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The SER Q class was a class of 0-4-4T steam locomotives of the South Eastern Railway. The class was designed by James Stirling and introduced in 1881.[1]
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Transcription
The cardiac conduction system consists of the following components: - The sinoatrial node, or SA node, located in the right atrium near the entrance of the superior vena cava. This is the natural pacemaker of the heart. It initiates all heartbeat and determines heart rate. Electrical impulses from the SA node spread throughout both atria and stimulate them to contract. - The atrioventricular node, or AV node, located on the other side of the right atrium, near the AV valve. The AV node serves as electrical gateway to the ventricles. It delays the passage of electrical impulses to the ventricles. This delay is to ensure that the atria have ejected all the blood into the ventricles before the ventricles contract. - The AV node receives signals from the SA node and passes them onto the atrioventricular bundle - AV bundle or bundle of His. - This bundle is then divided into right and left bundle branches which conduct the impulses toward the apex of the heart. The signals are then passed onto Purkinje fibers, turning upward and spreading throughout the ventricular myocardium. Electrical activities of the heart can be recorded in the form of electrocardiogram, ECG or EKG. An ECG is a composite recording of all the action potentials produced by the nodes and the cells of the myocardium. Each wave or segment of the ECG corresponds to a certain event of the cardiac electrical cycle. When the atria are full of blood, the SA node fires, electrical signals spread throughout the atria and cause them to depolarize. This is represented by the P wave on the ECG. Atrial contraction , or atrial systole starts about 100 ms after the P wave begins. The P-Q segment represents the time the signals travel from the SA node to the AV node. The QRS complex marks the firing of the AV node and represents ventricular depolarization: - Q wave corresponds to depolarization of the interventricular septum. - R wave is produced by depolarization of the main mass of the ventricles. - S wave represents the last phase of ventricular depolarization at the base of the heart. - Atrial repolarization also occurs during this time but the signal is obscured by the large QRS complex. The S-T segment reflects the plateau in the myocardial action potential. This is when the ventricles contract and pump blood. The T wave represents ventricular repolarization immediately before ventricular relaxation, or ventricular diastole. The cycle repeats itself with every heartbeat.
Construction
Prior to the appointment of James Stirling as Locomotive Superintendent of the South Eastern Railway (SER) in 1878, that railway possessed only a small number of tank locomotives suitable for the London suburban passenger services. There were twelve 0-4-2WT of the 205 class (later G class) dating from 1863–64; seven 0-4-4WT of the 235 class (later J class) dating from 1866; six 0-4-2WT of the 73 class (later H class) dating from 1867–69; and nine 0-4-4T of the 58 class (later M class) dating from 1877–78.[2]
The SER had opened a connection to the London, Chatham and Dover Railway in June 1878 giving access to Blackfriars station, the Widened Lines and thus the Great Northern Railway. Tender locomotives were not suitable for working this route, and nor were many of the existing tank engines which were not powerful enough. As a stop-gap pending the preparation of a new design, the SER purchased three newly-built Metropolitan Railway B Class 4-4-0T locomotives from that railway in April 1880, which were used on SER services from Woolwich Arsenal via Blackfriars and Finsbury Park to Alexandra Palace. They were sold back to the Metropolitan Railway in November 1883.[3][4]
In his previous post with the Glasgow and South Western Railway (G&SWR), Stirling had designed an 0-4-4T for suburban passenger services, the G&SWR 1 class. He kept copies of the drawings and used these as the basis for a new class for the SER, which became the SER Q class. One hundred and eighteen locomotives were built between 1881 and 1897, of which 60 were built by Neilson and Company; 48 by the SER at Ashford Works; and ten by Sharp, Stewart and Company.[5]
| Years | Builder | Quantity | SER Nos. |
|---|---|---|---|
| 1881 | Neilson | 10 | 303–312 |
| 1881–82 | Ashford | 12 | 177, 178, 158, 161, 162, 164, 5, 181, 27, 182, 180, 184 |
| 1882–83 | Neilson | 10 | 319–328 |
| 1885 | Ashford | 2 | 329, 330 |
| 1887 | Ashford | 10 | 129, 193, 237, 239, 40, 26, 12, 72, 200, 235 |
| 1888 | Ashford | 5 | 16, 81, 83, 141, 173 |
| 1889 | Ashford | 4 | 23, 85, 220, 82 |
| 1889 | Neilson | 10 | 343–352 |
| 1891 | Neilson | 15 | 354–368 |
| 1891 | Ashford | 6 | 58, 134, 146, 73, 115, 224 |
| 1892 | Ashford | 3 | 135, 136, 138 |
| 1893–94 | Sharp Stewart | 10 | 399–408 |
| 1894–95 | Ashford | 6 | 6, 50, 95, 76, 168, 169 |
| 1897 | Neilson | 15 | 410–424 |
Most were built with tall chimneys giving an overall height of 13 ft 3+1⁄2 in (4.051 m) and two injectors for the boiler feed. The 1881–82 Ashford series were built for working through the Snow Hill tunnel and the tunnels of the East London Railway, and so were provided with condensers and short chimneys giving an overall height of 12 ft 6 in (3.81 m), one injector being omitted and a boiler feed pump fitted instead.[6]
The first 34, built between 1881 and 1885, had bogies of wheelbase 4 ft 10 in (1.47 m) having wheels of 3 ft (0.91 m) diameter. These bogies had a fixed centre pin and were troublesome, and so beginning in 1887 new locomotives had a better bogie design based upon that of the contemporary 4-4-0s of the F class. This had 13⁄16 in (21 mm) side play, its wheelbase being 5 ft 4 in (1.63 m); and after four of these had been built using the 3-foot wheel, subsequent locomotives had the bogie wheel diameter increased to 3 ft 9 in (1.14 m) to make them fully interchangeable with those of the F class.[7]
Rebuilding
The locomotives passed to the South Eastern and Chatham Railway in 1899 and 55 were rebuilt by Harry Wainwright to class Q1 between 1903 and 1919.
Numbering
Thirty-two unrebuilt locomotives survived into Southern Railway ownership on 1 January 1923 with random numbers between 6 and 424. All had been withdrawn by 1929.
| Year | Quantity in service at start of year |
Quantity withdrawn |
Locomotive numbers | Notes |
|---|---|---|---|---|
| 1925 | 32 | 1 | A346 | |
| 1926 | 31 | 15 | A40, A72, A73, A82, A135, A220, A237, A345, A352, A358, A360, A405, A417, A418, A422 |
|
| 1927 | 16 | 11 | A6, A26, A136, A169, A235, A356, A399, A410, A414, A421, A424 | |
| 1928 | 5 | 3 | A23, A173, A401 | |
| 1929 | 2 | 2 | A349, A368 |
References
- ^ Casserley & Johnston 1974, p. 42.
- ^ Bradley 1985, pp. 121, 123, 125, 135–6, 160.
- ^ Bradley 1985, pp. 160, 217–8.
- ^ Goudie 1990, pp. 14, 24.
- ^ Bradley 1985, p. 160.
- ^ Bradley 1985, pp. 160–1.
- ^ Bradley 1985, pp. 160, 162.
Bibliography
- Ahrons, E.L. (1926). The British Steam Railway Locomotive. Ian Allan.
- Bradley, D.L. (September 1985) [1963]. The Locomotive History of the South Eastern Railway (2nd ed.). London: RCTS. ISBN 0-901115-48-7. OCLC 642415860.
- Casserley, H.C.; Johnston, S.W. (1974). Locomotives at the Grouping 1, Southern Railway. Ian Allan. ISBN 0-7110-0552-4.
- Goudie, Frank (1990). Metropolitan Steam Locomotives. Harrow Weald: Capital Transport. ISBN 1-85414-118-X.
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This page was last edited on 21 February 2024, at 16:05