Abstract: The deflection of an axle when under load is monitored by at least one load monitoring device mounted on the axle. At least one pair of strain gauge elements forms each load monitoring device, the strain gauge elements of each pair being arranged to measure strain in different directions. An amplifier is connected to the load monitoring device and adapted to emit a signal depending upon the load. A comparator circuit is connected to the amplifier, the comparator circuit being arranged to activate an alarm should the signal received from the amplifier exceed a predetermined value. Preferably the comparator circuit is adapted to both emit a continuous signal when the system is energized and the load on the axle is smaller than a predetermined weight, and to change the signal to another signal when the load exceeds the predetermined weight, the signal being used to control the alarm.