Rail Projects : The BRE-Leyland Pacers – the dream becomes a nightmare
Another development of the Leyland/British Rail partnership was the Rail bus. This time it all came to fruition for BL in a period when the bus market was dying. But this time, it got nasty, and had it not been for the Swedes, Leyland would have most certainly been sent into bankruptcy.
Story: Mike Humble
Far from being put off by the failure of the APT, British Leyland entered into another engineering project with British Rail Engineering Ltd (BREL) to joint develop a commuter-style rail bus which would replace the elderly yet stalwart diesel multiple units (DMU) of which some classes dated back to the 1950s. Leyland had supplied engines for BR for many years with DMUs and these were powered by either AEC or Leyland 680 engines. Leyland knew what would be expected of a rail application, or so the company thought, while British Rail was looking to outsource new rolling stock production.
Experiments started using nothing more than a Leyland National body slung on to the top of a rail underframe for proving purposes.
More testing times
The first prototype became known as LEV1 (Leyland Experimental Vehicle) and was even powered by the National’s Leyland 500 series diesel coupled up to a semi automatic gearbox and was assembled at the Cumbrian Leyland bus plant in Workington. Differing to the National mechanically, LEV1 featured a freewheeling facility on the transmission to reduce fuel consumption and enable coasting on long flat sections of track similar in practice to existing mechanical transmission on other rail stock of this type.
The riveted construction, windows, seats and even the air operated doors were carried over straight from the National bus. Costs were kept low by the fitting of single axle bogies at either end of a modified freight wagon frame, so the number of wheel sets, axles, springs and brakes were halved over the traditional DMU.
After some testing in the UK, and also in the USA, it became apparent that a two-car unit would be required, still heavily reliant on bus components but rail guidelines dictated a reinforced cab area and some extra internal body strengthening. The flawed 500 series engine proved, as it did in almost every other application, to be not fit for the job. The legendary 680 series engine had by now been replaced by the Leyland TL11 turbo diesel, so this engine rated at 200bhp per unit became the choice of power once again, coupled to a freewheeling version of the Leyland Hydra-Cyclic gearbox. The first running prototype became the class 140 which entered trails on various parts of the regional network in 1980 with a mixed reception from drivers and passengers.
Out with the old
Replacing the first generation DMUs would prove to be a tough task, regardless of how old some of them were (1950s). They were still the perfect solution for branch line running. They were cheap to run and of excellent quality, especially the Class 101 produced by MCW, and had useful features including plenty of doors and more than ample cycle space for those summer tourists. The simple Class 140 was nothing more than a glorified National bus bodied low cost alternative which was cramped, noisy, offensively uncomfortable at speed and downright ugly. But it was very cheap to produce, and was this factor alone which spurred the Government to be so keen to invest in this new rolling stock programme.
After modifications to the cab area, full scale production of 20 units started on what became known as the Class 141. All bodywork was constructed by Leyland Bus which was then transported to British Rail Engineering LTD (BREL) in Derby where the chassis and running gear were fitted. Once again, the drive ine was 2x Leyland TL11 horizontal diesel engines rated at 200bhp with Leyland Hydra-Cyclic gearbox and cardan shaft transmission with freewheeling function.
Although this new class looked superior to the prototype 140, the ride comfort, a consequence of a long wheelbase the axles being fitted directly to the frame, still caused many complaints from passengers, and tight curves in the track would cause noise & severe wear on the wheel flanges.
The same old story
Some major issues with regards to reliability to the drive line dogged the train’s reputation. Also, the rate of failure of both the engine and gearbox started to cause great concern to BR management. The main cycle of the engine in rail application involves constant bursts of maximum power followed by lengthy periods of idling. This causes a huge thermal shock as the engine heats up then cools down time after time, at the end of the line; the engine can then be subjected to extended periods of tickover. Carbon and soot rapidly build up within the combustion chamber at a far faster rate than in road use. Eventually, will cause hot spots within the engine, thus damaging or – at worst – melting the pistons, burning out the valves and contaminating the oil.
The gearbox was simply not man enough for the job either. The clutches or brake bands within the transmission were notorious for burning out rapidly, especially when driven hard. In cases where maintenance standards were not exacting, the oil filters in the gearbox would clog up resulting in oil starvation and eventual seizure of the transmission. The braking system was open to discussion also, the brake blocks acted directly on the wheel flanges but were actuated by cable rather than the traditional direct system using air chambers.
This meant that unless strict adjustment was regularly carried out, the brakes could potentially and quickly become ineffective, and later classes of train went back to a direct acting brake system or had it retro fitted.
Problems for Leyland really hit home after it supplied 95 sets of new Class 142 units, which commenced production in 1985. Many of these new trains now ran in severe conditions and the failure rates soared out of control. In the ideal world, the engineering alliance of BR & BL would have been quickly scrapped, but this was vital business for Leyland at a time when the bus an coach market was dying, and British Rail was under extreme pressure to modernise while also being tied to contract with Leyland.
Matters came to a head in the late 1980’s whereby BR, frustrated and tired of persistant breakdowns and running problems with the driveline, forced Leyland into a corner and threatened them with legal action over lost revenue. By now Leyland had passed from State ownership to Management buy out and into the hands of the Volvo Corporation.
Leyland hits the buffers
Even though Volvo initially ran Leyland Bus as a standalone business, the enormous cost of rectification which included the fitting of Cummins L10 engines and Voith dual stage gearboxes, would have no doubt sent Leyland into bankruptcy. Volvo therefore, and with huge reluctance, footed the massive bill. Following this fiasco, Leyland sold the design patents to the Hydra-Cyclic gearbox and rail powertrains to Cummins.
Many future classes of DMU on the BR network would feature the ultra reliable Cummins/Voith powertrain combination. The Class 142 eventually settled down to be a reliable and trusted set, even if they are still loathed by the passengers who rely upon them. The current Voyager fleet operated by Virgin Trains and Cross Country Trains feature Cummins power systems, specially developed for rail applications.