Original sentence: A revolutionary change took place when the Midland built a small fleet of 2-8-0 tender engines to handle the heaviest freight trains -- the unique S&DJR 7F 2-8-0 series -- with Walschaerts valve gear and the greatest tractive effort ever delivered by a Derby locomotive.The LMS 4F 0-6-0 tender locomotives worked some trains down from Bath -- they were commonplace on the Bath to Bristol services -- and the Western Region drafted in green liveried standard class 5 4-6-0s in the 73XXX series, with class 4 75XXX locomotives working from the Bournemouth end.The line was completed remarkably swiftly, notwithstanding financial difficulties which involved the contractor discontinuing work for a period, and on 20 July 1874 the Bath Extension -- almost immediately thought of as the main line, was opened
Edited sentence: A revolutionary change took place when the Midland built a small fleet of 2-8-0 tender engines to handle the heaviest freight trains—the unique S&DJR 7F 2-8-0 series—with Walschaerts valve gear and the greatest tractive effort ever delivered by a Derby locomotive.The LMS 4F 0-6-0 tender locomotives worked some trains down from Bath—they were commonplace on the Bath to Bristol services—and the Western Region drafted in green liveried standard class 5 4-6-0s in the 73XXX series, with class 4 75XXX locomotives working from the Bournemouth end.The line was completed remarkably swiftly, notwithstanding financial difficulties which involved the contractor discontinuing work for a period, and on 20 July 1874 the Bath Extension—almost immediately thought of as the main line, was opened