Fluid Power

Date: 30.10.18
Two new products join the range of hydraulic seals incorporating lubrication management principles to meet the requirements of demanding applications.-By Jan Sklucki

MILLIONS OF HYDRAULIC SYSTEMS ACROSS THE WORLD keep passenger vehicles, excavators and aircraft functioning every day. Equipment like this wouldn’t be possible without hydraulic systems that multiply force safely, efficiently and reliably.

As would be expected: as the applications become more advanced, so do the hydraulic systems required to support them.

Incorporating lubrication management principles

Newer systems are being designed to be smaller and lighter, but this leads to elevated pressures and speeds during operation, putting more and more strain on seals and increasing wear and friction. “Materials like polyurethane are reaching their performance limits in some applications,” says Alberto Livi, Product Manager for polyurethane seals at Trelleborg Sealing Solutions. “Which is where lubrication management can be applied to the whole sealing system to improve performance.”

Lubrication management examines the whole system and looks for areas where seals can work as a team to better achieve the overall objective. “The fluids within the system are often seen as a challenge to seal against or withstand, but they can equally be viewed as supporting team members,” explains Alberto.

For example, a secondary seal is often used to provide redundancy to a system or to further improve sealing characteristics. In particular, heavy-duty applications require a sealing system solution, rather than an individual product, to ensure long service life and leak-free performance.

Watch the film the film to learn more

Systems working together

“As the primary seal within the system becomes more effective, the secondary seal is running without lubrication. By allowing a small amount of lubricating media through, the secondary seal isn’t suffering the same amount of wear normally associated with dry-running conditions,” says Alberto. “By looking at the whole system, the load on each element can be reduced, optimizing friction-wear-lifetime.”

Research and development teams across Trelleborg Sealing Solutions have been working to develop new seals, which incorporate lubrication management principles to deliver optimized performance for today’s modern applications environments. Zurcon® Buffer Seal and Zurcon® Rimseal IM are two of the latest to be launched.

Zurcon® Buffer Seal

Zurcon® Buffer Seal has been optimized to operate as a primary rod seal for heavy-duty applications, such as lift trucks and earthmoving equipment.

Tests show that using a Buffer Seal manufactured from Zurcon® polyurethane with wear inhibitor and partner lubrication reduced compression set behavior and friction by almost 50%. By considering lubrication management, it has significantly improved performance and wear resistance in the secondary seal.

The seal has a number of innovative features to increase performance. It uses a combination of materials to extend the service life. The main sealing lip is manufactured from Zurcon® material, but is accompanied by a solid antiextrusion ring made from a hard thermoplastic. In addition to this, it incorporates radial slots and channels to avoid blow-by effects and a dynamic lip design to minimize friction and ensure back-pumping.

The shape of the lip guarantees optimal pressure distribution across the seal and constant lubrication. When un-pressurized, slots within the seal ensure that blow-by cannot occur. When pressurized, a relief mechanism kicks in to level pressure and ensure adequate lubrication of the whole rod.

“These kind of designs feature a lot of technology and are backed-up by finite element analysis and field testing, so both theoretical and empirical proof,” says Alberto.

Zurcon® Rimseal IM

The result of continuous development in the form of material and design improvements, the Zurcon® Rimseal IM is an O-Ring energized seal profile that comes as a result of continuous development of sealing systems with lubrication management principles in mind.

The design and material of Zurcon® Rimseal IM are optimized to take advantage of tandem seal teamwork. By deeply studying the contact pressure distribution and its variations performance has been optimized, particularly with respect to sealing ability and friction.

Zurcon® Z13 was chosen due to its mix of favorable physical-mechanical characteristics and chemical resistance.

“Zurcon® Z13 was an excellent choice of material to start with for the next generation of seals. It allows injection molding or lathing, keeping the pricing competitive.

When this seal is combined with lubrication management, the friction reduction is even more significant for the whole system,” finishes Alberto.

Download catalog