Reservoir is a tank which store the hydraulic oil for recirculation through the hydraulic system.
A hydraulic reservoir, also known as a hydraulic fluid reservoir or hydraulic oil reservoir, is a vital component in hydraulic systems. Hydraulic systems use pressurized fluid to transmit power and perform work in various applications, such as industrial machinery, construction equipment, and automotive brake systems.

Importance of reservoir

A) Storage of oil :- It is main oil container which has capacity in liters.

B) Cooling of oil :- It acts as a cooling device for dissipation of heat in the oil through large surface area of the tank.

C) Separation of oil :- The dirt, dust wear particles settled down in the reservoir.

D) Structural support :- It acts as a base for pump-motor assembly, relief valve etc.

Construction of Reservoir


It consists of

A) Oil level indicator :- It is the level indicator to show the quantity of oil available in the tank.

B) Check valve :- It is provided in the return pipe to prevent back flow.

C) Baffles :- They are provided to reduce foaming of oil.

D) Breather :- It is provided for air circulation in the tank.

E) Filter :- It remove dirt from the air passing through the breather.

F) Drain plug :- It is provided to drain out used oil.

G) Sampling tap :- It is provided to collect sample of for testing of viscosity, etc.

The reservoir capacity should be three times the flow rate of the pump.

Rectangular shape helps for better heat dissipation per unit volume.

Hydraulic reservoirs come in various sizes and designs, depending on the specific application and hydraulic system requirements. They can be integrated into the equipment as a part of the system or added externally. Proper maintenance and monitoring of the hydraulic reservoir are crucial to ensure the efficiency and longevity of the hydraulic system. This includes regularly checking fluid levels, maintaining the right fluid quality, and ensuring the reservoir remains free from contamination.

Advantages and Disadvantages of Hydraulic Reservoir

A hydraulic reservoir, also known as a hydraulic oil reservoir or hydraulic fluid reservoir, is a key component in hydraulic systems. It serves several important functions in hydraulic machinery. Here are the advantages and disadvantages of hydraulic reservoirs:


Hydraulic Fluid Storage: The primary function of a hydraulic reservoir is to store hydraulic fluid. This ensures that there is a constant supply of fluid available for the hydraulic system to function properly.

Heat Dissipation: Hydraulic systems generate heat due to the energy transfer and friction within the system. The reservoir acts as a heat sink, dissipating this heat and preventing the hydraulic fluid from overheating, which can lead to reduced performance and damage.

Air Separation: Reservoirs often have baffles or other design features that help separate air from the hydraulic fluid. This prevents air bubbles from entering the system, which can cause cavitation and reduce system efficiency.

Debris Separation: Hydraulic reservoirs typically have filters or screens that capture and remove debris and contaminants from the hydraulic fluid, ensuring that the fluid remains clean and free of particles that could damage system components.

Fluid Expansion: Hydraulic fluid can change volume with temperature fluctuations. The reservoir provides space for the fluid to expand or contract, preventing overpressurization or cavitation during these temperature changes.

Sight Level Indicators: Many reservoirs are equipped with sight level indicators or gauges, which allow operators to monitor the fluid level easily and take appropriate action if fluid levels are too low.

Easy Maintenance: Reservoirs are usually easily accessible, making maintenance tasks such as fluid replacement, cleaning, and filter replacement straightforward.


Size and Space Requirement: Hydraulic reservoirs can take up a significant amount of space, which may be a limitation in some applications where space is at a premium.

Weight: The reservoir itself, along with the fluid it contains, adds weight to the hydraulic system. In mobile applications like vehicles or aircraft, this added weight can be a disadvantage.

Initial Cost: The installation of a hydraulic reservoir adds to the initial cost of a hydraulic system. This cost includes the reservoir itself, mounting hardware, and associated components.

Maintenance Requirements: While maintenance is relatively easy, it’s still a necessity. Neglecting maintenance can lead to fluid contamination and reduced system performance.

Fluid Evaporation and Contamination: Over time, hydraulic fluid can evaporate through the vent, and the reservoir can become contaminated if not sealed properly. This can affect the system’s performance and efficiency.

Potential for Leaks: Hydraulic reservoirs can be a source of fluid leaks if not properly sealed, which can lead to fluid loss, environmental concerns, and safety hazards.

Application of Hydraulic Reservoir

Hydraulic Fluid Storage: The primary function of a hydraulic reservoir is to store hydraulic fluid (usually hydraulic oil or hydraulic fluid) for the system. The reservoir’s capacity is designed to hold an adequate volume of fluid to supply the hydraulic components with the required fluid during operation.

Thermal Management: Hydraulic systems generate heat during operation due to the friction and energy losses in the system. The reservoir acts as a heat sink, allowing the hydraulic fluid to dissipate heat. Some hydraulic reservoirs have cooling systems (heat exchangers) to further manage temperature and prevent overheating of the hydraulic fluid.

Air Separation: Air can enter the hydraulic fluid due to leaks or aeration during operation. The reservoir provides a location where air can separate from the hydraulic fluid, allowing it to escape through vents or be purged through dedicated systems.

Contaminant Settling: Hydraulic systems can accumulate contaminants over time, such as dirt, debris, and particles. The reservoir provides a settling zone where these contaminants can settle at the bottom, away from the hydraulic components. This helps maintain the cleanliness of the hydraulic fluid and extends the life of system components.

Hydraulic Fluid Level Monitoring: Many hydraulic reservoirs have sight gauges or sensors that allow operators to monitor the hydraulic fluid level. Maintaining the correct fluid level is crucial for the proper functioning of the hydraulic system.

Fluid Filtration: Some hydraulic reservoirs are equipped with filters that help remove contaminants from the hydraulic fluid, ensuring that clean fluid is supplied to the hydraulic components.

Breather and Ventilation: Hydraulic reservoirs typically have breather caps or vents that help maintain atmospheric pressure inside the reservoir, preventing the collapse of the reservoir due to fluid withdrawal. They also prevent the entry of airborne contaminants and moisture into the system.


What is a hydraulic reservoir?
Hydraulic reservoirs are storage tanks that contain liquids or gases used in hydraulic power applications.

What is the function of the hydraulic tank?
The reservoir plays many roles in a hydraulic system. The primary function of a reservoir is to keep the system’s hydraulic fluid in a convenient location for the pump inlet. In addition to system requirements, the reservoir also contains excess fluid needed when the hydraulic system is operating.

What are the types of hydraulic tank?
Tanks are of two general types: non-pressurized and pressurized. Propower manufactures non-pressurized hydraulic reservoirs and pressurized reservoirs that operate up to 5 psi. Most systems are typically designed for equipment operating at normal atmospheric pressure.

What is a hydraulic tank made of?
The typical reservoir is constructed of welded steel plate and is designed to store and cool the fluid supplied by the system. Elevated designs offer easier access to the tank for maintenance.

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By Aditya

Hi, I’m Aditya Sharma, a professional blogger from Gurgaon, India and I launched this blog called aadityacademy on July 2021. is a mechanical Project-oriented platform run by Aditya sharma and I got the motivation to start aadityacademy blog after seeing less technical education information available on google.

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