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The WOODWARD 9905-657 is a specific model of TM-25LP Linear Actuator.
WOODWARD 9905-657: TM-25LP Linear Actuator
The WOODWARD 9905-657 is a precision actuator designed to provide accurate mechanical positioning in response to control signals. It’s primarily used in industrial applications to regulate prime movers like engines and turbines.
Product Overview
This part number designates a particular configuration within Woodward’s robust TM (Turbine/Engine Master) series of actuators, specifically the TM-25LP variant.
- Product Type: Linear Actuator
- Manufacturer: Woodward
- Part Number: 9905-657
- Model Designation: TM-25LP
- Key Features:
- LP (Low Pressure): This signifies that it operates with a lower hydraulic or pneumatic supply pressure compared to high-pressure versions. This makes it suitable for systems where high-pressure fluid isn’t readily available or desirable.
- Dual Coil: This indicates the actuator utilizes two coils for its operation, which can offer advantages like redundancy, improved control characteristics, or specific control strategies.
- “Retracts w/ LVDT”: This is a crucial distinguishing feature for this part number. It means the actuator’s shaft retracts as its default or desired movement on increasing signal (or when commanded), and it includes an integrated Linear Variable Differential Transformer (LVDT). The LVDT provides precise electrical feedback on the exact position of the actuator’s shaft, enabling closed-loop position control by an electronic governor or control system.
- Function: Converts a control signal (typically a hydraulic or pneumatic pressure signal, or an electrical signal to an internal solenoid) into precise linear force and displacement. This mechanical output is then used to operate fuel racks, valve linkages, or other control surfaces on prime movers or industrial machinery.
Detailed Product Description
The Woodward TM-25LP Actuator is engineered for reliable and precise performance in demanding industrial environments. The TM series is well-regarded for its durability and adaptability across various power generation and industrial control applications.
- Hydraulic or Pneumatic Operation: TM actuators can operate using either hydraulic fluid or pneumatic pressure as the working medium, depending on the specific model and system design. The “LP” designation highlights its suitability for lower supply pressures.
- Precision and Repeatability: These actuators are designed to provide highly accurate and repeatable positioning. This precision is vital for maintaining stable speed, load, or other critical parameters for engines and turbines.
- Robust Construction: Built to withstand harsh industrial conditions, including significant vibrations, wide temperature fluctuations, and continuous duty cycles. Woodward actuators are known for their robust design and long service life.
- Linear Motion Output: The actuator provides a linear force and stroke, meaning its output shaft moves in a straight line, directly connecting to and operating control linkages.
- Integrated LVDT Feedback: The inclusion of an LVDT is a significant advantage. It provides continuous, highly accurate, and reliable feedback on the actual position of the actuator’s output shaft to the electronic control system. This enables advanced closed-loop position control, allowing the governor to precisely track a desired valve or fuel rack position, which is critical for dynamic and stable control. This contrasts with other TM-25LP variants that might require external feedback (e.g., 9905-658, which “Extends w/o Feedback”).
Technical Specifications (General for TM-25LP Actuators, specific details for 9905-657)
| Parameter | Value |
| Product Type | Linear Actuator |
| Manufacturer | Woodward |
| Part Number | 9905-657 |
| Model Series | TM-25LP |
| Coil Type | Dual Coil |
| Fail-Safe/Direction | Retracts (on increasing signal/power) |
| Feedback | With LVDT Feedback (integrated position sensor) |
| Pressure Type | Low Pressure (LP) operation |
| Motion Output | Linear mechanical motion (1 inch / 25 mm max stroke) |
| Work Capacity | Typically 34 J (25 ft-lb) at 1034 kPa (150 psig) |
| Output Force | Typically 1334 N (300 lb) maximum at 1034 kPa (150 psig) |
| Response Time | Typically 0.065 seconds (25% to 75% step) at 1724 kPa (250 psi) |
| Typical Use | Engine speed control, turbine valve actuation, fuel rack positioning |
| Documentation Ref. | Woodward Industrial Turbine Products Catalog (Publication 25182), TM-25LP and TM-200LP Actuator Manual (Manual 82450) |
Typical Applications
The WOODWARD 9905-657 TM-25LP Linear Actuator is commonly found in a variety of industrial applications that require reliable, precise, and closed-loop mechanical control:
- Diesel and Gas Engines: For accurate and responsive control of fuel injection systems or throttle bodies, maintaining desired engine speed and load with high precision. The “LP” feature is useful where lower pressure hydraulic systems are available.
- Small to Medium Steam Turbines: For actuating steam admission valves, regulating steam flow to control turbine speed and power output, benefiting from the integrated LVDT for accurate valve positioning.
- Compressors and Pumps: Used in systems where precise flow or pressure regulation is achieved by adjusting heavy-duty valves or dampers.
- Industrial Machinery: In processes where direct mechanical control from an electronic governor is needed, and accurate position feedback is critical for system performance and stability.
