LNER Class A4
The Class A4 is a class of streamlined 4-6-2 steam locomotive designed by Nigel Gresley for the London and North Eastern Railway in 1935. Their streamlined design gave them high-speed capability as well as making them instantly recognisable, and one of the class, 4468 "Mallard", holds the world record as the fastest steam locomotive. Thirty-five of the class were built to haul express passenger trains on the East Coast Main Line route from London Kings Cross via York to Newcastle, and later via Newcastle to Edinburgh, Scotland. They remained in service on the East Coast Main Line until the early 1960s when they were replaced by Deltic diesel locomotives. Several A4s saw out their remaining days until 1966 in Scotland, particularly on the Aberdeen - Glasgow express trains, for which they were used to improve the timing from 3.5 to 3 hours.
Mumbai Rajdhani Express
The 12951/12952 Mumbai Rajdhani Express is the fastest train on the Mumbai - Delhi sector and the fastest Rajdhani train as well as the fastest train (Considering ARS and including halts) in India. Mumbai Rajdhani Express is the first Rajdhani to get Alstom-LHB Coaches in India. It used to run six days a week until September 2000 after which Railways decided to run it daily. In its early days, it used to cover the distance of 1385 kilometres in each direction in 19 hours and 5 minutes. However, after the electrification of the route, the speed of the train improved and as of 2018, it takes 15 hours and 35 minutes when operating as train number 12951 at an average speed of 89 km/h (including halts) while on its return journey as train number 12952 takes 15 hrs 50 mins at an average speed of 88  km/h (including halts) thus making it the fastest train on the Mumbai - Delhi sector. Before the introduction of the LHB coaches, the maximum speed that could be attained with the conventional rakes was 120 km/h.But after introduction of LHB rakes the highest speed that could possibly be attained is 160 km/h but is restrictred to 130 km/h due to Head-On-Generation Technology. After their introduction, the LHB coaches enhanced the speed of the Rajdhani to more than 120 km/h and even touching 130 km/h most of the time. The highest attained speed was 140 km/h between Asaoti and Mathura, but it was only on trial basis for one month . Recently Virar-Vadodara-Godhra Section top speed is enhanced from 120 km/h to 130 km/h. Hence, Mumbai Rajdhani's time reduced from 16 hours to 15 hr 35 minutes while it continues to be the fastest train in India (including halts) with average speed of 91 km/h.It is the first train (along with 12953/54 August Kranti Rajdhani Express as both have Rake Sharing) to be experimented with HOG (Head On Generation) which powers the train directly from locomotive instead of an EOG or generator van .