approximation of 35 tonnes per coach x 8 coaches, resulting in 280 tonnes plus the loco length. Although that's not entirely accurate, as:
A) It's a maximum weight, and the train may be running lighter
B) At least for older timing loads, D280 would be a specific locomotive hauling 280 tonnes. A less powerful locomotive would haul a smaller number of coaches to match the same timing load, and a more powerful locomotive (or locos in multiple) may haul more. Looking at a 1971 WTT, D280 could therefore be anywhere between 85 tonnes (Class 20) to 380 tonnes (Class 50 with ETH disabled)
Steve Philpott - October 2020