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British Rail Class 144
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British Rail Class 144
The British Rail Class 144 Pacer is a retired class of diesel multiple unit (DMU) passenger trains built at Derby between 1986 and 1987. British Rail, seeking to procure improved derivatives of the earlier Class 141, placed an order with the manufacturers British Rail Engineering Limited (BREL) and Walter Alexander to construct their own variant, the Class 144. A total of 23 units were constructed. All units were retired from main line service by 2020, though the majority of the units have been acquired for preservation on heritage railways and for other uses. As of December 2022, 19 out of the 23 units have been purchased following withdrawal, of which 14 units are in operational condition.
By the beginning of the 1980s, British Rail (BR) operated a large fleet of first generation DMUs, which had been constructed in prior decades to various designs. While formulating its long-term strategy for this sector of its operations, BR planners recognised that there would be considerable costs incurred by undertaking refurbishment programmes necessary for the continued use of these aging multiple units, particularly due to the necessity of handling and removing hazardous materials such as asbestos. In 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 (procurement) and ongoing (maintenance & operational) costs, while the second was a more substantial DMU that could deliver superior 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 Class 150 and the wider Sprinter group 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. As such, work to progress both approaches was 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 as the Class 140, that was constructed between 1979 and 1981. This prototype was introduced with much fanfare during June 1981. Initial testing with the Class 140 uncovered several issues, such as difficulty detecting the type via track circuits; this was reliably resolved by swapping 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, which was 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 primarily goal of the type.
The Class 140 was viewed to be an overall success, and thus BR issued an order for an initial production model, designated Class 141, to British Leyland during 1984 with production commencing thereafter. During its early years of service, the Class 141 experienced numerous issues, particularly with the transmission and ride quality; work undertaken at BR's direct 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 Class 143 respectively. Thereafter, another and final Pacer model would be ordered, this being the Class 144.
A total of 23 Class 144 units were constructed. The units have a maximum speed of 75 mph (121 km/h) and are externally similar to the earlier Class 143 Pacers, sharing a near-identical body built by Walter Alexander. The first thirteen of the class – numbers 144001 to 144013 – are two-car units, while the remaining ten – 144014 to 144023 – have a third vehicle that was added later. These ten Pacers are the only ones to use intermediate vehicles.
Units are formed of two driving motors, one of which contains a toilet. The three-car units have an additional intermediate motor. All vehicles have standard-class seating only. The technical description of the formation is DMS-(MS-)DMSL. Individual vehicles are numbered as follows:
As originally built, the traction arrangement of the Class 142 consisted of a 200 horsepower (150 kW) 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. Starting in the early 1990s, every member of the class was mechanically upgraded due to the original parts being determined to be a major source of unreliability. The most substantial change was the replacement of the Leyland-built engine with a more powerful Cummins LTA10-R as well as the original mechanical transmission being substituted for a Voith hydrokinetic unit.
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British Rail Class 144
The British Rail Class 144 Pacer is a retired class of diesel multiple unit (DMU) passenger trains built at Derby between 1986 and 1987. British Rail, seeking to procure improved derivatives of the earlier Class 141, placed an order with the manufacturers British Rail Engineering Limited (BREL) and Walter Alexander to construct their own variant, the Class 144. A total of 23 units were constructed. All units were retired from main line service by 2020, though the majority of the units have been acquired for preservation on heritage railways and for other uses. As of December 2022, 19 out of the 23 units have been purchased following withdrawal, of which 14 units are in operational condition.
By the beginning of the 1980s, British Rail (BR) operated a large fleet of first generation DMUs, which had been constructed in prior decades to various designs. While formulating its long-term strategy for this sector of its operations, BR planners recognised that there would be considerable costs incurred by undertaking refurbishment programmes necessary for the continued use of these aging multiple units, particularly due to the necessity of handling and removing hazardous materials such as asbestos. In 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 (procurement) and ongoing (maintenance & operational) costs, while the second was a more substantial DMU that could deliver superior 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 Class 150 and the wider Sprinter group 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. As such, work to progress both approaches was 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 as the Class 140, that was constructed between 1979 and 1981. This prototype was introduced with much fanfare during June 1981. Initial testing with the Class 140 uncovered several issues, such as difficulty detecting the type via track circuits; this was reliably resolved by swapping 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, which was 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 primarily goal of the type.
The Class 140 was viewed to be an overall success, and thus BR issued an order for an initial production model, designated Class 141, to British Leyland during 1984 with production commencing thereafter. During its early years of service, the Class 141 experienced numerous issues, particularly with the transmission and ride quality; work undertaken at BR's direct 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 Class 143 respectively. Thereafter, another and final Pacer model would be ordered, this being the Class 144.
A total of 23 Class 144 units were constructed. The units have a maximum speed of 75 mph (121 km/h) and are externally similar to the earlier Class 143 Pacers, sharing a near-identical body built by Walter Alexander. The first thirteen of the class – numbers 144001 to 144013 – are two-car units, while the remaining ten – 144014 to 144023 – have a third vehicle that was added later. These ten Pacers are the only ones to use intermediate vehicles.
Units are formed of two driving motors, one of which contains a toilet. The three-car units have an additional intermediate motor. All vehicles have standard-class seating only. The technical description of the formation is DMS-(MS-)DMSL. Individual vehicles are numbered as follows:
As originally built, the traction arrangement of the Class 142 consisted of a 200 horsepower (150 kW) 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. Starting in the early 1990s, every member of the class was mechanically upgraded due to the original parts being determined to be a major source of unreliability. The most substantial change was the replacement of the Leyland-built engine with a more powerful Cummins LTA10-R as well as the original mechanical transmission being substituted for a Voith hydrokinetic unit.
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