Multifunctional gasket simplifies hydraulic pitch system


Energy / wind power

By rethinking the existing design of an oil tank, the idea for a completely new molded gasket is born. The design becomes simpler and the quality of the entire hydraulic system is significantly improved.



Pitch system

Oil tank

Rotor name (Hub)

Wind turbine

The challenge

The case concerns an oil tank for a hydraulic control system in wind turbines: a square, welded steel tank with a lid on which hydraulic pumps etc. are mounted. It's basically a well-functioning design, but the manufacturing process is too laborious. For example, a steel channel must be welded onto the tank to collect waste oil, which is both expensive and impractical. Leaks and deformation of the relatively large gasket occur because it is difficult to achieve the correct tightening of the tank lid. So PMC wants the design optimized in two areas: Create a tight and stable connection between oil tank and lid. And devise a production-efficient solution for collecting the inevitable waste oil.

The solution

The first part of the task is solved by embedding flat metal disks that are 20 percent thinner than the rubber in the gasket. This ensures the exact compression that is optimal for the application. 

The second part of the task is accomplished by integrating the oil collection into the shape of the rubber gasket: Placed under the lid, the gasket acts as a "gutter" and directs the oil safely to a collection container or recycling. 

The choice of sealing material is a challenge in itself and a contributing factor to leaks. From the inside, the application is exposed to an oil mist. From the outside, a mixture of atmospheric oxygen and ozone from a generator breaks down. Common rubber types have difficulty withstanding both of these media. 

The solution is to switch to an AEM compound - a rubber compound that excellently combines the properties of NBR rubber (optimal for oil vapor) and EPDM (particularly well suited to withstand outdoor climates and atmospheric influences).

Added value for the customer

The installer no longer has to manually measure and check torques on the lid tightening bolts, as the molded-in spacers control the compression. The risk of leaks is eliminated - and as a bonus, installation work is faster.

The tank construction has become simpler as PMC eliminates the difficult welding of a steel channel around all four sides. PMC Group significantly increases the value of the product - without adding a single penny to the total unit cost.

Clearly better quality at no extra cost...

" The gasket has really proven its strength with built-in torque protection, easy installation and long durability - and the integrated function that diverts waste oil to a closed plastic container makes the solution more than just a good gasket. 
Custom development sounds expensive, but the total production cost per system unit is actually unchanged - so the significantly improved quality is a plus for both the product and the customer's business.

Cases from different industries and applications

We always aim to create added value for our customers. This happens with one or more creations that improve your product, machine or plant - and perhaps enable a new, innovative idea? 

See selected case studies with examples of product solutions that show how Betech is practicing the mission, Improving your productsin a wide variety of applications and industries.


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