There's the rattling, the shuddering, the bouncing and the occasional squealing. You don't have to be a trainspotter to know you're riding a Pacer.British Rail and the successor Passenger Rail operators tended to exile them from London, although they could be relegated to the Midlands and the North.
Essentially, each one is an old Leyland Motors bus frame mounted on train wheels and, thanks to the vehicle's rudimentary suspension, regular travellers are all too familiar with the distinctive sounds and sensations.
Pacer from the 143 series, Manchester Piccadilly, 10 March 1997.
The cars' rough riding properties contributed to the nickname, "nodding donkeys," which reflected their design, and the rattling and bouncing could only be augmented by the opposed joints in British track.
Pacer carriages aren't fitted with bogies. This means they have just four wheels instead of the usual eight. The lack of bogies also means there's only one layer of suspension springs, rather than two, which "can make the ride rather bouncy", says Simon Iwnicki, director of the Institute of Railway Research at Huddersfield University. "There aren't many vehicles that are as long as the Pacer that have just four wheels."The long wheelbase -- it is a bus body, after all -- is evident in this picture.
This set-up also means the Pacer can emit a distinctive - and to many passengers, annoying - squealing noise as it runs through curves. It also limits the top speed to 75mph.
Pacer set at Manchester Victoria, 22 May 1995.
The Pacer, arguably, lasted as long as it did, because nobody attempted to pretend that it was anything other than a budget-priced rail car using bus components. And 3 and 2 seats that would look right on a yellow school bus (which, in DeKalb, are now operated by First Student, another division of First Group.)
Budgets were tight and British Rail was under great pressure to cut branch lines, says [author Christian] Wolmar. Meanwhile, at its factory in Workington, Cumbria, motor manufacturer British Leyland had produced a single-decker bus, the National, which needed to sell in high volumes to be viable.That's more honest than putting an intercity bus body on two axles and pretending it's an intercity flyer.
"We had one practical chap [who] suggested maybe you could take the body bit of the Leyland National and put it on a rail track," says Eric Woodcock, who was a bus designer at the state-run conglomerate at the time and now campaigns on public transport issues.
Simultaneously, British Rail had been working on freight wagon technology, and engineers from both nationalised companies began collaborating on a way to fuse the National's body with a bogie-less chassis to create a cut-price diesel multiple unit (DMU) train.
Aerotrain coach at Green Bay, Wisconsin.
In an ideal world, you do not want to make a train that looks like a bus. Or a string of buses.
The article notes that Pacer enthusiasts seek to preserve some of the railcars. They'll be easier to keep in service than the short Aerotrain consists left in our museums.