Abstract: In the modal research of cab, it is found that the cab roof panel vibration must not be ignored. The results of modal test indicate that when the natural frequency is 15.67 Hz (at 7th order frequency of cab), the vibration mode of cab appears as obvious vertical vibration of cab roof panel. The natural frequency of cab roof panel is calculated by utilizing the thin plate theory and then compared with the modal test results. Two cab simulation models are built in Matlab/Simulink environment. In one model, the cab as a whole is studied；in another, the cab roof panel isolated as an independent component is studied. Then the two simulation models are computed respectively in a bid to analyze the effect of cab roof panel vibration on the vertical vibration of cab floor. The results indicate that the effect rate of acceleration rms of cab roof panel vibration on the cab floor comes to 9% while the effect rate of peak value is 2%～3%. Mechanics analysis on the vibration mode of 7th order is carried out. From the viewpoint of mechanics, qualitative analysis is carried out on the phenomena of swing, pitching and turning around the vertical direction of cab vibration mode.

Key words: Cab, Mode, Roof panel, Vibration