[a] This central workshop was set up in 1897 by South Indian Railways at Nagapattinam to maintain steam locomotives.

South Indian Railways decided to move the workshop to Trichinopoly (present-day Tiruchirappalli) because of its better location.

The workshop primarily maintains coaches and diesel and heritage steam locomotives and manufactures wagons.

In addition to locomotive overhaul, the diesel shop has the following support shops: GOC performs the following carriage maintenance: The workshop also manufactures and converts Nilgiri Mountain Railway coaches and exports old MG coaches after maintenance and remodeling by RITES.

It supplies wheels for rolling-stock maintenance and manufactures steam locomotives for the Nilgiri Mountain and Darjeeling Himalayan Railways.

The wing includes a tool room and foundry, diesel component, machine, wheel, fabrication and smithy, erecting and mechanical millwright shops.

In August 2021, an X-class coal-fired steam locomotive manufactured for the Nilgiri Mountain Railway (NMR) was dispatched by road to Mettupalayam for trials prior to operational deployment.

GOC's safety department, in existence for 30 years, uses training, drills, shop-floor counseling, data updating and the scientific elimination of work-related hazards.

GOC has a Chemical and Metallurgical laboratory where quality analysis of materials procured by the stores are undergone.

It has till now indigenously manufactured 6 X-Class Steam Engines, 4 from 2011-2014 and 2 from 2021-2022, for the use on the Rack-Adhesion route between Mettupalayam and Coonoor in the Nilgiri Mountain Railway.