The invention relates to a system (10) for a vehicle trailer (106), in particular to a semi-trailer (106) comprising, a function block (30) with a data input (33) for receiving gear change signals (34) of a vehicle (108), in particular a utility vehicle (108), which tows said vehicle trailer (106). The function block (30) comprises a controller (35) for generating a torque-increasing request signal (36) in accordance with a received signal of the gearchange signals (34) and a data output (37) for outputting the torque-increasing request signal (36) to an electric motor control device (14) of at least one electric drive (12) of the vehicle trailer (106). The invention further relates to a vehicle trailer (106) with a system (10) and to a method for operating such a system (10).