The Role of Tamping Machines in Railway Construction and Maintenance
Tamping machines are core large-scale equipment for railway track maintenance, primarily used on ballasted tracks. They compact loose ballast under sleepers, precisely adjust track height, level and alignment, eliminate issues like empty sleepers, enhance ballast stability, and ensure safe and smooth train operation. Suitable for new line construction, existing line overhaul and routine maintenance, their operating accuracy directly affects track smoothness.
Application of Our Servo Valves in Railway Tamping Machines
We have established long-term cooperation with railway tamping machine manufacturers in many countries, with an annual shipment volume of several hundred units for these servo valves.
The RT6225M Series, RT6615E Series, RT6617E Series and RT6215M Series produced by our company can fully replace MOOG’s 0062 Series, D661 Series, D662 Series and G631 Series.
Subsystems Using Servo Valves in Tamping Machine and Their Functions
As the “heart” of the tamping car’s electro-hydraulic control system, servo valves run through multiple core operation subsystems, and the accurate operation of each system relies on the regulation of electro-hydraulic servo valves, as follows:
1) Lifting and Lining Servo System:
Its core function is to correct track height (lifting) and alignment (lining) deviations. A measuring trolley detects discrepancies between actual and designed track positions, converts these deviations into electrical signals, and transmits them to servo valves. These valves precisely regulate hydraulic fluid flow and direction to drive lifting and lining cylinders, achieving millimeter-level track positioning. This is a critical subsystem for ensuring smooth railway operations.
2) Tamping Device Servo System
It controls the lifting, clamping and vibration of tamping picks. Upon receiving control signals, the servo valve regulates hydraulic power to precisely control the tamping depth with an error ≤ 1mm. It dynamically adjusts clamping force based on ballast resistance for asynchronous stable clamping, ensuring uniform ballast compaction under sleepers and enhancing tamping quality and efficiency.
3) Tamping Device Servo System
It is used for tamping ballast at the shoulder of sleepers. The servo valve controls the lifting and vibration frequency of the tamping device, increases the lateral resistance of the ballast, further improves track stability and assists in consolidating the tamping effect. The synchronization and stability of its actions are accurately controlled by the servo valve.
Core Requirements of Each Subsystem for Servo Valves
Tamping Machine work in harsh environments (high-frequency vibration, high temperature, easy contamination of hydraulic oil) and have extremely high requirements for operation accuracy. Therefore, each subsystem has clear requirements for servo valves, focusing on three cores: precision, stability and durability:
- High-precision Control: Servo valves must have excellent linearity and low hysteresis, with control accuracy within 0.1%, and can accurately respond to 4-20mA current signals to ensure millimetric control of lifting, lining and tamping depth, avoiding excessive track deviation.
- Fast Response Speed: The response time of servo valves shall be ≤ 10ms, which can quickly feed back control signals, adapt to the continuous dynamic operation needs of Tamping Machine, avoid operation errors caused by action lag, and especially meet the real-time correction needs of lifting and lining.
- Strong Resistance to Harsh Working Conditions: It must have excellent vibration and pollution resistance, be able to adapt to high-frequency vibration of Tamping Machine (vibration resistance up to 30g), resist impurities in hydraulic oil to prevent nozzle blockage and valve core jamming, and adapt to the working temperature of -20℃ ~ 70℃ with small zero drift and reliable sealing.
- High Reliability: Servo valves must have long service life and low failure characteristics, be able to adapt to long-term continuous operation of Tamping Machine, reduce unplanned shutdowns, lower maintenance costs, and adapt to long-cycle railway maintenance needs.