 The Class 21E has a single cab and a gangway along the centre of the locomotive.It is equipped with a wireless data transmission system which can send the locomotive operation status, fault data and energy consumption data via GSM and Wi-Fi to a trackside station for analysis.It is also equipped with an axle temperature alarm device, fire alarm system, closed-circuit television (CCTV) system, wheel flange lubricating device and, as personnel safety measure, high voltage protective interlocking devices.