Vibration acceleration is the most direct phenomenon caused by the dynamic load of the system. At the same time, the measurement of vibration acceleration is very difficult, which is a very common measurement parameter in practical engineering. As shown in the figure, the vibration acceleration components and their spectrum of different interface nodes on the rocker arm box are given. The spectrum components of BP1 are mainly the meshing frequency and its multiple frequency of each gear pair. Besides the meshing frequency and its multiple frequency, the spectrum components of bp17 also have the lower order frequencies (13, 17.25, 27.5, 29 Hz) corresponding to the box vibration mode, as shown in figures (E) and (f). This is because BP1 is close to the root of the rocker arm, the global deformation of the rocker arm box is small, while bp17 is located at the free end of the rocker arm, the global deformation of the rocker arm box is large.
Therefore, to measure the deformation frequency of the rocker box, the measuring point should be selected near the free end of the rocker; and the deformation frequency of the rocker box picked up in the Y and Z directions of bp17 point is not the same, which is related to the specific vibration mode of the rocker box.