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Hornby R2338 NE Class A4 Charles H Newton
Review & DCC Decoder installation - Text & photos by Doug Teggin

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Prototype Info: The LNER's Express Pacific designs were probably the most famous of the LNER locomotives.

By the 1930s, the railways were beginning to see increased competition from road and air travel. It was clear that services between the major cities had to be faster, more reliable, and more comfortable.

Sir Nigel Gresley, designer of the A4, traveled on the Fliegende Hamburger and was impressed by the need for streamlining. He calculated that a streamlined and modified A3 design would be able to haul trains of eight or nine carriages at similar speeds.

A series of trials were carried out, to confirm that a modified A3 design would be sufficient. During these, A1 Flying Scotsman broke100mph. With these trials under his belt, the LNER Board gave Gresley the go-ahead to create the "Silver Jubilee" streamlined trains.

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The wedge-shaped streamlining on the A4 was inspired by a Bugatti rail-car which Gresley had observed in France. The design was refined with the help of Prof. Dalby and the wind tunnel facilities at the National Physical Laboratory (NPL) at Teddington.

The LNER publicity machine had a field day with the new streamlined shape. Experimental data showed that a 40% reduction in horsepower was required when powering from 60mph to 150mph. The high speed of 150mph was used to simulate a headwind. This saving ranged from 41hp at 60mph to 639hp at 150mph.

A demonstration run from Kings Cross to Grantham on 27th September 1935 touched 112.5mph. The first service was on the 1st October 1935, hauled by No. 2509 Silver Link. A further three locomotives were built for the Silver Jubilee service to Newcastle. This service was a great success cutting the travel time between Kings Cross and Newcastle down to an amazing 4 hours.

A peak average speed of 125mph was recorded on dynamometer tests - so breaking the world record for steam traction held by the German State Railways (124.5mph) and the British record set by the LMS (114mph). On July 3rd 1938, the locomotive Mallard set a new speed record of 125mph for steam traction on the East Coast Main Line at milepost 90¼.

Over 60 years later, Mallard's record of 125mph still stands.

By the late 1950s, steam was being replaced by diesel power. Although the Deltics proved worthy successors of the A4s on East Coast Mainline express services, other diesel classes were generally very poor and often failed. Hence, the A4s were kept in service until the mid-1960s. The first A4s were scrapped at the end of 1962. These were from Kings Cross and had been directly replaced by the Deltics. The last BR A4 service was on 14th September 1966 between Aberdeen and Glasgow.

Info specific to 4901:
Date Built: 8/6/1938;
LNER No.: 4901;
1946 No.: 5;
BR No.: 60005;
Disposal Date: 1964;
Original Name: Capercaillie;
Second Name: Charles H. Newton (9/1942);
4901 was renamed from Charles H. Newton to Sir Charles Newton on 4th June 1943 to correspond with his knighthood.

Prototype Technical Details

Cylinders (x3):18.5x26in.
Piston Valves:9in. diameter
Boiler:Max. Diameter:6ft 5in
Diagram No.:107
Heating Surface:Total:3325.2 sq.ft.
Firebox:231.2 sq.ft.
Superheater:748.9 sq.ft.
Tubes:1281.4 sq.ft. (121x 2.25in)
Flues:1063.7 sq.ft. (43x 5.25in)
Grate Area:41.25 sq.ft.
Wheels:Leading:3ft 2in
Coupled:6ft 8in
Trailing:3ft 8in
Tender:4ft 2in
Tractive Effort:35,455lb (@ 85% boiler pressure)
Total Wheelbase:60ft 10.625in
Engine Weight:102 tons 19cwt (full)
Max. Axle Load:22 tons

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Above you see the close-coupled tender.
Above, a little animation showing the cab vents that open and close adding a little more light and air into the hot cab.

Wow, just look at the detail of the cab below left. The dials are visible and control valves with their pipe work are individually detailed and painted. A driver and fireman would look good in here.

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Length: 291mm;
Running number: 4901 'Sir Charles Newton';
Livery: Wartime black;
Period: 1943;
Features: Sprung buffers, cab and tender detail, semi fixed rear bogie, DCC ready, NEM couplings;
Finish: Pristine;
Motor: Five pole skew wound loco drive;
Purpose: Express passenger.

Additional Production Notes

Only suitable to run on second radius curves or greater; DCC Ready; NEM Couplings.

Suitable Rolling Stock:
R4170A LNER 61ft 6in Corridor Brake Coach,
R4171A LNER 61ft 6in Corridor 1st Class Coach,
R4172A LNER 61ft 6in Corridor 3rd Class Coach,
R4173A LNER 61ft 6in Buffet Car,
R4174A LNER 61ft 6in Corridor 1st Class Sleeper Coach.

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The imposing aero dynamic front-end of the A4 with it's 'Pristine' finish. A whistle in front of the double Kylchap chimneys.

When it came out in the 1930's the streamlined shape caused such a fuss with train aficionados.

The sprung metal buffers help absorb impact. Appreciate the metal handrails that follow the curve of the locomotive. Just look at those curves going around the sides.

I appreciate that there is no coupler on the front. This loco pulls trains, it doesn't push and it doesn't run backwards.

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Under the tender. The locomotive picks up current from the track from its wheels with additional pick up from the tender making for very sure electrical connection. The drawbar pin is conductive and supplies current from one side, the plate above the pin, supplying the other.

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Fixed flangeless supporting wheels of the rear axel allows the locomotive to corner more easily. Scale flanged wheels are provided in the box if preferred.

Notice the connectors that take the current from the tender. Due to these connectors, when running DCC, always set the tender on the track attaching it to the locomotive with the DCC power turned off otherwise a short could occur. An isolated track section for setting locos on the track is a good idea.

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Detail of the large driven running wheels on the locomotive. Note the detailed sanding pipes and brake pads and linkages.

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DCC Decoder Installation

Follow the supplied instructions to take the loco apart. The process is quite fiddly as some of the push rod mechanics have to be dismantled. Use bubble wrap or a soft surface to support the loco whilst it's upside down. You don't have to force anything - if you do it right, it comes apart easily.

I installed a Arnold Digital 81201 decoder into the Loco. As there are no extra functions required by the locomotive a simple, but robust decoder is fine. The 81201 can handle 1.5 amp. The A4 model draws 0.15 amp when rolling by itself; 0.25 amp when held stationary at the buffers, but with wheels freely sliding on the track; and 1.3 amp with the motor stalled (don't try this unless your decoder can handle the current. The locomotive (with tender) can pull 1.68 kg (6 x 150g coaches + 6 x 130g coaches).

The installation was simplicity itself as the 8-pin NEM-plug just popped into the NEM 652 (NMRA Medium) socket that is supplied, protected by a blanking plug. Make sure the orange wire is aligned with the hole #1 indicated on the socket.

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Note: The TV interference suppression capacitor has to be removed for DCC use. A capacitor is only needed for conventional operations to prevent radio interference. With DCC operation a capacitor corrupts the data format and the error free data transfer is disturbed. A snip with a small cutter does the job. Make sure the ends are insulated if exposed.

The DCC chip sits comfortably on the front block. There is plenty of space within the boiler enclosure for even for the biggest chips. Double-sided tape keeps the decoder secure on the front block. Tape everything in place with black electrical tape and close up the body.

I suppose if you could get a narrow speaker, you could even fit a sound chip in there. Otherwise the tender has plenty of space for a speaker and sound decoder. The tender is opened by removing the NEM coupler, unscrewing the screw beneath it and un-clipping the front of the tender body from the chassis.

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DCC CV Settings for the A4 Locomotive
(The loco number)
CV22Minimum Speed
(V Min at step 1)
CV34Acceleration delay
CV44Brake Delay (0-15)
CV5200Max speed (V High)
CV680Acceleration Curve
(V Mid)
CV9216PWM frequency (69Hz)
CV292Decoder Configuration
CV490Decoder specific values
CV5020Decoder regulation
The rest of the CV's are left untouched (factory default).

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Note: This locomotive does not have lights.

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Programming done and the locomotive runs very smoothly. The max speed is set slightly higher than my other locomotives as the A4 was the fastest of them all. Under DCC control, it moves off on the first speed step, without any jitter or hesitation. If you're used to older models that clatter down the track, you'll be surprised at the quietness of this model. It is so quiet that it needs a sound decoder. I'm sure I'll add one soon.

A very elegant model indeed. The A4 majestically moves off down the line, it's valve gear moving to a mesmerizing rhythm, in sync with the great '6ft 8in' driving wheels. It's a very animated model and would add a very interesting focus to any layout.

- April 2005

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All text, photos & graphics ©2005 Doug Teggin - All rights reserved.
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