Hydraulic Components & Systems Inspections | SPI Borescopes

What is a Hydraulic System?

A hydraulic system is typically comprised of a pump, a cooling unit, reservoir, hoses or lines, a motor, valves, filters, and the hydraulic fluid. Most pumps move some type of fluid. Not all of them move oil. For instance, hydraulic power plants pull from a reservoir to move water through a turbine—not oil.

It works by applying force at one point, which is transferred as energy through the oil. After hydraulic fluid enters the pump from the reservoir, the pump pulls energy from the engine in order to transport the fluid, thus creating hydraulic pressure and flow.

The valves of any hydraulic system are extremely important for the movement of the highly pressurized fluid. Valves restrict and redirect the fluid throughout the mechanical system. The system speed depends entirely on the force exerted as the liquid flows. As the machine operates faster and continuously, the cooling unit manages the temperature level.

Why is it Important?

First of all, administering frequent hydraulic components and systems inspections allows you to identify and locate avoidable problems before they become a much larger catastrophe. These preventative maintenance checks protect against erosion, corrosion, and rust. The fluid can continue to properly cool, transmit power, and contain contaminants. If you suddenly have a leaky valve, catching it before it causes any damage is critical.

Hydraulic Components and Systems Inspections List

Since not every hydraulic system is exactly alike, this list will provide you with some common areas to thoroughly examine when you conduct your inspection. It’s crucial to prepare the scope of your inspection beforehand so that you know what to expect as you walk through the inspection stages.


For a hydraulic power plant inspection, the technician must carefully inspect the shaft interior that houses the water wheel blades, bearings, and deposition material. These shaft types require long remote visual inspections (RVI) tools to inspect down into the shaft. Articulating borescopes with 4-way, 360-degree articulation are highly accurate and capture sharp, useful images inside these deep shafts.


While it is not uncommon for some contaminants to enter the system, if you keep most of them out then it avoids regular issues. Some things to look for include sediment and variation in fluid color. You should also check the odor of the fluid. Remember, unless the fluid is tested, a visual inspection will only provide you with symptoms of excessive contamination.

It is considered standard procedure to obtain a fluid sample and send it to the lab for testing. A laboratory analysis is important to the hydraulic components and systems inspections process. This will ensure the equipment continues to function optimally.

Reservoir & Fluid Levels

This inspection should be frequent because of its importance to the operation of the machine. If hydraulic fluid is necessary for the equipment to function then check the fluid levels. Clean the fill area and pre-filter the oil before filling. Never poke holes in the screen to make the process move faster. This can cause contaminants to enter the system.

Make certain to use the exact viscosity grade and oil brand found within the reservoir. Never mix the oils because these come in a variety of types. It could cause problems with the machine if the incorrect oil were poured into the reservoir.

Inspect the fill screens, breather caps, and breather filters, along with the reservoir itself and site glass (if one is present). You should look for signs of aeration (bubbles) and foaming, along with variations in odor and color. If the pump is taking in air, you may hear a gargling noise. If any of these items show signs of wear or damage, replace them immediately.

Piping Systems

Leakage is a regular problem in industrial hydraulic systems. It has dangerous ramifications for the environment as well as being a safety hazard that can lead to overheating and sluggish operation. It also lets contaminants into the system while reducing power.

Regular inspections can prevent these issues. Piping systems need to be checked internally and externally. Look for bubbling, frays, leaks, or any other signs of wear. Carefully inspect the seals, fittings, couplings, and valves of the pipes, hoses, and pipe connections.

Mechanical Inspection

A visual inspection of motors, pumps, cylinder rods, and other internal hydraulic components is necessary to identify any abnormalities. A video borescope is ideal for internal inspections since they can provide a clear and detailed view. Some signs to look for include dents, or other types of damage. Don’t forget to listen for any unusual sounds, such as a high-pitched whine or other noises that could indicate cavitation or oil starvation.

Safety First

Maintaining a hydraulic system is as much about the operation of the machinery as it is about the safety of the workers. Prior to beginning, always put on protective gloves and safety glasses, along with any other appropriate safety wear. Use dependable diagnostic equipment, such as borescopes and pressure gauges, to conduct your inspection.

These systems must be adequately inspected and worked on to avoid dangerous situations. This ranges from checking relief valves and safety railings to checking high-pressure hose fittings and making certain to bleed the system before working on a pressurized area.

Checking the temperature is one of the most important safety inspections a technician will do. A typical temperature range is between 110-140F (45-60C). You can easily use an infrared thermometer (usually a scanner) to check the temperatures of the servo valves, motors, and other areas. Check for hot spots and rotor bearing temperatures.

While the actual temperature at which damage occurs varies; temperatures over 150F (65C) could indicate a sticking relief valve or problems with the cooling unit. Before working on any machinery, wait for the temperature to decrease to a safe range.

Articulating Borescopes

When engineers need to reach places invisible to the naked eye, such as an oil piping system, they turn to articulating borescopes. Video borescopes capture high-quality images and video that can be stored for a closer examination. These valuable optical gadgets can fit through tiny openings to deliver the results of a careful inspection. Examine the hydraulic valve body, diesel injector body, hydraulic sleeve, and much more with these RVI tools.

Advanced Articulating Borescopes

Hydraulic systems are used across multiple industries, such as the automotive, entertainment, and aerospace industries. Articulating borescopes are ideal tools for hydraulic components and systems inspections.

Borescopes are highly flexible and used across a wide variety of applications such as looking at the inside of hydraulic brakes, motors, construction hydraulic equipment, hydraulic platforms, and other hydraulic systems. Technicians can obtain a high-definition visual inspection of these extremely hard-to-reach areas. By conducting regular preventative maintenance, you ensure your hydraulic system continues to operate efficiently

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