Choosing the right seal for your hydraulic cylinder
The seals of a hydraulic cylinder play a crucial role in its operation.
Their purpose is to seal the cylinder so that the oil remains inside. The piston seal specifically prevents oil from passing from one chamber to another past the piston.
Oil is pumped into the cylinder at high pressure using a hydraulic pump, which causes the piston to move. This generates the force required for the cylinder’s motion.
If a hydraulic cylinder lowers by itself, there may be an issue with the pressure, and the seals may be leaking or improperly installed. If this happens, it’s worth replacing the hydraulic cylinder’s seals. After that, it’s essential to ensure that the new seals are installed with care.
Choosing the right seal extends service life
Selecting the correct hydraulic cylinder seal significantly extends the cylinder’s lifespan. In most cases, the equipment manufacturer selects the seals for the cylinder. The choice is based on the operating environment, movement speed, and the system’s pressure level.
For example, if very high movement speeds are required, a Teflon seal suited specifically for that purpose is selected. However, it’s important to also consider the potential downsides of such seals—Teflon seals are less resistant to impurities and are more prone to scratching. Scratches, in turn, can lead to leaks.
Choosing the wrong type of seal can cause the following issues:
Damage: If the seals are used in unsuitable conditions, they may become brittle, start to leak, or crack.
Safety risks: If the seals break or degrade, the cylinder could fail during lifting, posing a serious safety hazard.
Reduced efficiency: The wrong seals can slow down operation and reduce overall efficiency.
Higher long-term costs: Inefficient operation and frequent seal failures lead to more major maintenance needs over time, increasing costs.
Different Types of Seals and Their Intended Use
As mentioned, engineers experienced in hydraulic cylinder design select seals based on their specific application. If a seal is damaged and needs to be replaced, it’s best to stick with the model originally selected by an expert—this isn’t the time to experiment. Below, we outline the most common types of seals
Teflon Seal
A Teflon seal enables high movement speeds thanks to its low friction. Because of this, it descends smoothly, making it particularly suitable for forklifts. Teflon seals are commonly used in the boom cylinders of forestry machines for moving, loading, and transporting logs. The downside of Teflon seals is that they are more sensitive to scratches and contamination. They are also expensive and difficult to install.
Compact Seal
A compact seal is made from a combination of plastic and rubber. It resists contamination well and is cost-effective. Compact seals are also easy to install. They are used in conveyor lines for moving logs, in various process industry tasks, and in work machines that don’t require high-speed movement.
Packing Seal
Packing seals are used in older model excavators. They have multiple sealing lips in a row. Packing seals tolerate scratches and rough handling well. They are particularly suited for lifting and moving heavy loads. The downside is that they are expensive.
Polyurethane Seal
Polyurethane seals withstand pressure and temperature well and are not sensitive to contamination. They are the most common type of seal for rod sealing, and there are many different profile options. Turned seals are often made of polyurethane, and availability is good. PU seals are by far the easiest and most hassle-free to install.
