Hydraulic System Failure Analysis

When a hydraulic system fails, the first consideration should be the合理性 of its design. The fundamental performance of a hydraulic system, including hydrostatis components, depends largely on sound design principles. This is particularly evident when analyzing failures in imported equipment, often due to differences in manufacturing organization.

Foreign manufacturers typically employ collaborative approaches, while domestic practices often lack systematic communication between hydraulic designers and original equipment manufacturers. This disconnect can result in hydraulic systems, including critical hydrostatis elements, that are poorly suited to their intended applications.

A prime example comes from troubleshooting the hydraulic system of a vertical mill—a core piece of equipment in a cement production line imported from Germany. The hydrostatis components of this system operated primarily in a pressure-holding state due to minimal roller displacement. For efficient operation, the hydraulic pump needed to unload during pressure holding to reduce heat generation, maintaining proper oil viscosity and ensuring production capacity.

Unfortunately, the imported system used a common overflow valve loading method that prevented proper unloading—a clear case of design不合理 affecting hydrostatis performance. This illustrates that hydraulic system design must not only ensure proper functionality but also consider operational efficiency and component protection.

When designing hydraulic systems, engineers must consider not only whether the hydraulic circuit can fulfill the machine's operational requirements but also pay attention to component layout—particularly the positioning of elements in manifold valve designs involving hydrostatis components. For example, in circuits comprising three-position directional valves, pilot-operated check valves, and one-way throttle valves, the pilot-operated check valve must connect directly to the directional valve, which should utilize a "Y" type neutral function.

In circuits using electro-hydraulic directional valves with "M" type neutral functions, either external control or internal control with pre-pressure check valves must be employed to ensure proper valve operation. These design considerations are crucial for maintaining the integrity of hydrostatis systems under varying operating conditions.

Additional design factors include the合理性 of the oil tank design and the layout of hydraulic lines. In harsh environments, special attention must be paid to protecting exposed hydraulic components. For instance, hydraulic cylinder rods used in metallurgical applications are often exposed to atmospheric contaminants.

These rods undergo reciprocating motion while exposed to abrasive wear, corrosive gases, and potential contamination ingress through gaps between the rod and guide sleeve. Contaminated oil then accelerates wear of cylinder components. A simple yet effective design solution is adding protective sleeves to piston rods, significantly reducing these hazards in both standard and hydrostatis systems.

Some designers, seeking simplicity, specify "green vertical纹 paint for internal and external tank surfaces" in technical requirements. This often leads manufacturers to skip acid phosphating treatment of internal surfaces. Over time, paint deterioration can contaminate the oil, clogging suction filters and causing pump cavitation or pressure issues—problems that are particularly detrimental to sensitive hydrostatis components.

Generally, hydraulic equipment assembled and tested by reputable manufacturers meets acceptable technical standards. However, problems often arise during maintenance when inferior replacement components are installed, inadvertently introducing failures into otherwise sound systems—including critical hydrostatis elements.

For example, a paper mill replaced the cartridge in a dual-cartridge precision filter of their hydraulic system. Within six days, the system failed due to clogging. Inspection revealed the new filter cartridge had significant manufacturing defects—regularly distributed micropores and cracks that rendered it ineffective. Poor quality filter paper containing embedded contaminants made the new component itself a source of system pollution rather than protection, particularly harmful to sensitive hydrostatis components.

Some hydraulic power unit manufacturers neglect proper system flushing during final assembly, mistakenly relying on component cleaning alone. This leaves contaminants introduced during assembly in the system, creating potential failure points in hydrostatis and other critical components.

Equally problematic is assembly performed concurrently with welding operations, which can introduce weld spatter and debris into hydraulic systems. Proper cleaning requires circulating fluid at specific pressures and velocities through each circuit individually. Pre-assembly component cleaning is insufficient and cannot replace post-assembly system flushing—especially important for maintaining the precision tolerances of hydrostatis components.

Leading hydraulic power unit manufacturers now recognize post-assembly flushing as a critical quality assurance measure. Additionally, thorough deburring of hydraulic manifold blocks represents another essential manufacturing step often overlooked. All manufacturing processes must adhere strictly to specifications, with rigorous cleaning to achieve the required oil cleanliness standards before system commissioning—particularly important for hydrostatis systems where even minor contamination can cause significant performance issues.