1, check whether the hydraulic rod leaks oil;
2. Check whether the seal of the hydraulic rod is tight;
3. Check whether the hydraulic rod is aging;
4. Check whether the lifting platform is improperly operated, such as overload.
Extension: The work of hydraulic rod mainly depends on the oil pressure, the clearance between tappet and seat hole, the clearance between valve stem and tappet, and the check ball valve in tappet. When the hydraulic tappet starts to work, because there is no oil pressure in the cavity, the tappet plunger is at the bottom, the gap between the tappet and the valve is large, and the valve produces short-term abnormal sound. With the operation of the engine, under the action of oil pressure, the plunger cavity in the tappet is filled with oil, and the plunger moves downward, which increases the effective working length of the tappet and reduces the valve clearance. Because the force generated by the plunger in the tappet is too small to compress the valve spring, the tappet will not move when the clearance between the tappet and the valve is too small. At the same time, due to the function of the check ball valve in the tappet, the oil pressure in the plunger cavity of the tappet can not be discharged quickly, so that the plunger stays in its original position and maintains its original length to form rigidity, thus pushing the valve to open. When the engine is running, the valve clearance keeps a certain clearance.