Ralph, previously Ralph Sadler, after the Snowdon Mountain Railway's consulting engineer, from 1964 to 1977, and Aylwin from 1977 until October 1978, is an engine on the Snowdon Mountain Railway. Ralph was manufactured by the Swiss Locomotive and Machine Works at Wintherthur, Switzerland in 1923.
- Built- 1923
- Designer- Winterthur
- Builder- Winterthur
- Arrived on Snowdon Mountain Railway- 1923
- Original Railway- Snowdon Mountain Railway