Improved piston detector

The utility model relates to the technical field of detection machines, in particular to an improved piston detection machine which comprises a support, a sliding rail, a sliding body, a material disc, a transmission assembly and a material changing assembly. The material changing assembly comprises a discharging trolley, a feeding trolley, a tray support, a discharging driving component and a feeding driving component, the discharging trolley is moved to the position in front of the material tray, the sliding body brings the material tray out of the support and places the material tray on the tray support of the discharging trolley, at the moment, the discharging trolley moves upwards to support the material tray, and material taking is completed; when materials in the material disc are grabbed, the sliding body at the bottom end can stretch out to the position below the empty material disc, the material disc is placed on the sliding body through the feeding trolley, the sliding body at the bottom end drives