Abstract: The effects of setting pressure and motored speed on the movement characteristics are studied and the reaction deviation is analyzed using direct-acting relief valve, which is low cost and has simple structure to realize intake valve closing and continuously variable valve lift hydraulic valve train. Results show that the maximum valve lift increases with the setting pressure under the same engine speed. The difference of opening degree under different setting pressure is small and it gradually delays as the engine speed increases. Under the same setting pressure, the maximum valve lift increases with the engine speed, and at setting pressure of 4.5 MPa the increase trend slows down. The contribution of the mechanism inertia to the lift improvement is negligible. The Chi-square tests show that the related parameters follow normal distribution and the values of the parameters are estimated mean value and the deviation is the mean square error. The valve action has good consistency. With the increase in the hydraulic oil temperature, the maximum lift decreases, and the closing time gradually advances.

Key words: power machinery and engineering, variable hydraulic valve train, early intake valve closing, motored speed, set pressure, deviation analysis