high tractive effort. The reason for this modification was that the typical speed of a train ascending the bank was approximately that at which the transmission would change between first and second gear, and so it tended to "hunt" between the two. The repeated gear changes under full power caused excessive wear and damage, and the simplest way to avoid the problem was to lock first gear out of action, so the locomotives used only second gear and upwards. First-generation diesel multiple units were somewhat underpowered and climbed the bank often at little above walking pace, especially as they aged; it was not unknown for them to need to be rescued by a banker. The more powerful modern DMUs negotiate the line with little speed reduction, though there remain rules that at least half of the engines of a Class 220 or 221 must be working in order to ascend. Regular banking of passenger trains ceased in the summer of 1988 when the Bristol to Scotland sleeper was modified to have two portions from Poole and Plymouth joining at Birmingham. Many current freight trains still need to be banked however and since 2003 DB Cargo UK use dedicated Class 66 locomotives, nos. 66055-057 and 66059,(and formerly 66058). These are modified with air-released swing-away buckeye couplers and a downward facing light to assist nighttime buffering up. Operation in steam days In the early days banking was performed by a pilot engine attaching to the front of the train, with rear banking only in emergency. Reason included the use of dummy rather sprung buffers, the Norris Class A Extras have adaptations to increase the adhesive weight under load. At the top the banking pilot would slip away from the train engine which would slack off power and allow the pilot to draw ahead by 30 yards and be directed into a siding with the policeman then resetting the points for the train to continue on the main line. From May 1842 after the Norris engines were saddletanked they operated all trains up and down the Lickey themselves with train engines being detached and remaining either at the North or South end of the incline. Rear banking was adopted later. The bankers would stand in a siding on the up side to the south. The load of each train would be telegraphed from Cheltenham. If the driver decided he needed more bankers than