The Ford R-Series is a range of bus and coach chassis evolved from designs made by Ford's Thames commercial vehicle subsidiary until the mid-1960s. A number of components were shared with the D-series lorry, including the engine which was mounted vertically at the front of the vehicle, ahead of the front axle so as to provide a passenger entrance opposite the driver. The original R192 and longer R226 models later became the R1014 and R1114 variants (nominally 10 and 11 metres long respectively with 140 bhp engines) which with constant revision and upgrading had become R1015 and R1115 by the mid-1980s. In an attempt to lower the floor height of the vehicle, the turbocharged diesel engine was tilted over to one side around 1978.