Tier II emission requirements have been a challenge for all manufacturers of off-highway equipment. However, they posed a special challenge for compaction equipment manufacturers, who faced tight space constraints, an extremely price-sensitive market and increased noise concerns.
Over the last two years, compaction equipment designers had to wrestle with some fundamental choices when it came to bringing their products into compliance. And they didn't have much time to do it. "Unless you make your own engines, you are at the mercy of the engine manufacturers," says Steve Wilson, manager, marketing services and product manager for Compaction America.
One early problem was the availability of prototype engines. "That was critical because you build everything around the engine and we couldn't get the parts fast enough," says Dale Starry, manager of training and applications at Ingersoll-Rand's Road Development Group.
There was also some loss of available horsepower options — especially in the 100-hp range — as engine manufacturers opted to stop production on some lines in order to meet Tier II standards for their other products. That meant many equipment manufacturers had to utilize Tier II phase-in allowances, which permitted them to produce some non-compliant equipment as long as the majority of their machines met the emission standards.
The basic choices confronting manufacturers of compaction equipment were selecting a smaller but "cleaner" engine; adding an aftercooler to lower the temperature of the turbocharged air entering the engine; or adding electronic controls.
Some elected to use slightly smaller engines, but that carries marketing consequences. "In North America, contractors like performance, and it is considered a negative to take performance down," says Wilson.
Adding an aftercooler presented space challenges. "There's not a lot of room in the engine bay area and you're already dealing with additional heat rejection from the Tier II engines," Wilson explains.
Most manufacturers increased the size of the radiators to address the heat rejection issue. This made it much more difficult to add another cooling unit in the limited engine compartment. "It is like stuffing six pounds of sugar into a five-pound bag," says Starry.
The added cooling requirements also presented noise challenges. Europe already has specific noise emission regulations, and OSHA has been cracking down, as well. "Noise is and will be a bigger jobsite issue in the future," says Terry Sharp, manager, solutions and services, Caterpillar Global Paving. Caterpillar is already providing low-noise, variable fan speed, ATAAC cooling systems in advance of any specific regulations.
Other manufacturers have been concerned with increasing the size of the cooling fan. Some switched to quieter, hydraulically driven fans; others changed muffler systems.
Electronics vs. aftercoolers
Choosing whether to go with electronics or charge-air cooling was not an easy task. "You have to juggle complexity, cost and tight packaging," says Starry. "The choice is between electronics, which are more costly but take up less space, and charge-air cooling, which is less expensive but creates packaging problems."
The price differential for electronics is significant, adding as much as 25 percent to the cost of the engine. Compaction equipment manufacturers with their own engine lines have been able to minimize this price impact.
"Since Caterpillar makes its own engines, we have the advantage of a long-term commitment to emissions compliance, while spreading the cost over a wide range of products," says Sharp. "This also helps provide both electronic engines and advanced cooling systems as an integrated package for compaction products."
Manufacturers relying on outside engine suppliers, however, have been forced to absorb the added cost electronics bring. Electronics can also impact other equipment issues since they require the use of gold connectors and new electrical harnesses.