page_title: British Rail Class 42
section_title: Service
hierarchical_section_title: British Rail Class 42 / Service
caption_attribution_description: English: A Class 42 Warship and a BR Class 5 4-6-0 at London Waterloo, 1967
context_page_description: British Railways' Class 42 Warship diesel-hydraulic locomotives were introduced in 1958. It was apparent at that time that the largest centre of expertise on diesel-hydraulic locomotives was in West Germany. The Western Region of British Railways negotiated a licence with German manufacturers to scale down the German Federal Railway's "V200" design to suit the smaller loading gauge of the British network, and to allow British manufacturers to construct the new locomotives. The resultant design bears a close resemblance, both cosmetically and in the engineering employed, to the original V200 design. Warship locomotives were divided into two batches: those built at BR's Swindon works were numbered in the series D800-D832 and D866-D870, had a maximum tractive effort of 52,400 pounds-force and eventually became British Rail Class 42. 33 others, D833–D865, were constructed by the North British Locomotive Company and became British Rail Class 43. They were allocated to Bristol Bath Road, Plymouth Laira, Newton Abbot and Old Oak Common.
  Two Class 42s are preserved, D821 and D832.
context_section_description: The D800s were originally intended for the Paddington–Birmingham Snow Hill route and tests proved that their extra weight and power allowed them to run to a two-hour schedule with 368 tons in tow: one coach more than a Class 40 could manage. These plans were put back when Paddington became the temporary London terminus of choice for Birmingham during the early 1960s, whilst BR's preferred route from Euston via Rugby was electrified. Loads of greater than 370 tons would be required and the service remained steam-hauled until the advent of the more powerful Class 52 Western diesel-hydraulic locomotives. The first service route for the class therefore became Paddington–Penzance, either via Swindon and Bristol, or via Newbury and Westbury on the "Berks and Hants" route. This allowed for elimination of steam on the difficult-to-operate railway west of Newton Abbot. In October 1958 D800 became the first locomotive to take up the class's new diagram of the up Cornish Riviera Express (Penzance to Paddington), the 18:30 Paddington–Bristol and the 21:05 Bristol–Plymouth – the last part of the diagram allowing the locomotive to return to the brand new depot at Laira in Plymouth once this was fully operational in 1961.
  The maximum speed of the D800 class was officially 90 mph (140 km/h) but this could not be rigidly enforced because the transmissions could not be precisely governed. 102 mph (164 km/h) was recorded by D801 in private tests during 1959, albeit on a downgrade. The summer of 1959 saw 100 mph (160 km/h) service trains diagrammed for D800s with the Paddington–Bristol "Bristolian" set a schedule of 100 minutes. The outward journey via Bath required an average speed of 71 mph (114 km/h) and the return journey via Badminton averaged at 70.6 mph (113.6 km/h). For a very brief period the D800s achieved both the schedule and more with D804 exceeding 100 mph (160 km/h) three times on one early run from Bristol. This was soon ended when the Western Region's civil engineers imposed a blanket 90 mph (140 km/h) maximum speed on all the Region's main lines, where for five years there had, uniquely to BR at the time, been no restrictions at all. The root cause of this worry was the effect of small-diameter powered wheels carrying far more weight per inch of tread than those of a steam locomotive. These concerns arose particularly from experiences in the United States of America although the significant rail damage reported there was mostly caused by wheel sliding under braking with heavy trailing loads which were very unlikely to occur on BR. With the benefit of modern hindsight, it is possible to say that even though the full US experience would not be replicated, "gauge corner cracking" (the formation of microscopic cracks in the rails that was the primary cause of the Hatfield rail crash of 17 October 2000 in the UK) could have been a possibility if the schedules had been adhered to.
  Around this time, several D800 drivers began reporting uncomfortable lurching over points or on poorly maintained track at high speeds. The problem was eventually traced to the novel design of the bogies and their means of attachment to the locomotive bodyshell: it had given the German V200s no trouble because of the 140 km/h (87 mph) speed limit on the German Federal Railway at the time. High speed running magnified the effect of the almost rigid link between body and bogie, and oscillations created in the entire locomotive structure when the wheels hit pointwork or indifferent track made derailment a very real risk as the tyres on the wheels wore down. The D800s were subject to a maximum speed of 80 mph (130 km/h) and although D804 received modified bogies that allowed the top speed to be restored to 90 mph (140 km/h) in 1961, it took until 1963 before the modification was fully tested and all members of the class were modified. The "Bristolian" was decelerated by 5 minutes but an extra stop at Chippenham was inserted so that the drivers practically had no choice but to exceed 80 mph (130 km/h) to keep to time. All speed running ceased after autumn 1
caption: A "Warship" and a BR Class 5 4-6-0 at London Waterloo, 1967
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