British Rail Class 142
Class 142 diesel multiple unit passenger trains were built for British Rail from 1985 to 1987, with a high level of commonality with the widely used Leyland National bus. They are part of the Pacer family of railbuses. The last set was withdrawn from service in 2020.
Background
By the beginning of the 1980s, British Rail operated a large fleet of first-generation diesel multiple units, which had been constructed in prior decades to various designs. While formulating its long-term strategy for this sector of its operations, British Rail planners recognised that considerable costs would be incurred by undertaking refurbishment programmes necessary for the continued use of these ageing multiple units, particularly due to the necessity of handling and removing hazardous materials such as asbestos. In the light of the high costs involved in retention, planners examined the prospects for the development and introduction of a new generation of DMUs to succeed the first generation.In the concept stage, two separate approaches were devised, one involving a so-called railbus that prioritised the minimisation of both initial and ongoing costs, while the second was a more substantial DMU that could deliver better performance than the existing fleet, particularly when it came to long-distance services. While the more ambitious latter requirement would ultimately lead to the development of the British Rail Class 151 and the wider Sprinter family of DMUs, BR officials recognised that a cheaper unit was desirable for service on the smaller branch lines that would not be unduly impacted by lower performance specs or a high-density configuration. Work to progress both approaches was therefore undertaken by BR's research department during the early 1980s.
During this period, a number of prototypes were constructed to explore different designs and approaches for implementing the railbus concept. One such vehicle was a single two-car unit, designated Class 140, built between 1979 and 1981. This prototype was introduced with much fanfare in June 1981. Initial testing with the Class 140 uncovered several problems, such as difficulty detecting the type via track circuits. This was reliably resolved by changing the material of the brake blocks from a composite to iron. Two less easily addressable drawbacks were the high level of noise generated during transit, particularly on older jointed rails, a consequence of the railbus's direct connection between the underframe and suspension with the body that transmitted impact forces across the body. It was also observed that the inclusion of strengthening members in the mass-produced bus body added significantly to the overall production cost, which eliminated much of the cost advantage that was the primary goal of the type.
The Class 140 was deemed an overall success, so BR issued an order for an initial production model, designated Class 141, to British Leyland during 1984. During its early years of service, the Class 141 experienced numerous problems, particularly with the transmission and ride quality; work undertaken by BR resulted in the quick development of numerous improvements to at least partially address these shortcomings. When it came to ordering more railbuses, however, it was decided that instead of placing these follow-on orders for further Class 141, it would be more desirable to procure improved derivatives of the Class 141. Accordingly, BR placed orders for two new models of the Pacer family with separate manufacturers, these being the Class 142 and the Class 143.
Design
The Class 142 shared a high degree of similarity to the design of the Class 141. However, one major area of change is that both the Class 142 and Class 143 featured a noticeably wider body, instead of adhering to the width of the standard bus as per the Class 141; specifically, the width was expanded to the maximum amount permissible to remain within the loading gauge. This resulted in an increased internal area to accommodate passengers within, enabling a three-by-two seating arrangement to be installed for a total maximum capacity of 121 seats per set. The increased seating was particularly useful as, in addition to their use on rural feeder services, the Class 142's use on short range urban services had been foreseen by BR planners. Each unit has a seating capacity of between 102 and 121 passengers per two-car set.Both the bodies and underframes were designed for interchangeability, as had been specified by BR. To achieve this, they were manufactured upon jigs. They had been designed so that the entire body could be replaced during a mid-life refurbishment/reconstruction, and that the replacement body would not be limited to the exact same dimensions either. The underframe area, in addition to its structural role, accommodated all of the propulsion apparatus along with the majority of electrical gear. As a cost-saving measure, the manufacturers were directly to make use of road bus-standard equipment in several areas, including passenger fittings and the general cab layout, along with other areas wherever possible; Unlike the Class 141, which featured automotive-standard wiring for the traction equipment with resulting poor performance, railway-grade wiring for the traction and braking circuits was mandated by BR for both the Class 142 and Class 143 to yield greater reliability.
As originally built, the traction arrangement of the Class 142 consisted of a Leyland TL11 engine, a Self-Changing Gears mechanical automatic gearbox and a Gmeinder final drive unit on each car driving only a single axle. This propulsion arrangement was in part taken from the Leyland National bus, as well as shared with the earlier Class 141. Unlike the Class 141, a microprocessor-based controller for the automatic transmission was used from the onset, allowing the reliability issues posed by defective relay logic and poor earthing present on the predecessor to be entirely avoided. Another improvement was the installation of auto-couplers and auto-connectors that enabled the Class 142 to work in multiple with the Class 150 Sprinter DMUs. The Class 142 is fitted with double-folding external doors, identical to the preceding Class 141. These double-folding external doors were later replaced by dual-leaf inward folding doors. Each car has a fuel capacity of.
Both axles were fitted directly to the chassis rather than being mounted on bogies, unlike traditional DMUs. This uncommon arrangement has been attributed with resulting in the Class 141 units possessing a relatively rough ride, especially when traversing jointed track or points. Their comparatively poor ride quality has been said to be a major factor in the type's general unpopularity amongst passengers. As a positive result from BR's experiences with the Class 141, the Class 142 featured an improved suspension arrangement to enhance passenger comfort, this consisted of a wider spring base and double dampers being installed, features that had been deemed necessary by BR to provide sufficient levels of performance, and had been retrofitted onto all of the older Class 141s as well.
Excessive flange squeal on tight curves has been a problem on many routes operated by the Class 142, caused by the long wheelbase and lack of bogies.
Upgrades and refurbishments
Starting in the early 1990s, every member of the class was mechanically upgraded due to the original parts starting to fail. Accordingly, each car was refitted with a more powerful Cummins L10 series engine – per car, which equals per twin-car unit – and Voith T211r two-stage hydrokinetic transmission, starting with a torque converter which switches to fluid coupling drive once the unit is up to. All units were fitted with new Voith transmission by late 1991 and Cummins engines were fitted between 1993 and 1996 to improve reliability. This change has proven to have been largely successful, although isolated failures have occurred, such as when a Northern Rail unit derailed en route from Blackpool to Liverpool in June 2009 due to a cardan shaft failure.Operations
British Rail Provincial/Regional Railways
From new, some units were painted according to the region they operated in. For example, the first 14 Greater Manchester Passenger Transport Executive sponsored units received GMPTE orange and brown, then the next 13 West Country based units were painted in a Great Western Railway inspired chocolate and cream livery and marketed as 'Skippers'.Canada
Unit 142049 was sent to Vancouver, Canada for Expo 86. The unit retained its Regional Railways livery and ran three trips a day all summer from Abbotsford to New Westminster. In order to operate on Canadian rails, it was equipped with radio and ditch lights, and given the designation RB100 for radio identification.Post privatisation
Northern England
Upon the privatisation of British Rail, the Class 142 fleet was divided between North Western Trains in the North West and Northern Spirit in the North East.Northern Spirit began operations in 1997 and continued until 2000. At this point, parent company MTL ran into difficulties and the company was sold to Arriva, who renamed it Arriva Trains Northern in 2001.
In 1998, ATN swapped seven Class 142s for seven Class 150/2 units from Valley Lines. In October–December 2002, these were swapped for non-refurbished units 142072-77 and 080–3, as 142086-091 had only recently been refurbished by Northern Spirit and Valley Lines wished to start their refurbishment from scratch.
In 2004, First North Western and Arriva Trains Northern were merged into the Northern rail franchise, which inherited a combined fleet of 79 Class 142s.
All 79 Class 142s were painted into the Northern Rail livery. Due to rising passenger numbers in the north of England, some units had been replaced by Sprinter trains.
Five Class 142 Pacers, in service with First Great Western, were returned to Northern Rail in December 2008. The rest returned to Northern Rail by November 2011, much later than originally planned.
Despite being built for branch-line stopping services, the Class 142s were mainly used on urban commuter services in and out of cities like Liverpool, Manchester, Sheffield, Leeds and Newcastle, and were seen on longer-distance services of up to three hours including the 1632 Middlesbrough-Carlisle service nearly ; they had also been used on services between Blackpool North and Chester via Stockport, which ceased to operate in December 2008. All 79 passed with the Northern franchise to Arriva Rail North in April 2016, and any remaining units transferred to the government-owned operator Northern Trains on 1 March 2020.
In June 2020, it was announced that 13 Class 142s would be allowed to re-enter service if necessary, the units being 142004, 018, 023, 058, 065, 068, 070, 071, 078, 087, 090, 094 and 095, which they did on 6 July 2020 following the introduction of a new timetable, due to a need for extra capacity for social distancing during the COVID-19 pandemic, coupled to s so as to avoid needing to be non-PRM modified.
Pacers were withdrawn from Northern Trains on 27 November 2020, the last service being the 16:36 to, operated by 142004.