What is the main purpose of the power transfer unit (PTU) in a hydraulic system?

• A. To cool the hydraulic fluid
• B. To supply additional hydraulic fluid volume
• C. To filter contaminants from the fluid
• D. To operate the engine-driven pumps

Answer: (B)

The main purpose of the power transfer unit (PTU) in a hydraulic system is to supply additional hydraulic fluid volume. This component is designed to manage and enhance hydraulic pressure and flow within the system, especially during times when increased hydraulic demand occurs, such as during takeoff or landing in an aircraft. By providing extra hydraulic fluid capacity, the PTU ensures that the hydraulic system operates efficiently, maintaining adequate pressure and volume to power various hydraulic actuators and mechanisms.

The role of the PTU is crucial in maintaining system reliability and performance, particularly under varying operational conditions. This ability to augment fluid volume helps in maintaining consistent hydraulic performance even when other components may be experiencing limitations.

Other functions, while important in a hydraulic system, are distinct from the primary purpose of the PTU. Cooling the hydraulic fluid, filtering contaminants, and operating engine-driven pumps are separate processes that might involve different components or systems designed specifically for those roles. Thus, the PTU's ability to increase hydraulic fluid availability directly supports the overall effectiveness of the hydraulic system.