In recent years, more and more devices, such as smart mobile devices, smart tags, sensors, or chips have been connected to the Internet. All these devices are part of the Internet of Things, a technology that has experienced rapid development, along with technologies such as cloud computing or big data. In this paper we propose a system for monitoring fuel consumption for a fleet of locomotives, using Raspberry Pi devices to which sensors are connected, in the context of the Internet of Things. We also emphasize the authentication of Raspberry Pi devices inside the system and present how data consumption data are transmitted between the components of the system.