In part one of this overview we discussed the history of hydraulic pump repairing, rebuilding and remanufacturing and the factors fueling the growth of the industry. The material was abstracted from an article written by P.K. Guha in Hydraulics & Pneumatics magazine.1

In this second and final blog in this series we will discuss Guha’s three categories of hydraulic products; the differences between repair, rebuilding and remanufacturing; and the role of aftermarket parts in the hydraulic products service industry.

Hydraulic product repair is complex.

To simplify understanding of the different methods of repair, Guha divides hydraulic products into three categories — dynamic, intermittent-dynamic and static — and provides a description of each.

Dynamic, as the name implies, encompasses hydraulic products that call for continuous motion, including at idle speed when not at load condition. Because of this continuous motion, wear and tear is a natural occurrence in the mating components, even within a hydraulic product’s lifespan. That is why pumps are one of the hydraulic product components that fail most frequently within and beyond the designed life span.

Intermittent-dynamic hydraulic units are those that generally don’t run all the time. These include hydraulic motors, directional valves and servo proportional valves. Because they aren’t in continuous motion the natural failure rates for these components are less that the failure rates for hydraulic pumps.

Static hydraulic products are “open-close” type of components. The natural wear on these products is much less than dynamic or intermittent-dynamic components so their life expectancy is much longer. Static hydraulic products include pressure, flow, sequence and check valves, and inserts.

These categories are important because the category of the hydraulic component helps determine the type of service required — repair, rebuild or remanufacturing. A repair returns an old, failed component close to its original shape and size and ensures that it functions like the original component. If the repair can’t provide the full and desired function of the original, the component should not be repaired.

Pumps, motors, valves, controls and their parts generally can be repaired as long as the component dimensions, tolerances and clearances are within the prescribed limits. In the rebuild process the failed product is dismantled and the reason(s) for the product failure are identified. The unit is built again with either new or remanufactured parts.

If a hydraulic pump or motor is rebuilt with new components or parts it doesn’t mean that it is a “repaired unit” as it must go through the dynamic testing process to ensure that the rebuilt unit has the same engineering specifications as a new one. Remanufacturing functions can be divided into two areas – manufacturing on the existing core and “improved engineered.”

In the first instance the existing core is restored to near acceptable originality through lapping, grinding, turning and other engineering processes. Care is taken to make sure that the original dimensions are not distorted, and the material composition remains the same.

In the second instance, reengineered components are often brand new and considered “improved engineered” or “reverse engineered.” Tolerances and clearances in mating areas are often tightened when reverse engineered to improve efficiency and performance.

Improved engineered products are not “aftermarket” products. “Aftermarket is a market opportunity, not a product description. For example, if 10 injection molding machines with 2 hydraulic pumps each were sold in 2006, by 2008 these 10 machines could have generated a market potential for 20 pumps to be repaired, rebuilt or replaced. This market potential is known as the “aftermarket.” Other terms loosely used for these situations are “look-alike” and “will-fit.”

When original manufacturers cease to make products, others reproduce them, often to the original specifications and function of the original manufacturer’s product. These “look-alike” and “will-fit” products will have branded names and are usually less expensive and more readily available than the originals. Providing a quality product that reduces downtime and increases productivity is a cost-saving “win-win” situation for both the manufacturer and the consumer.

Servo Kinetics is a full-service hydraulic repair, inspection and rebuild facility that delivers the highest quality standards at the lowest possible cost. We’ve been in business for over 45 years and have worked with industries that have very exacting standards and include some of the most tech savvy companies in the world.

Our services include Vickers classic factory rebuilds, Beach Russ repair, hydraulic field piping services and much more. We also provide reverse engineering services and manufacture new pumps and motors. Call us to learn more about our services and ask about our Special Offers!


3 Understanding the Hydraulic Repair, Rebuild and Remanufacturing Industry, P.K. Guha, 4/8/2009