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Expert Guide to Hydraulic Cylinders for Excavators: 5 Critical Failure Signs & Cost-Saving Tips

Oct 17, 2025

Abstract

This examination delves into the operational principles, core components, and critical maintenance considerations of hydraulic cylinders for excavators. It provides a foundational understanding of how these actuators convert hydraulic fluid pressure into mechanical force, enabling the powerful and precise movements essential for excavation tasks. The analysis begins with the fundamental physics of Pascal's Law, tracing its application through the internal workings of a cylinder, including the barrel, piston, rod, and seals. A typology of cylinders—boom, arm, bucket, and the often-overlooked track adjuster cylinder—is presented, detailing their specific roles in the machine's overall function. The discourse then transitions to a diagnostic framework, identifying five primary indicators of hydraulic cylinder failure: fluid leakage, diminished operational power, anomalous auditory and vibratory signals, overt physical damage, and uncontrolled cylinder drift. For each failure sign, the underlying causes are explored, alongside preventative maintenance strategies and cost-effective solutions tailored to the demanding operational environments found in Africa, Australia, the Middle East, and Southeast Asia.

Key Takeaways

  • Regularly inspect cylinders for any signs of fluid leaks, which indicate seal failure.
  • Monitor for sluggish operation or power loss, as this can signal internal bypassing.
  • Listen for unusual noises like hissing or knocking, which point to aeration or cavitation.
  • Check for bent rods or barrel damage, as physical harm compromises cylinder integrity.
  • Test for cylinder drift to prevent unintended movement and ensure operational safety.
  • Choosing high-quality hydraulic cylinders for excavators reduces long-term operational costs.
  • Proper track tension, managed by the track adjuster cylinder, is vital for undercarriage life.

Table of Contents

The Heart of the Machine: Understanding Hydraulic Cylinders for Excavators

To truly comprehend the immense capability of an excavator, one must look beyond its imposing steel frame and consider the source of its power. The machine's ability to dig, lift, and move tons of earth with such precision does not spring from its engine alone. Instead, the engine's primary role is to power a hydraulic pump. This pump is the heart of a complex circulatory system, and the hydraulic cylinders are the muscles. These cylinders are the actuators that convert the latent energy of pressurized fluid into raw, controllable mechanical force (Hidroman.com.tr, 2025). Without them, an excavator would be little more than a static monument of steel. Understanding their function is the first step toward mastering excavator maintenance and ensuring long-term operational viability.

What Are Hydraulic Cylinders and Why Are They So Powerful?

At its core, a hydraulic cylinder is a linear actuator. It takes hydraulic energy—in the form of pressurized oil—and transforms it into a push or pull motion along a straight line. The principle that underpins this remarkable transformation is a cornerstone of fluid mechanics known as Pascal's Law. Articulated by the French mathematician and physicist Blaise Pascal in the 17th century, this law states that pressure applied to a confined, incompressible fluid is transmitted undiminished to every portion of the fluid and the walls of the containing vessel (Automation Distribution, 2024).

Let's imagine this in a simpler context. Think of two connected syringes, one small and one large, both filled with water. If you apply a small force to the plunger of the small syringe, you create pressure in the water. According to Pascal's Law, that same pressure is exerted on the larger plunger in the second syringe. Because the area of the larger plunger is much greater, the resulting force it exerts is magnified proportionally. A small push on one end creates a much larger push on the other.

A hydraulic cylinder operates on this very principle of force multiplication. The hydraulic pump sends a flow of oil into the cylinder, creating pressure against a piston. Even a moderate system pressure, when applied over the large surface area of the piston head, can generate immense output forces—often hundreds of thousands of newtons. This is how an excavator can effortlessly lift massive boulders or tear through compacted soil. The system is designed to trade fluid volume and flow for immense, controllable force.

The Core Components: A Look Inside the Cylinder

While the principle is elegant, the physical object is a marvel of engineering, designed to withstand extreme pressures and harsh conditions. To diagnose problems and appreciate their function, we must understand their anatomy.

  • Cylinder Barrel: This is the main body of the cylinder, a seamless thick-walled tube, typically honed to a smooth internal finish. Its primary function is to contain the pressure of the hydraulic fluid. The integrity of the barrel is paramount; any scoring or damage to the internal surface can compromise the seals and lead to failure.
  • Piston: The piston is a cylindrical disc that fits snugly inside the barrel, dividing it into two chambers: the head-end chamber and the rod-end chamber. It is the component that the pressurized fluid acts upon to create movement (Zeus Hydratech Ltd, 2025).
  • Piston Rod: This is a hard, chrome-plated shaft attached to one side of the piston. It extends out of the barrel and connects to the part of the machine that needs to be moved, such as the arm or bucket. The quality of the chrome plating is vital for resisting corrosion and wear, which could otherwise damage the rod seal.
  • Cylinder Head and Cap: These are the end caps of the cylinder barrel. The cylinder head (or gland) is where the piston rod passes through. It contains the rod seal, wiper seal, and rod bearing. The cap (or base) seals the other end of the barrel.
  • Seals: Perhaps the most delicate yet vital components, seals prevent fluid from leaking. There are two primary types. Piston seals prevent fluid from bypassing the piston from one chamber to the other. Rod seals prevent fluid from leaking out of the cylinder along the piston rod. A wiper seal, located on the outermost part of the cylinder head, cleans the piston rod as it retracts, preventing contaminants like dust and moisture from entering the system.

Each component works in concert. Fluid pumped into the head-end chamber pushes the piston, extending the piston rod to perform work. To retract the rod, fluid is pumped into the rod-end chamber, pushing the piston in the opposite direction. This elegant, powerful dance of fluid and steel is repeated thousands of times a day on a working excavator.

The Symphony of Movement: How Boom, Arm, and Bucket Cylinders Work Together

An excavator's digging arm is not a single rigid piece but a series of articulated components: the boom (closest to the cab), the arm (or stick), and the bucket. Each of these is actuated by its own set of hydraulic cylinders, and their coordinated movement creates the machine's impressive range of motion.

Imagine the operator wanting to dig a trench. First, they might extend the arm cylinder while keeping the boom and bucket cylinders static, pushing the bucket away from the machine. Then, they lower the boom by retracting the boom cylinders, plunging the bucket teeth into the ground. Next comes the powerful scooping motion, achieved by retracting the arm cylinder and curling the bucket by retracting the bucket cylinder. The three sets of cylinders work in a synchronized ballet, controlled by the operator's inputs through the hydraulic control valves. This coordination allows for not just powerful digging but also the delicate grading and positioning required for finishing work. Understanding this interplay is key to recognizing when one cylinder's poor performance is affecting the entire digging cycle.

A Closer Look at the Types of Excavator Hydraulic Cylinders

While they all operate on the same fundamental principles, the hydraulic cylinders on an excavator are not a one-size-fits-all component. They are specifically designed and sized for their unique tasks, bearing different loads and performing distinct movements. A comprehensive understanding of these types is essential for correct diagnosis, repair, and replacement. The primary cylinders are those that control the main digging attachment, but we must not forget the crucial cylinder hidden within the undercarriage.

Boom Cylinders: The Foundation of Lifting Power

The boom cylinders are typically the largest and most powerful hydraulic cylinders on an excavator. Usually mounted in pairs on either side of the operator's cab, they connect the machine's main frame to the boom—the first and largest section of the digging arm. Their sole purpose is to lift and lower the entire boom assembly. When these cylinders extend, the boom rises; when they retract, the boom lowers.

Because they are responsible for lifting the combined weight of the arm, bucket, and the material within the bucket, these cylinders must generate and withstand enormous forces. They are the primary determinants of the excavator's lifting capacity. A failure in a boom cylinder is not just an inconvenience; it can be a major safety hazard, potentially leading to the uncontrolled collapse of the entire front attachment. Their robust construction reflects this, with thick barrels, large-diameter piston rods, and heavy-duty seals designed for maximum load-bearing capability.

Arm (Stick) Cylinders: The Reach and Precision

Mounted on top of the boom, the arm cylinder (often called the stick cylinder) controls the movement of the arm, the second section of the digging apparatus. This single, long cylinder provides the "in and out" motion of the digging cycle, extending to push the bucket away and retracting to pull it back towards the cab.

The arm cylinder is what gives the excavator its reach. Its long stroke length allows the operator to position the bucket over a wide working arc. It also provides a significant portion of the digging force, known as breakout force, by pulling the bucket through the material. The speed and responsiveness of this cylinder are critical for fast cycle times and efficient material loading. Any sluggishness or hesitation in the arm cylinder's movement will be immediately noticeable to an experienced operator and will directly impact productivity.

Bucket Cylinders: The Digging and Scooping Force

The bucket cylinder is the smallest of the three main attachment cylinders, but its role is no less important. It is mounted on the arm and connects to the bucket via a linkage mechanism. This cylinder is responsible for the curling and uncurling motion of the bucket.

When the bucket cylinder retracts, it pulls on the linkage, causing the bucket to curl inwards for a scoop. When it extends, it pushes the linkage, causing the bucket to uncurl or dump its load. This cylinder provides the final, critical component of the excavator's breakout force, prying material loose from the ground. It must be powerful and fast-acting to ensure a full bucket on every pass and a quick dump when loading trucks. The linkages it operates through are subject to high stress and wear, so inspections should include not just the cylinder but also the associated pins and bushings.

The Unsung Hero: The Track Adjuster Cylinder in the Undercarriage

Far from the visible action of the digging arm lies another vital hydraulic cylinder: the track adjuster. This component is part of the track tensioning system within the excavator's undercarriage. Its function is not to lift or dig, but to maintain the correct tension on the machine's tracks. Housed within the track frame, the track adjuster consists of a hydraulic cylinder filled with grease (which acts as the hydraulic fluid in this application) and a large recoil spring assembly.

The cylinder's piston rod pushes against the front idler yoke, moving the idler wheel forward or backward to tighten or loosen the track chain. Proper track tension is a delicate balance. Too loose, and the track can come off the rollers (derail), causing significant downtime and potential damage. Too tight, and it creates immense friction and stress, causing accelerated wear on all undercarriage components, including the track chain, track roller, carrier roller, and the sprocket segment. The track adjuster cylinder allows for this precise adjustment and also works with the recoil spring to absorb shocks and impacts encountered during travel, protecting the entire undercarriage. A leaking or failing track adjuster cylinder will make it impossible to maintain proper tension, leading to costly and premature undercarriage failure.

Table 1: Comparison of Excavator Cylinder Functions

Cylinder Type Primary Location Main Function Key Performance Metric Common Failure Impact
Boom Cylinder Main frame to boom Lifts and lowers the entire boom assembly Lifting Capacity Loss of lifting power; potential for boom collapse
Arm (Stick) Cylinder Boom to arm Extends and retracts the arm for reach Cycle Speed & Reach Slow operation; reduced digging arc and breakout force
Bucket Cylinder Arm to bucket linkage Curls and uncurls the bucket for digging/dumping Breakout Force Inability to scoop effectively or hold a load
Track Adjuster Cylinder Inside the track frame Maintains proper tension of the track chain Track Tension Inability to hold tension, leading to track derailment or accelerated undercarriage wear

The First Critical Failure Sign: Visible Hydraulic Fluid Leaks

Among the various symptoms of distress a hydraulic cylinder can exhibit, a visible fluid leak is the most direct and unambiguous. It is a clear signal that the integrity of the sealed system has been breached. While a small drip of oil on the ground might seem minor, it should never be ignored. A leak is not just a mess; it is a symptom of an underlying problem, a drain on efficiency, and a potential precursor to catastrophic failure. The fluid leaving the system is a loss of the very lifeblood that enables the machine to perform work.

Pinpointing the Source: Rod Seals vs. Piston Seals

When you see hydraulic oil on the exterior of a cylinder, the most common culprit is a failed rod seal. The rod seal is housed in the cylinder head (or gland) and is designed to prevent fluid from escaping the cylinder as the piston rod extends and retracts. Over time, these seals can wear down due to friction, age, or exposure to contaminants. A damaged piston rod—one that is scratched, pitted, or bent—can act like a file, rapidly destroying a new rod seal. The wiper seal, which is the first line of defense against external dirt, can also fail. When it does, abrasive particles are drawn into the cylinder, where they can damage the rod seal from the inside.

A leak is most often seen as a film of oil on the extended piston rod or as drips coming from the cylinder gland. It is a leak to the outside world.

A far more insidious type of leak is an internal one, caused by a failed piston seal. These seals are mounted on the piston and are meant to prevent fluid from "bypassing" from the high-pressure side of the piston to the low-pressure side. When a piston seal fails, fluid leaks internally from one chamber to the other. There is no visible external drip, but the cylinder's performance will be severely compromised. It will lose its ability to hold a load or will move sluggishly under pressure. This is often referred to as "internal bypass" or "blow-by" and will be discussed further as a cause of power loss. For now, the key distinction is that external leaks (rod seal failure) are visible, while internal leaks (piston seal failure) are invisible but felt in performance.

The Hidden Dangers of Minor Leaks

It can be tempting for an operator or fleet manager, especially in high-pressure work environments, to dismiss a small leak as a low-priority issue. This is a costly mistake. Let's consider the cascading consequences.

First is the direct cost of the lost fluid. Hydraulic oil is a significant operational expense, and even a leak of a few drops per minute adds up to many liters over weeks and months. Second is the loss of system efficiency. As fluid leaks out, the pump must work harder to maintain the required pressure, consuming more fuel and putting extra strain on itself and other components.

More importantly, a leak is a two-way street. If fluid can get out, contaminants can get in. Dust, dirt, and moisture are the enemies of a hydraulic system. Once inside, these particles act as an abrasive slurry, accelerating wear on pumps, valves, and the internal surfaces of the cylinders themselves. Water contamination can lead to corrosion, fluid degradation, and reduced lubricity. A minor rod seal leak can quickly introduce enough contamination to jeopardize the entire multi-thousand-dollar hydraulic system. Ignoring it is like leaving a wound open to infection.

Environmental and Safety Implications in African and Australian Contexts

In many of the regions where heavy excavation work is common, such as the mining sites of Western Australia or the large-scale construction projects across Africa and the Middle East, environmental regulations are increasingly stringent. A hydraulic fluid leak is not just a maintenance issue; it is an environmental spill. A single liter of hydraulic oil can contaminate thousands of liters of groundwater. Fines for soil and water contamination can be substantial, and the reputational damage to a company can be even more severe. Proactive leak management is a core part of responsible environmental stewardship on any job site.

Beyond the environmental concerns are direct safety risks. Leaking hydraulic fluid can create slip hazards for personnel working around the machine. More critically, if the leak is significant, it can lead to a sudden loss of hydraulic pressure, causing a suspended load to drop unexpectedly. Imagine a boom cylinder failing while lifting a heavy pipe over a work crew. The consequences could be tragic. Furthermore, hydraulic fluid is flammable and can be atomized into a fine mist when leaking under high pressure. If this mist comes into contact with a hot surface, such as an engine manifold or a turbocharger, it can ignite with explosive force, creating a serious fire hazard.

The Second Critical Failure Sign: Loss of Power and Sluggish Operation

While a leak is a visible cry for help, a loss of power is a more subtle, yet equally serious, symptom of a failing hydraulic cylinder. The excavator may feel "weak" or "lazy." It might struggle to lift loads it once handled with ease, or its movements may become slow and unresponsive. This decline in performance directly translates to lost productivity. Slower cycle times mean fewer trucks loaded per hour, less earth moved per day, and ultimately, a negative impact on the project's bottom line. This symptom points to a problem with the cylinder's ability to efficiently convert fluid pressure into mechanical force.

Diagnosing Internal Bypass: When Fluid Goes the Wrong Way

The most common cause of a strong-but-sluggish cylinder is internal bypass, also known as piston seal failure. As mentioned earlier, the piston seal is what separates the two chambers inside the cylinder. For the cylinder to generate force, the hydraulic fluid must be contained on one side of the piston, pushing against it. When the piston seal is worn, damaged, or degraded, a pathway is created for the high-pressure oil to leak past the piston into the low-pressure chamber on the other side.

Think of it like trying to inflate a tire with a leaky valve. The pump (the air compressor) is working hard, but much of the air (the fluid) is escaping instead of building pressure inside the tire (the cylinder). In the excavator, the hydraulic pump is still delivering its full flow of oil, but because of the internal leak, not all of that flow is being used to move the piston. The result is a loss of speed and force. The cylinder struggles to move under load because the pressure difference across the piston cannot be effectively maintained. This condition generates a significant amount of heat as the high-pressure fluid is forced through the small gap past the seal, which can further degrade the hydraulic oil and damage other components.

A simple field test can often diagnose severe internal bypass. For a double-acting cylinder like a bucket cylinder, you can fully extend it and then disconnect the hydraulic hose from the rod-end port. Then, with the machine at idle, carefully apply pressure to the head-end port (as if trying to extend it further). If oil flows out of the disconnected rod-end port, it is a clear sign that the piston seal is leaking internally.

The Ripple Effect: How a Weak Cylinder Impacts Productivity

The impact of a single weak cylinder reverberates throughout the entire operational cycle of the excavator. Let's consider an excavator loading trucks with soil.

If the bucket cylinder is weak due to internal bypass, the operator may struggle to get a full bucket on each pass. The bucket may fail to penetrate hard ground or may not have the force to curl completely, leaving half the material behind. This requires extra passes to fill the bucket, extending the digging portion of the cycle.

If the arm cylinder is sluggish, pulling the filled bucket in towards the machine and slewing over the truck will take longer. The movement will lack the crisp, responsive feel of a healthy machine.

If the boom cylinders are weak, lifting the heavy, loaded bucket to the height of the truck's sideboard will be a slow, labored process. The engine may strain as the hydraulic system struggles to build the necessary pressure.

Each of these individual delays—a few seconds on the dig, a few on the swing, a few on the lift—adds up. Over the course of an eight-hour shift, these lost seconds can amount to several fewer trucks loaded. In a production-focused environment like a mine or a large earthmoving project, this loss of productivity can represent thousands of dollars in lost revenue or project delays each day. The weak cylinder becomes a bottleneck for the entire operation.

Case Study: A Mining Operation in the Pilbara

Imagine a fleet of excavators working at a large iron ore mine in the Pilbara region of Western Australia. The environment is harsh: extreme heat, abrasive red dust, and a relentless production schedule. One of the primary loading excavators begins to show signs of sluggishness. Its cycle times, which are meticulously tracked, have increased by 15%. The operator reports that the machine "just doesn't have the grunt" it used to.

Initial checks find no external leaks and the engine seems to be running fine. The maintenance team suspects an internal hydraulic issue. They focus on the arm cylinder, as the "pulling" phase of the dig seems to be the slowest. Using a thermal camera, they notice the arm cylinder's barrel is significantly hotter than the boom or bucket cylinders, a classic sign of heat generation from internal bypassing.

They decide to swap out the suspect arm cylinder with a rebuilt unit. The change is immediate. The excavator's cycle times return to normal, and the operator reports the machine feels powerful and responsive again. Upon disassembly of the old cylinder, they find the piston seal was severely worn and brittle, likely due to a combination of high operating temperatures and contamination from the fine, abrasive dust. By diagnosing and addressing the single failing cylinder, they restored the productivity of a multi-million dollar asset and prevented a potential cascade of further hydraulic system damage. This example underscores the economic imperative of addressing sluggish performance promptly.

The Third Critical Failure Sign: Unusual Noises and Vibrations

An experienced operator develops an intimate feel for their machine. They know its normal hums, whirs, and clunks. When a new, unusual noise or vibration appears, it is often the first sign that something is amiss within the hydraulic system. These auditory and tactile signals are not random; they are diagnostic clues that can help pinpoint specific problems, often before they cause major damage. Hissing, knocking, or grinding sounds emanating from or near a hydraulic cylinder should be investigated immediately.

Decoding the Sounds: Knocking, Hissing, and Grinding

Each sound tells a different story about what might be happening inside the complex hydraulic circuit.

  • Hissing: A loud hissing sound, especially when a cylinder is under load or reaches the end of its stroke, is often the sound of high-pressure fluid passing through a small orifice. This could be the sound of the main relief valve opening, which is normal if the cylinder is stalled at the end of its stroke. However, if it occurs during movement, it can be the sound of significant internal bypassing past a failed piston seal. The fluid is essentially "squeezing" through a gap it shouldn't be, creating audible turbulence.
  • Knocking or Banging: A sharp knocking or banging sound, particularly when a cylinder changes direction or starts and stops a movement, can indicate several issues. It might be caused by air trapped in the cylinder. Air is compressible, unlike oil, so it can cause jerky, uncontrolled movements that result in mechanical shock. The sound could also come from worn mechanical components, such as the pins and bushings that connect the cylinder to the excavator's frame and arm. Excessive play in these connections will cause a "clunk" as the load shifts. In severe cases, it could even be the piston itself physically striking the end caps of the cylinder due to a cushioning failure.
  • Grinding or Groaning: A grinding or groaning noise is a particularly worrying sign. This often indicates severe mechanical wear or major contamination. The sound could be caused by metallic particles from a failing pump or another component being circulated through the system and getting ground up inside the cylinder. It could also suggest that the piston or piston rod is making metal-to-metal contact with the cylinder barrel or gland due to a failure of the bearing surfaces. Operating a cylinder that is making a grinding noise is likely to be causing rapid and catastrophic internal damage.

The Culprit of Cavitation and Aeration

Two specific conditions, aeration and cavitation, are common sources of noise and are extremely destructive to hydraulic components.

Aeration is the presence of dissolved or entrained air bubbles in the hydraulic fluid. This can happen if there is a leak on the suction side of the pump (e.g., a loose intake hose clamp), or if the fluid level in the hydraulic reservoir is too low, allowing the pump to draw in air along with the oil. This aerated oil, when compressed, causes the air bubbles to collapse violently, creating noise, vibration, and erratic cylinder movement. The cylinders may seem to "jump" or "shudder" as they move.

Cavitation is a more complex phenomenon. It occurs when the pressure in a part of the hydraulic circuit drops below the vapor pressure of the fluid. This can happen if there is a restriction or blockage that "starves" the pump or cylinder of fluid. In these low-pressure areas, the oil literally boils at the ambient temperature, forming vapor-filled cavities or bubbles. As these bubbles travel to a higher-pressure area (like the outlet side of the pump or inside the cylinder under load), they implode with tremendous force. This implosion is what creates a high-frequency knocking or rattling sound. Each implosion acts like a tiny hammer blow, capable of eroding and pitting the hardened steel surfaces of valves, pump components, and cylinder walls over time. Cavitation is silent but deadly to a hydraulic system.

How Contamination Affects the Entire Hydraulic System

The noises and vibrations are often symptoms of a system-wide problem: contamination. The hydraulic system of an excavator is a closed loop. This means that any contaminant introduced at one point will be circulated throughout the entire system. A failing pump can shed metal particles that will travel to every valve and every cylinder. A leaking cylinder can introduce dust and water that will travel back to the reservoir and then be sent through the pump.

This is why a single noisy cylinder cannot be viewed in isolation. It may be the victim of a problem that originated elsewhere, or it may be the source of contamination that is about to destroy other expensive components. When a cylinder fails and is replaced, it is absolutely vital to also flush the entire hydraulic system and replace the filters. Installing a brand new or rebuilt cylinder into a contaminated system is a recipe for a repeat failure in a very short time. The health of the entire system depends on the cleanliness of the fluid, and unusual noises are often the first audible sign that the fluid is no longer clean.

Table 2: Common Noises and Their Potential Causes

Audible Symptom Potential Cause(s) Associated Risks Recommended Action
Loud Hissing Relief valve operation (normal at end-of-stroke); Severe internal piston seal leak. Reduced efficiency, heat generation, eventual loss of power. Investigate if sound occurs during mid-stroke; test for internal bypass.
Knocking / Banging Air in the system (aeration); Worn cylinder mounting pins/bushings; Cushioning failure. Erratic/jerky movement, shock loads, mechanical damage. Bleed the system; inspect all mechanical connection points for play.
Rattling / Grinding Severe fluid contamination (metal particles); Pump cavitation; Major internal mechanical failure. Rapid destruction of components, catastrophic system failure. Stop operation immediately. Analyze fluid, inspect filters, identify source.
Squealing / Whining Aeration (air being drawn into the pump); Clogged suction strainer/filter. Pump damage, system-wide aeration, component failure. Check fluid level, inspect all suction lines and connections for leaks.

The Fourth Critical Failure Sign: Physical Damage to the Cylinder

Unlike internal issues that manifest as noise or power loss, physical damage to a hydraulic cylinder is an overt and undeniable problem. A bent piston rod or a dented barrel is not something that can be ignored or "worked through." Such damage immediately compromises the cylinder's function and structural integrity, posing a significant safety risk. This type of failure is almost always caused by external forces, either from operational error or an impact with an object on the job site.

Bent Rods and Dented Barrels: Causes and Consequences

A bent piston rod is a common and serious form of damage. Piston rods are designed to handle immense axial (push/pull) loads, but they have very little resistance to side-loading. A rod can be bent if the excavator is used to apply a side force with the bucket, such as trying to pry a large rock sideways instead of digging it out. It can also happen if the attachment strikes an immovable object while in motion. Even a slight bend in the rod can have disastrous consequences. As the bent rod tries to retract into the cylinder, it will exert massive side pressure on the rod bearing and the rod seal in the cylinder gland. This will rapidly destroy both components, causing a major external leak. If the bend is severe enough, the rod may jam completely, or it could score the internal surface of the cylinder barrel, leading to a complete and irreparable failure of the cylinder. A bent rod cannot be straightened; it must be replaced.

A dented barrel is another form of critical damage. The cylinder barrel is a precision-honed tube with a perfectly round and smooth internal surface. If the outside of the barrel receives a sharp impact from a rock, another piece of equipment, or by being dropped during maintenance, it can create a dent. This dent will protrude into the interior of the barrel. As the piston travels down the bore, it will collide with this internal protrusion. At best, this will shave material off the piston seals and bearing strips, leading to rapid internal bypassing. At worst, the piston could seize completely inside the barrel, locking the cylinder in place. A significantly dented barrel usually means the entire cylinder is scrap, as re-honing the inside diameter to remove the damage would make it oversized for the piston.

The Threat of Corrosion in Coastal and Humid Environments

In regions like Southeast Asia or coastal parts of Australia and Africa, high humidity and salt-laden air present a constant threat of corrosion. The piston rod is particularly vulnerable. The rod is protected by a thin layer of hard chrome plating. While this plating is very durable, it can be compromised by a scratch or a chip from an impact.

Once the base steel beneath the chrome is exposed, corrosion can begin. It will often start as a small speck of rust, but it can quickly spread, especially under the chrome layer, causing it to flake off. A pitted or rusted piston rod surface will act like sandpaper on the rod seal every time the cylinder cycles, quickly leading to a hydraulic leak. In these corrosive environments, daily inspections and cleaning of the piston rods are vital. Any exposed rods should be kept greased when the machine is parked for extended periods to protect them from atmospheric moisture. Choosing high-quality boom arm and bucket cylinders with superior chrome plating thickness and quality is a wise investment for operations in these challenging climates.

Inspecting the Supporting Cast: Pins, Bushings, and Mounts

The hydraulic cylinder does not work in isolation. It is connected to the machine's structures via large, hardened steel pins that pass through bushings (or bearings) in both the cylinder eyes and the machine's frame or arm. These connections are designed to allow the cylinder to pivot as it moves.

Over time, these pins and bushings wear down due to the immense forces and constant movement. When they wear, they create "play" or "slop" in the joint. This excessive movement is detrimental. It causes shock loading every time the direction of force changes, sending jarring impacts through the cylinder, its seals, and the machine's structures. This can accelerate the failure of the cylinder itself. A worn pin joint at the base of a boom cylinder can cause the entire boom to visibly jump when it begins to lift a load.

Therefore, any inspection of a hydraulic cylinder must also include a thorough inspection of its mounting points. Check for signs of excessive movement by having an assistant gently operate the controls while you observe the joints. Look for grease being squeezed out of the joint, which can indicate movement. Worn pins and bushings should be replaced as a set to restore the joint to its original tight tolerances. Ignoring worn pins is a false economy, as it will inevitably lead to much more expensive repairs to the cylinder or the machine's steel structures down the line.

The Fifth Critical Failure Sign: Cylinder Drifting or Lack of Holding Power

One of the most unsettling and potentially dangerous failure modes of a hydraulic system is "cylinder drift." This is the term for when a cylinder, under a static load, slowly moves without any command from the operator. For example, the operator may raise the boom and arm to a certain height and then release the controls, expecting the attachment to stay perfectly still. If, over the course of a few minutes, the boom slowly creeps downwards, that is cylinder drift. This indicates that the hydraulic system is failing to lock the fluid in place to hold the load.

Understanding Cylinder Drift: A Slow but Costly Problem

Cylinder drift is a clear sign that hydraulic oil is leaking from the load-bearing chamber of the cylinder. This leak can be happening in one of two places.

The first possibility, as discussed previously, is an internal bypass across the piston seal. If the boom is being held up by pressure in the head-end of the boom cylinders, a leaking piston seal will allow that oil to slowly seep into the rod-end chamber. As the volume of oil in the load-bearing chamber decreases, the boom will slowly drift down. The speed of the drift is directly proportional to the severity of the leak. A slow drift might be caused by a slightly worn seal, while a rapid drift indicates a catastrophic seal failure.

The second common cause is a leaking load-holding valve. These valves are a critical safety and operational component in the hydraulic circuit.

The Role of Load-Holding Valves

A load-holding valve (also known as a counterbalance valve or over-center valve) is a component that is often mounted directly on, or very close to, the hydraulic cylinder. Its purpose is to lock the fluid in the cylinder and prevent the load from running away or drifting down.

Think of it as a one-way check valve with a pilot-operated release. When the operator commands the boom to lift, the pump sends fluid through the valve into the cylinder. When the operator releases the control, the valve closes, trapping the fluid in the cylinder and holding the boom up, even if the main control valve in the cab has a slight leak. To lower the boom, the operator's command does two things: it directs fluid to the other side of the cylinder (the rod end), and it also sends a small "pilot" pressure signal to the load-holding valve, telling it to open and allow the fluid to exit the load-bearing chamber in a controlled manner.

If the seat inside this load-holding valve becomes worn, damaged, or contaminated with a piece of debris, it will not be able to seal perfectly. It will allow a small amount of oil to leak out of the cylinder, resulting in drift. Therefore, when diagnosing a drifting cylinder, it's vital to determine whether the fault lies with the cylinder's internal piston seal or with the external load-holding valve.

Testing for Drift: A Simple Field Diagnostic

A simple diagnostic procedure can help differentiate between a leaking piston seal and a leaking load-holding valve. Let's use the boom cylinders as an example.

  1. Safety First: Perform this test in a clear, open area with no personnel near the machine.
  2. Load the System: Lift the boom and arm so they are off the ground, carrying only their own weight. For a more definitive test, you can add a weight to the bucket (e.g., a full scoop of soil).
  3. Position and Mark: Raise the boom to a convenient height and shut down the engine. To accurately measure drift, place a block under the bucket or make a mark on the ground at the tip of a bucket tooth.
  4. Observe and Measure: Wait for a set period, for instance, 5 to 10 minutes. Measure how far the bucket has drifted down from its original position. This gives you a baseline for the total system drift.
  5. Isolate the Cylinder: Now, to test if the piston seal is the cause, you need to support the load mechanically. The safest way is to lower the boom onto sturdy, rated safety stands or blocks. With the load supported, the pressure in the cylinders drops to zero. Now, restart the machine and retract the boom cylinders just enough to lift the boom slightly off the blocks, then immediately shut down the engine again. If the boom now holds its position without drifting, it strongly suggests the problem is not the piston seal, but rather the load-holding valve, because the valve was the only thing holding the boom up in this scenario. If the drift was still present even with the load supported, the problem is more complex, possibly involving the control valve.

More simply, if a cylinder drifts under a load but the load-holding valve is known to be good (or has been recently replaced), the suspicion falls squarely on the cylinder's internal piston seals. Swapping the load-holding valves between the two boom cylinders (if they are identical) is another way to see if the problem follows the valve.

Proactive Maintenance and Cost-Saving Strategies

Reacting to failures as they occur is a costly way to manage a fleet of excavators. A bent rod or a seized cylinder results in immediate and often extensive downtime, along with expensive emergency repairs. A far more effective and economical approach is proactive maintenance. This philosophy is centered on regular inspections, preventative actions, and intelligent decision-making to address small problems before they escalate into catastrophic failures. For operators in demanding markets, a robust maintenance program is not an expense; it is an investment in uptime, safety, and profitability.

The Importance of a Rigorous Inspection Schedule

The foundation of any proactive maintenance program is a schedule of regular, systematic inspections. These checks should be part of the daily routine for the operator and supplemented by more in-depth inspections by maintenance personnel.

  • Daily Walk-Around: Before starting each shift, the operator should perform a visual inspection of the entire machine, with a special focus on the hydraulic cylinders. This includes looking for any signs of oil leaks on the rods, around the glands, or on the ground beneath the machine. They should check the exposed piston rods for any nicks, scratches, or signs of corrosion. Any visible damage should be reported immediately.
  • Weekly Checks: Once a week, a more thorough check is warranted. This involves cleaning the cylinders to get a better look at their condition. All cylinder mounting pins and bushings should be greased according to the manufacturer's schedule to purge contaminants and ensure smooth pivoting. While greasing, check the joints for any excessive play or movement.
  • Functional Tests: During operation, the operator should remain attentive to the machine's performance. Is the movement smooth and responsive? Is there any new noise or vibration? Does the machine feel as powerful as it should? Testing for cylinder drift under load should be performed periodically as a health check.

This culture of diligent inspection allows for the early detection of issues like a weeping seal, a small scratch on a rod, or the beginning of wear in a pin joint. Addressing these minor issues early—by replacing a seal kit, polishing a minor rod imperfection, or replacing a worn bushing—is exponentially cheaper than replacing an entire cylinder that has failed catastrophically.

Managing Hydraulic Fluid Health: Filtration and Analysis

The hydraulic fluid is the lifeblood of the system. Its condition is the single most important factor in the longevity of the cylinders, pumps, and valves. Maintaining fluid health involves two key practices: filtration and analysis.

Filtration: Every hydraulic system is equipped with filters designed to capture contaminants. The main return line filter is the most critical, as it cleans the oil before it goes back to the reservoir. Suction strainers protect the pump, and high-pressure filters may be used in some circuits. These filters are not permanent; they have a limited capacity. Following the manufacturer's recommended replacement interval is essential. Extending filter service intervals is a false economy that allows damaging particles to circulate freely through the system. In particularly dusty environments, such as those found in many parts of the Middle East and Africa, it may be wise to shorten the filter replacement interval.

Fluid Analysis: The most advanced form of proactive maintenance is regular oil sampling and analysis. A small sample of hydraulic fluid is taken from the system and sent to a laboratory. The lab report provides a wealth of information. It can identify the type and quantity of contaminants (e.g., dirt, water, metal particles), telling you if your filtration is effective or if a component is wearing abnormally. For example, high levels of brass or bronze might point to a failing pump, while high levels of silicon (dirt) indicate a problem with air filtration or seals. The analysis also checks the chemical properties of the oil itself—its viscosity, acidity, and the condition of its additive package. This data allows you to change the oil based on its actual condition, rather than just on hours of service, and provides an early warning of impending component failure.

The Repair vs. Replace Dilemma: Making the Right Financial Decision

When a hydraulic cylinder fails, the fleet manager is faced with a choice: repair the existing cylinder or replace it with a new or rebuilt unit. The correct decision depends on the nature of the failure and a careful cost-benefit analysis.

A simple reseal, where the cylinder is disassembled, cleaned, inspected, and reassembled with a new seal kit, is often the most cost-effective option for leaks or minor internal bypassing. This can usually be done for a fraction of the cost of a new cylinder.

However, if the failure involves major component damage—such as a bent or deeply scored rod, a scratched barrel, or damaged piston—the cost of the repair can escalate quickly. The cost of a new piston rod, plus the labor to disassemble and reassemble the unit, may approach the cost of a fully rebuilt exchange cylinder. In this case, replacement is often the better choice. A rebuilt cylinder can be installed quickly, minimizing machine downtime, and it typically comes with a warranty. The failed cylinder can then be sent away to be repaired as a spare.

For critical damage like a dented or scored barrel, repair is often not feasible or economical. The only viable option is replacement. Investing in choosing reliable excavator hydraulic cylinders from a reputable supplier ensures that you are getting a component that meets or exceeds original specifications, providing peace of mind and long-term reliability.

Choosing High-Quality Replacement Cylinders

When replacement is necessary, the quality of the new cylinder is paramount. While lower-cost options may be tempting, they often prove more expensive in the long run due to premature failure and increased downtime. A high-quality cylinder is defined by the quality of its materials and manufacturing. This includes a barrel made from steel suitable for honing to a fine finish, a piston rod made from high-tensile steel with thick, flawless chrome plating, and high-quality seals from reputable manufacturers designed to withstand high pressures and temperatures. Making the right choice in a replacement part is a critical cost-saving strategy.

The Role of the Undercarriage and the Track Adjuster Cylinder

While much of the focus on an excavator's hydraulic system is on the boom, arm, and bucket functions, the undercarriage contains a hydraulic component that is fundamental to the machine's mobility and operational longevity: the track adjuster cylinder. The undercarriage of an excavator represents a significant portion of the machine's total value and its ongoing maintenance costs. The proper function of the track adjuster cylinder is inextricably linked to the health and lifespan of every other undercarriage component.

Maintaining Correct Track Tension: A Balancing Act

The track chain of an excavator is a heavy, articulated belt of steel links, pins, and bushings. For the machine to move efficiently and for the undercarriage to wear evenly, this chain must be maintained at a specific tension, commonly referred to as "track sag."

This tension is a delicate balance. If the track is too loose, it will flap and vibrate as the machine moves. This can cause the track to "derail" or walk off the front idler or rollers, an event that brings the machine to an immediate halt and requires significant effort and time to correct. A loose track also fails to engage properly with the sprocket segment, leading to slipping and accelerated wear on the sprocket teeth and the track chain's internal bushings.

Conversely, if the track is too tight, it creates an enormous, continuous strain on the entire system. The friction between the track chain's internal pins and bushings increases dramatically, causing them to wear out at a highly accelerated rate. This tightness also puts immense pressure on the bearings within the track roller and carrier roller components, as well as the front idler bearings. A tight track effectively robs the engine of power, increases fuel consumption, and can literally tear the undercarriage apart from the inside out.

How the Track Adjuster Cylinder Works

The track adjuster is the mechanism that allows for the precise setting and maintenance of this critical track tension. It consists of two main parts working together: a large recoil spring and a hydraulic cylinder. In this application, the cylinder is typically filled with grease rather than oil, but it functions hydraulically.

The recoil spring is a heavy-duty compression spring that acts as a shock absorber. It allows the front idler to momentarily move backward if the track encounters a large rock or obstacle, preventing the shock load from damaging the undercarriage. The hydraulic cylinder part of the adjuster provides the means of adjustment. It has a fill/release valve, often called a track adjuster valve. To tighten the track, a mechanic uses a grease gun to pump heavy grease into the cylinder. This pushes the cylinder's piston rod out, which in turn shoves the entire front idler assembly forward, increasing the tension on the track chain. To loosen the track, the valve is carefully opened, allowing the high-pressure grease to escape, and the existing tension in the track pushes the idler back, creating more sag.

A failing track adjuster cylinder, one with leaking seals, will be unable to hold the grease pressure. The mechanic will tighten the track to the correct specification, but over a few hours or days of operation, the grease will leak out, and the track will become loose again. This makes proper maintenance impossible and puts the entire undercarriage at risk.

The Interplay Between the Track Adjuster, Front Idler, and Track Chain

These three components form a critical functional group. The track adjuster pushes the front idler, and the front idler guides the track chain. The health of each is dependent on the others.

A faulty track adjuster that cannot maintain tension leads to a loose track chain. This loose chain will not ride smoothly over the front idler, causing abnormal wear patterns on both the idler's running surface and the links of the track chain. The chain may also slap against the track roller and carrier roller components, causing impact damage.

Conversely, a problem with the front idler, such as a seized bearing, will prevent it from rotating freely. As the track is forced to drag across the stationary idler surface, it creates immense friction and strain, putting a backward load on the track adjuster cylinder that it was not designed to handle, potentially causing its seals to fail. The relationship is symbiotic; a failure in one part quickly precipitates wear and damage in the others. Therefore, any undercarriage inspection must assess the track adjuster, front idler, and track chain as an integrated system.

Sourcing and Selecting the Right Hydraulic Cylinders for Excavators

When a hydraulic cylinder fails and repair is not the optimal path, the process of sourcing and selecting a replacement becomes a critical decision point for any machine owner or fleet manager. This choice has significant implications for future reliability, machine uptime, and long-term operational costs. Navigating the market for replacement parts, especially in diverse regions like Africa, Australia, and the Middle East, requires a discerning eye for quality and an understanding of what truly makes a durable cylinder.

Why OEM is Not the Only Option: The Value of Quality Aftermarket Parts

The first decision is often whether to purchase a replacement from the Original Equipment Manufacturer (OEM) or to explore the aftermarket. While OEM parts offer a guarantee of perfect fit and original specification, they often come at a premium price. The high-quality aftermarket, on the other hand, presents a compelling value proposition.

Reputable aftermarket manufacturers often specialize in specific components, such as hydraulic cylinders or undercarriage parts. This focus allows them to invest heavily in research, materials science, and manufacturing processes, sometimes even improving upon the original design. A top-tier aftermarket supplier can produce hydraulic cylinders for excavators that meet or even exceed OEM standards in terms of durability and performance, but at a more competitive price point. The key is to distinguish between high-quality aftermarket suppliers who stand behind their products with robust warranties and rigorous quality control, and low-cost, low-quality producers. For businesses operating on tight margins, the cost savings offered by a reliable aftermarket partner can be substantial without compromising on quality.

Material Science: What Makes a Durable Cylinder?

The longevity of a hydraulic cylinder is determined, above all, by the quality of the materials from which it is made.

  • Cylinder Barrel: The barrel should be made from a "drawn over mandrel" (DOM) steel tube. This process ensures high dimensional accuracy and a smooth internal surface ideal for honing. The steel grade must have the right balance of strength to contain high pressures and ductility to resist cracking.
  • Piston Rod: This is arguably the most critical component for long-term reliability. The base material should be a high-tensile strength, induction-hardened steel to resist bending and impact damage. The most important feature is the chrome plating. A high-quality rod will have a thick layer of hard chrome (often 25 microns or more) that has been meticulously polished. This provides a hard, corrosion-resistant, low-friction surface for the seals to run on. Thin or poorly applied chrome will quickly wear or flake away, especially in harsh environments, leading to rapid seal failure.
  • Piston and Gland: These components are typically made from high-strength ductile iron or steel to withstand the immense pressures and stresses they are subjected to during operation.

When evaluating a potential supplier, one should inquire about the material specifications and manufacturing standards they adhere to. A supplier confident in their quality will be transparent about these details.

Seal Technology: The Key to Longevity

A cylinder is only as good as its seals. Even the best steel components will fail if the seals cannot contain the hydraulic fluid effectively. Modern seal technology is highly advanced, and a premium cylinder will use a multi-part sealing system. This typically includes:

  • Piston Seals: Often made from materials like polyurethane (PU) or polytetrafluoroethylene (PTFE) with an elastomer expander. These are designed to provide excellent wear resistance and sealing capability across a wide range of temperatures and pressures.
  • Rod Seals: Similar materials to piston seals, but often in a U-cup or V-packing configuration to provide a robust seal against the dynamic surface of the rod.
  • Wiper Seals: Located at the very front of the gland, their job is to scrape contaminants off the rod as it retracts. A double-lip wiper provides superior protection by preventing both dirt from entering and oil from weeping out.
  • Bearing/Wear Strips: These are bands of low-friction material (like filled PTFE or acetal) on the piston and in the gland. Their purpose is to support the piston and rod, preventing metal-to-metal contact with the barrel and gland, ensuring smooth movement and absorbing side loads.

A a hallmark of a quality cylinder is the use of seals and bearing strips from globally recognized, reputable manufacturers.

Finding a Reliable Supplier for Africa, Australia, and the Middle East

For customers in these expansive and often remote regions, the logistics of sourcing parts is a major consideration. A reliable supplier is not just one who sells a quality product, but one who can deliver it efficiently and support it effectively. Key factors to consider include:

  • Inventory and Availability: Can the supplier provide the specific cylinder for your make and model of excavator from stock? Long lead times mean extended machine downtime. A supplier with significant local or regional warehousing has a distinct advantage.
  • Logistical Expertise: Does the supplier have experience shipping to your location? Understanding the customs, duties, and transportation challenges in regions across Africa, the Middle East, or remote parts of Australia is vital for ensuring parts arrive on time and without complication.
  • Technical Support and Warranty: A trustworthy supplier will have knowledgeable staff who can help you confirm you are ordering the correct part and can offer technical advice. They will also stand behind their product with a clear and fair warranty policy, giving you confidence in your purchase.

Ultimately, selecting the right cylinder comes down to a partnership with a supplier who understands the demands of your operating environment and is committed to providing a product that delivers both performance and value.

Frequently Asked Questions (FAQ)

What is the main cause of hydraulic cylinder failure on an excavator? The most common causes are seal failure due to age, wear, or contamination, and physical damage to the piston rod (bending or scoring). Contaminated hydraulic fluid is a primary underlying factor that accelerates wear on all components, especially seals.

How often should I replace the hydraulic fluid in my excavator? Follow the manufacturer's recommended service interval as a baseline, which is typically every 2,000 to 4,000 operating hours. However, in harsh, dusty, or hot environments, it's best to rely on regular hydraulic fluid analysis to determine the oil's actual condition and change it when the analysis indicates degradation or high contamination levels.

Can a bent hydraulic cylinder rod be repaired? No, a bent piston rod should never be straightened and reused. The straightening process creates stress fractures and weakens the steel, making it highly susceptible to a complete fracture under load. A bent rod will also have permanently damaged the chrome plating. The only safe and reliable solution is to replace the entire piston rod.

What is the difference between a single-acting and double-acting cylinder? A single-acting cylinder uses hydraulic pressure to extend the rod, but relies on an external force, such as gravity or a spring, to retract it. A double-acting cylinder, which is standard on excavators for boom, arm, and bucket functions, uses hydraulic pressure for both extension and retraction, allowing for powered movement in both directions.

Why is my excavator's track always loose even after I tighten it? This is a classic symptom of a failing track adjuster cylinder. The seals inside the grease-filled cylinder are likely worn or damaged, allowing the grease to leak out under pressure. This prevents the adjuster from holding the front idler in its forward position, causing the track to lose tension over time. The track adjuster cylinder needs to be resealed or replaced.

Is it better to repair or replace a leaking hydraulic cylinder? If the leak is due to seal failure and there is no damage to the rod or barrel, a repair (reseal) is usually the most cost-effective option. If there is significant damage, such as a scored rod or dented barrel, replacing the cylinder with a high-quality new or remanufactured unit is often faster and provides better long-term value.

What are the signs of a worn track adjuster cylinder? The primary sign is the inability to maintain proper track tension. Other signs can include visible grease leaking from the track adjuster valve or from where the adjuster meets the idler yoke. This component is critical for the lifespan of your track chain and sprocket segment.

Conclusion

The hydraulic cylinders for excavators are the embodiment of force and precision, the indispensable muscles that power modern construction and mining. Their health is directly tied to the machine's productivity, safety, and operational cost. Recognizing the early warning signs of failure—be it a subtle weep of oil, a faint hiss, a loss of speed, a shudder in the controls, or a slow downward drift—is not merely a technical skill but a fundamental aspect of responsible and profitable machine ownership. Each symptom tells a story of internal distress, often pointing to issues of contamination, wear, or damage that, if left unaddressed, will invariably lead to greater expense and longer periods of downtime.

A proactive approach, rooted in diligent daily inspections, disciplined fluid management, and a commitment to using high-quality components for repair and replacement, transforms maintenance from a reactive expense into a strategic investment. This is particularly true for the often-underappreciated track adjuster cylinder, whose integrity is the linchpin for the entire undercarriage system, protecting valuable assets like the track roller and front idler from premature failure. By understanding the intricate workings of these powerful components and committing to their care, operators and fleet managers can ensure their excavators perform reliably and efficiently, delivering maximum value in the world's most demanding work environments.

References

Automation Distribution. (2024, September 26). The ultimate guide to hydraulic cylinders: Invention, types, sizing, and applications.

Harvard Filtration. (2023, October 2). Comprehensive guide to hydraulic cylinders. https://www.harvardfiltration.com/guide-to-hydraulic-cylinders/

Hercules OEM. (2025). Hydraulic cylinders 101: Everything you need to know. https://herculesus.com/page.php?name=Hydraulic-Cylinders-101-Everything-You-Need-to-Know&id=523&news_id=152

Hidroman.com.tr. (2025). How does a hydraulic cylinder work?https://www.hidroman.com.tr/icerik/how-does-a-hydraulic-cylinder-work?dil=en

Hidroman.com.tr. (2025). The ultimate guide to hydraulic cylinders. https://www.hidroman.com.tr/icerik/the-ultimate-guide-to-hydraulic-cylinders?dil=en

Hidroman.com.tr. (2025). What is a hydraulic cylinder? How does it work?https://www.hidroman.com.tr/icerik/what-is-a-hydraulic-cylinder-how-does-it-work?dil=en

Zeus Hydratech Ltd. (2025). A comprehensive guide to hydraulic cylinders. https://www.zeushydratech.com/knowledge-base/hydraulic-systems/guide-to-hydraulic-cylinders/

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