The S sets were a class of electric multiple units that operated on Sydney's suburban rail network from 1972 up until 2019. Originally entering service under the Public Transport Commission, the sets also operated under the State Rail Authority, CityRail and Sydney Trains. Prior to their retirement, the S sets were the last class in the Sydney Trains fleet to not be air-conditioned, earning them the nicknames "Tin cans" and "Sweat Sets". They were also nicknamed "Ridgys" because of their fluted ("ridged") stainless steel panelling; they shared this nickname with similar looking K sets and C sets. The final sets were withdrawn from service in June 2019. Delivery Two manufacturers built 509 carriages, based on a largely common design: 359 carriages were built by Comeng between 1972 & 1980. They were externally distinguished by the peaked front of driving cars and a prominent line across each side of its carriages above the upper deck windows. They also had thin flutings at the top and upper half of the sides of the carriages. The Series 1 Comeng power cars featured no fluting on the lower half of the carriage and one peaked front and rear end. The Series 2/3 Comeng power cars featured fluting on the lower half of the carriage and one peaked front end. These two types were identical aesthetically. The Series 4 Comeng power cars were identical to the Series 2/3 cars with headlights fitted above the destination box. Cars D4011–D4020 featured the driver/guard window and vertical window close together with no pantograph. These carriages also lacked a driver/guard doors and had no destination boxes. Cars D4021-D4095 featured the same as a Comeng power car with a driver/guard door with no pantograph. These cars had no destination boxes. All 85 driving trailers were converted into trailer cars with the driving compartment, cab and guard instruments removed with head and tail lights plated over. 150 carriages built by A Goninan & Co between 1978 & 1980. They were externally distinguished by the flat front of driving cars and lower windows on the upper deck. They also had larger windows at the end between carriages. They also had thicker flutings at the top and around the top of the carriages and lacked the line around the top of the sides of the carriages unlike the Comeng carriages. History In service Following the successful trial of four double-deck power cars built