In operating load of tractor power take-off (PTO), no damage or small damage load occupies a large proportion to cause long test time and poor economy in durability tests. Eliminating these loads can obtain the acceleration load spectrum. Here, taking a 40 HP tractor as the study object, Daubechies wavelet was used to decompose the measured load signal of the tractor PTO, reconstruct high frequency wavelet coefficients and get high frequency wavelet components. On the premise of the total pseudo damage remaining basically the same, the appropriate threshold was selected and combined with the envelope damage identification method, load segments with larger damage were extracted from the original load signal and spliced into the acceleration load spectrum. Acceleration load spectra with compression ratios of 42.0%, 49.8%, 61.7%, 62.4% and 81.9% were obtained, respectively. Based on theories of frequency domain, amplitude domain, statistical parameters and fatigue damage, the correctness of the obtained acceleration load spectrum and its similarity to the original load spectrum were verified. The results showed that frequency domain and amplitude domain distribution curves of the acceleration load spectrum and the original load spectrum are similar on the premise of the pseudo damage being basically the same; errors of its maximum value, root mean square value, kurtosis coefficient and other parameters all are less than 5%; the damage effect of components is basically the same; the proposed load acceleration editing method is suitable for making acceleration load spectrum of tractor components, and can provide a reference for making acceleration load spectrum in agricultural machinery field.
Key words
wavelet transform （WT） /
tractor PTO (power take-off) /
envelope /
load acceleration
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