Special Trailer Keeps HMMV Highly Mobile

A MANUFACTURER of converter dollies is building more than 5,000 trailers designed to be hauled up mountains, bounce over obstacles, and cross rivers.

Silver Eagle Manufacturing of Portland, Oregon, has begun delivering its High-Mobility Trailer (HMT) designed to be towed behind the Army's High-Mobility Multi-Purpose Wheeled Vehicle (HMMWV). Commonly known as the Hummer, the HMMWV was built to climb 60% grades and to travel transversely along a 40% slope without tipping over. It can ford water as deep as 60", handle the impact of an 8"-radius speed bump, and scale 18" steps.

Significant engineering effort went into producing a light truck that can handle these heavy demands. That is why the Army required a trailer that is at least as mobile as the truck that pulls it.

Because of the G forces to which the trailer is subjected, the HMT has a cargo rating of only 2,800 lb. Even so, the addition of the trailer enables troops to carry twice the cargo as the HMMWV alone. Tare weight of the HMT is 1,400 lb, the result of using aluminum for the cargo box. The drawbar is aluminum, while the surge brakes and axle are steel.

"At first glance, the HMT looks like a simple utility trailer," says Gary Gaussoin, president, "until you recognize what the HMMWV can dish out. It whips a trailer around pretty severely. And since the HMMWV has a limited towing capacity, we had to make the trailer as light as we could to maximize its cargo capacity. Designing this trailer was a lot more challenging than it looks."

Other requirements include the capability of being air-lifted by helicopter, the ability to survive a low-altitude parachute extraction, and a ride that generates no more than 3 Gs when the trailer strikes an 8"-radius speed bump.

Similar Specifications

Because of the performance requirements, the HMT uses the same wheels and tires as the HMMWV to allow the vehicle to travel, even after the tires have lost air. The independent trailing-arm suspension provides the trailer with the same ground clearance (16" loaded) and axle track as the HMMWV.

Free-backing hydraulic surge brakes help the combination stop. The brakes apply automatically in the event of trailer breakaway.

The HMT has a 7-ft cargo box and an 11-ft overall length. The frame is composed of longitudinal and transverse rectangular aluminum tubes secured with high-strength steel rivets. The double-wall body is assembled with both rivets and spotwelds. The only other welding on the body is on the wheelwells and corner caps.

"The Army expects this trailer and the HMMWV to perform on the front lines," Gaussoin says. "They want the trailer to be durable and to provide as much payload as possible. But the big concern is mobility. They don't want the HMMWV to be unable to reach some place just because it has a trailer in the back."

New Manufacturing Plant Silver Eagle converted a beverage warehouse into a 77,000-sq-ft plant to produce the 5,600 high-mobility trailers. The conversion involved significant renovations to the building, including the routing of compressed air throughout the plant and a major upgrade of the electrical system.

The company bought a substantial amount of plant equipment and built hard tooling to provide the level of repeatability required in the contract. Among the purchases: additional CNC press brakes, robotic welders, CNC milling machines that retain dimensional tolerances more closely than punching, and a router table for precision cutting of identical parts from a stack of aluminum sheet.

The biggest capital expense was a $1.4-million automated E-coat system that enables Silver Eagle to meet military coating performance requirements for durability while also complying with EPA regulations. The automated line electrically deposits primer on both steel and aluminum parts.

"E-coating is a mature process in the automotive industry, but it is unusual in trailer manufacturing because it is a costly process and because of the size of the components that are being coated," Gaussoin says. Silver Eagle's E-coat system consists of a series of 10 tanks, each of which measures 10' wide, 7'4" high, and 21/2" deep.

Steel and aluminum components share the same conveyor line, but not all of the same tank. For steel pieces, the process begins with grit blasting to remove scale. Once they have been mechanically cleaned, the steel parts as well as those made of aluminum are hung on a conveyor to start the automated process.

"An electrical charge bonds the coating to the metal," Gaussoin says. "The process is about 96% efficient."

As the part is lifted from the E-coat bath, most of the coating falls directly back into the tank. What little waste that the process generates occurs as the parts move from the E-coat bath through the two rinse baths. Even there, most of the coating is separated from the rinse water and cycled back to the E-coat tank.

Meeting VOC Regulations One of the virtues of the E-coat system is its ability to meet air-quality standards. The coating solution is 85% water and is low in volatile organic compounds.

"It has only .6 pounds of VOCs per gallon," Gaussoin says. "The federal standard is 3.5 lb per gallon."

Baking the coating is a key to reducing cycle times. Parts make the trip through the system-from entering the line until leaving the oven-in about 90 minutes.

Baking also helps reduce the amount of solvents needed-solvents that would evaporate and enter the atmosphere.

"We use heat instead of chemicals to crack the epoxy," Gaussoin says. "Baking helps us keep our VOC emissions low while at the same time speeding flow through the drying area that for some manufacturers tends to be a bottleneck."

Gaussoin also likes the universal coverage that E-coating offers. The coating penetrates even remote areas of the part unless air is trapped as the part is submerged. Silver Eagle addresses this possibility in the way the part is engineered or in how it is suspended from the conveyor line.

Under Control Silver Eagle is using the E-coat process in order to meet demanding military specifications regarding durability of the coating and corrosion resistance of the HMT. As is typically the case with defense contracts, a government inspector has an office at the Silver Eagle plant to make sure that all aspects of the HMT, including the finish, meet specifications.

To meet Silver Eagle and military standards, the E-coat process requires constant monitoring. The company performs more than 40 tests per shift on the various tanks to make sure that the pH and other parameters are within tolerance. This is in addition to constant monitoring the gauges of the equipment to make sure that the temperature is right and the E-coat is constantly churning.

"We pump the E-coat 24 hours a day to make sure that it remains in suspension," Gaussoin says.

A chiller unit makes sure that the temperature of the E-coat does not exceed 80° F. On the surface, that should be relatively undemanding until one considers the massive electrical energy passing through the E-coat tank.

Applying the Camouflage Only the primer can be applied with the E-coat process because the top coat must be applied in a precise camouflage pattern.

Once they leave the bake oven, the steel and aluminum parts are assembled into a complete trailer. They then receive topcoats of Chemical Agent Resistant Coatings (CARC) to produce a non-reflective camouflage finish.

The military has several camouflage schemes. Depending on where it will be used, the HMT may be painted Arctic white, a desert tan, or the familiar green, black, and brown.

"The patterns are very specific," Gaussoin says. "We must be within an inch of the specified pattern. It seems a lot of research goes into determining exactly where the colors are applied so that the visibility of the trailer is minimized for the environment in which it operates."

Testing the Results Results of the painting process are tested at least daily. This includes testing the thickness of the coatings to make sure they meet specifications. Adhesion also is tested by making horizontal and vertical scribes at prescribed intervals. A specific type of tape is then pressed over the scratches. If the paint remains intact after the tape is peeled away, the test is considered successful.

Every six months, Silver Eagle sends a sample of production to an independent test lab for a 1,000-hour salt spray test. This is designed to evaluate the coating's ability to resist corrosion.

PPG, Silver Eagle's paint supplier, also is involved in the testing. The company set up the tests that Silver Eagle personnel use to monitor the variables of the E-coat system. Silver Eagle sends PPG the test results, and PPG in turn supplies Silver Eagle with monthly reports on how the system has performed.

In Pursuit of Business For Silver Eagle, building the HMT is the fruit of a process that began more than a decade ago.

"Our converter dolly business really took off when the Surface Transportation Assistance Act made doubles trailers legal nationwide in 1982," Gaussoin says. "There were several years in the 1980s in which sales doubled annually."

In 1986, Silver Eagle decided to branch out. The company began developing what eventually became the High Mobility Trailer. Over the years, the military's support of the program fluctuated. At times, the future of the HMT looked bleak. Gaussoin gave up on the program after implementation dates kept being postponed and the military's specifications continued to change.

"We became interested in the HMT because we were searching for an area of business that was contracyclical to the converter dolly market," he recalls. "In 1991, we just wanted to sell the design to some other government contractor and move on. It didn't look like the program was going anywhere."

But the Army never gave up on the idea. In 1993, the military again solicited bids for a trailer designed for the HMMWV. This time the proposal became reality.

"When the specifications came out in 1993, they essentially described the trailer that we had been working on all these years. We were ready."

Changing Approach The government is changing some of the ways it deals with defense contractors, Gaussoin says.

"We are relatively new to the business of selling to the government," he points out. "Our approach to the commercial marketplace has been to establish relationships with our customers. One of our largest fleet customers told company employees in its newsletter they should call me personally if they had any questions or problems with the converter dollies we sold them. I got some calls-which is fine. Relationships with our customers are important.

"Government contracts tend to be more adversarial. Fortunately, we were able to put together an agreement with Electrospace Systems (now Raytheon E Systems since being acquired by Raytheon). We are subcontractors. Raytheon buys the materials and handles most of the contacts with TACOM, something that has made it much easier for us. While not brand new to the area of defense contracting, we certainly are not entrenched."

Dolly with a Body When viewed at certain angles, the HMT looks a lot like a converter dolly with a body mounted on it. Not surprisingly, Silver Eagle has been able to combine HMT production with its line of commercial converter dollies.

The plant that Silver Eagle set up for the HMT order is producing an increasingly larger share of total company output. Prior to the opening of the plant, Silver Eagle manufactured its converter dollies in a nearby 36,000-sq-ft facility. Management plans to complete the plant consolidation process by the end of the year.

"The HMT order has required some stringent quality standards," Gaussoin says. "It has required us to purchase automated equipment that would have been extremely difficult for us to justify. But now that we have the equipment and the quality-control procedures in place, the incremental cost is minimal to build our commercial products the same way."

A good example is the E-coat system which provides corrosion protection for both the HMT and commercial converter dollies. A major portion of the company's CNC equipment was acquired because the quality standards of the HMT order required it. Yet with equal ease and little setup time, the same equipment is used to fabricate Silver Eagle dollies.

Trucking Family Silver Eagle is a family business that traces its roots back to 1933 when C Julius "Judy" Gaussoin started a tanker fleet.

In those days, full trailers were popular. When he lost one of his drivers in a rollover accident, Judy Gaussoin decided he could design a better suspension.

Judy Gaussoin developed a variety of products for the truck industry, including transmissions and the split brake system. "He always wanted to do things the best way and the safest way he knew how," Gary says of his father. "Safety was very important. When we were kids, he used to give us safety quizes at the breakfast table."

The trucking company that Judy Gaussoin founded continues today under Ross Gaussoin, Gary's brother and a former chairman of the American Trucking Associations. Silver Eagle Company is a general-commodity LTL carrier serving the Pacific Northwest. The company moved out of petroleum transportation in the 1950s.

The converter dolly is the primary product at Silver Eagle Manufacturing. The company's CST20 has a transversely mounted two-stage leaf spring system, Rockwell TN 4670 5" axle, and 36" fabricated fifthwheel. ABS currently is optional but will be standard when NHTSA's ABS regulation goes into effect in March.

Looking Ahead Meanwhile, Silver Eagle is producing 20 High Mobility Trailers per day. The company is scheduled to complete the current contract in mid-1998.

"There is an option for another year's production that we believe the military will exercise," Gaussoin says.

The company has sold a limited number of HMTs to commercial accounts. This should confirm the suspicions of trailer manufacturers that customers really do drag trailers up mountains and through rivers.

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