Methods for Achieving Long-Term Synchronous Operation of Hydraulic Cylinders

Hydraulic cylinders are commonly used actuators in hydraulic systems, converting hydraulic energy into mechanical energy to achieve linear reciprocating motion. Due to their simple structure, stable operation, and smooth motion without transmission gaps or reduction gears, they are widely applied in engineering machinery, automation systems, and industrial equipment.

In many practical scenarios, multiple hydraulic cylinders need to operate synchronously. Achieving long-term and stable synchronization is essential for ensuring the performance and precision of equipment. This article outlines common methods to achieve synchronized operation, as well as typical issues and maintenance strategies.

1. Synchronous Circuit Using Hydraulic Motors

One solution is to use identical hydraulic motors with high manufacturing precision to provide nearly equal flow to each cylinder. Since the motors share the same design and dimensions, the flow rate distributed to each cylinder is nearly equal, resulting in synchronized movement.

Pros: Simple structure, moderate cost
Cons: Synchronization depends on precise manufacturing and uniform load distribution; some error is inevitable due to physical tolerances.

2. Proportional Valve with Feedback for Closed-Loop Control

This approach uses proportional valves and displacement sensors to form a closed-loop control system. One cylinder acts as a reference, while the other cylinder follows its displacement signal. The controller adjusts the valve opening in real time to maintain synchronized motion.

Pros: High control accuracy, fast response, suitable for precision applications
Cons: Higher cost, requires careful system design and maintenance

3. Dual-Pump System with Hydraulic Servo Compensation

By using two pumps with equal flow rates to drive the cylinders separately and introducing a servo compensation system, this method detects positional deviation and corrects flow imbalance dynamically. Typically, a roller and steel tape mechanism is installed on a crossbeam to detect differences in cylinder displacement. The signal is amplified and fed back to a servo valve to adjust oil flow and restore synchronization.

Pros: Capable of real-time compensation, ideal for heavy-duty or long-stroke operations
Cons: Complex system setup, requires high precision in tuning

4. Common Synchronization Issues & Maintenance Tips

Problems such as cylinder crawling or slipping often result from:

• Bent or misaligned piston rods

• Poor assembly of internal components

• Excessive friction due to improper fits

• Contaminants (e.g., iron filings) causing surface damage

Solutions:

• Inspect and realign mechanical components

• Replace damaged seals and parts

• Ensure clean hydraulic oil and proper lubrication

• Adjust tolerances during assembly

5. Key Strategies for Long-Term Synchronization

To ensure consistent synchronization over time, consider the following best practices:

• Use high-precision components (cylinders, valves, pumps)

• Design control systems with feedback (closed-loop preferred)

• Perform regular maintenance and calibration

• Monitor position and pressure deviations for early detection