Solutions Current Issues > Jan.Feb.Mar_2010 > Tech Session
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HEAVY TRUCK APPLICATIONS
At the intersection of higher standards and lower costs: RL Hudson.
In this Tech Session, we'll be talking about the heavy-duty trucks and buses that are used on the world's highways, and must therefore meet challenging safety, emissions, and cost-of-operation standards over an extended period of service.
For today’s heavy trucks and buses, a service life of a million miles or more is no longer unusual. And this means that every component, such as the rubber and plastic parts and assemblies supplied by RL Hudson, must be designed and manufactured with long service in mind.
Let’s put a million miles in perspective. With commuting, errands, and travel, many family cars accumulate 25,000 miles per year. At that rate, it would take forty years to cover a million miles. Add heavy loads, high speeds, high operating temperatures, extended idling, and the need for high reliability, and you have conditions that will challenge the best designs and materials.
After performance, the next important factor is cost. The cost of a part is not just purchase price, but the total cost, which includes the cost of purchase, installation, service life, and replacement — and includes the cost of premature failure.
At RL Hudson, we understand total cost and its impact on profitability. That’s why our design engineers are involved from the very beginning, effectively becoming an extension of our customers’ engineering departments, sharing and exchanging information while continually providing a fresh outside perspective.
Let’s look at the kinds of heavy truck components RL Hudson is capable of supplying. We’ll ask the question: What advantages do these parts, and others like them, bring to the manufacturer of heavy trucks?
The Lubrication System There are a number of components in the lubrication system that RL Hudson’s design engineers have successfully redesigned, resulting in considerable savings and enhanced performance for our customers.
An early project was a plastic oil fill tube for an engine manufacturer. The original oil fill tube was metal, and the customer was not satisfied with the part’s performance. RL Hudson engineers suggested replacing the old metal part with one that would use a high-strength engineering plastic material. During the redesign process, RL Hudson engineers collaborated with the customer’s designers to create a completely new design that dramatically enhanced the function and appearance of the part.
A related project was a pick-up tube located in the engine’s oil pan. Once again, the existing component was made of metal. Many such assemblies have gasketed connections that rely on numerous bolts to effect a seal. RL Hudson engineers were able to design a plastic system that uses a radial seal which requires no bolts, can use standard O-rings, and is easier to tool. In addition, it saves weight, which is important even in heavy trucks.
The Air Intake System The air intake system of a heavy truck engine is complex, and it must provide an adequate volume of very clean air for — as we have seen—perhaps a million miles or more. At RL Hudson we design, engineer, and supply a number of air intake system components that yield higher performance and lower cost. One example is a throttle coupling that uses molded rubber and plastic to combine multiple components into one, eliminating potentially service-intensive joints. Installation is simplified, service is reduced, and as with the oil tube designs, meaningful weight reduction is achieved.
Design Considerations There are two important design and engineering- related aspects of this discussion. First, to obtain the greatest benefit when converting a component or assembly from metal to plastic (or to a combination of plastic and rubber), the conversion should be approached as a system, not as simply replacing a metal part with a plastic part; and second, that such a conversion requires a high level of design, engineering, and testing capability. As we’ve mentioned, when you take advantage of this capability from the earliest concept and design stages of a project, you maximize the benefit of the new design while minimizing time and cost.
This is especially true when a component or system is subject to US and European emissions or safety standards. These standards continually evolve, usually becoming stricter, and staying current with them, and even anticipating them, is key to a successful design.
And what about hoses, caps, gaskets, seals, covers, and the many plastic and rubber parts that are used, or could be used, in heavy truck applications? Do they have special requirements? Yes, certainly. The expected service life of heavy truck components, as reflected in product testing, is as much as five times that of passenger vehicles.
One way to illustrate this difference is creep testing. When a plastic part is put under sufficient load in the presence of heat, oil, water, or a combination of these environmental factors, it may deform permanently. A maximum amount of deformation is permitted over the span of the test. Automotive creep requirements are typically 1,000 hours, while heavy truck components must often be tested to 5,000 hours. Similar requirements extend to rubber components, which must pass extended compression set and/or tension set testing.
Let's return to cost for a minute. It's no secret that enhanced performance and service life can cost more, primarily because premium materials are more expensive. Fluoropolymers and fluoroplastics, chlorosulfonated polyethylene, polysulfone—these familiar engineering materials are well-known to RL Hudson's design engineers. Sometimes they're the best choice, but with RL Hudson's materials testing capabilities and depth of materials knowledge, coupled with a systems approach, you won't be faced with purchasing a part made with a more costly material when a less costly material, used in an optimized design, will provide the same service.
It looks like I'm about out of time, but here's a final thought: one of the defining characteristics of the heavy truck industry is its interlocking relationships between truck makers and engine makers, and its oftencomplex supply chains, with engines, drivetrains, brakes, and other systems being manufactured in plants all over the world. As an international company, RL Hudson understands what it takes to design and manufacture not just parts, but (to borrow a familiar phrase) to provide integrated solutions to the challenges faced by today's heavy truck industry.
