Launch Assist

April 18th 2005

It is interesting how the perceived cost of new technology, and resitance (for whatever reason) to adopt new technology seems to create a situation where it is literally years before some types oftechnology really go mainstream.

Many years ago as a professional truck driver I worked with 5x4 manual transmissions. 10, 11, 13 and 18-speed manual transmissions. Then, on a number of occasions I got to drive a Freightliner (in l985-86) pulling a set of Rocky Mountain doubles that was equipped with an Allison Automatic Transmission.

Alter driving that truck with that automatic transmission I thought for sure that in the future every commercial vehicle would be equipped with an automatic transmission. Boy was I wrong!

Now, let's fast forward to a group called the Hybrid Truck User's Forum that held its 2004 national meeting on October 14, 2004 in Kalamazoo, Michigan.

Steve Nash, director of new business ventures for Eaton Corporation, introduced the Hydraulic Launch Assist (HLA) System which was installed on a Peterbilt 320 Refuse Chassis bailasted to 65,000 lb. GVW with a CAT C-l0 315 hp Diesel Engine and Allison 4560 5-speed transmission.

This system, also called a "Parallel Hybrid Hydraulic" regenerative braking system works to recover energy normally wasted as heat during braking and uses it to supplement the engine's power during acceleration.

As with most hybrids there is that "sweet spot" of applications and the greatest benefit of HLA is realized for vehicles with heavy start-and-stop cycles such as refuse vehicles, city transit or shuttle buses and pick—up and delivery vehicles.

Initial testing with a baseline of non-HLA versus a vehicle equipped with HLA had very impressive results. Testing was accomplished in two different modes: an Economy Mode where performance was held constant to maximize fuel economy benefits and a Performance Mode in which there was an attempt to strike the best balance of improved acceleration with improved fuel economy.

In the Economy Mode there was a 28 percent improvement in fuel economy averaged over a statistically significant number of trial test runs and a 5l percent improvement in brake energy savings.

In the Performance Mode there was a 17 percent improvement in fuel economy (the lower figure was expected) a 26 percent improvement in vehicle acceleration resulting in a stop-to-stop time improvement of 11.5 percent and a 51 percent improvement in brake energy savings equal to that of the Economy Mode.

Unfortunately I have not had the pleasure of driving a vehicle equipped with this system.

However, my editor, Mark O'Connell, had the opportunity to do just that at the Eaton Proving Grounds this past February. According to Mark "these things take off like slingshots" in the Performance Mode which should bc music to the ears of all those in the refuse industry who are constantly trying to improve productivity (Cycle Time Improvement).

For you refuse or transit bus safety people please do not panic, for safety the HLA system is by-passed in a panic stop situation immediately activating the antilock braking system.

Now, for those individuals who are the consummate "Bottom Line" decision makers in the fleet industry here is something to think about.

According to Nash, Eaton "did a good bit of research on the subject of your business, looking at average revenue per stop, operating cost for drivers and trucks, overhead, depreciation, driving cycle, maintenance, as well as average cost per drop at the local landfill. We factored in the improvements HLA can provide based on all those factors'..and with some assumptions of final installed cost to the end user; we conclude that the Eaton HLA system installed in a Peterbilt 320 chassis can create an operating revenue payback within 2 to 3 years."

Interest in the system has been so great that Eaton, Peterbilt and the Texas Commission for Environmental Quality (TCEQ) have fomted a partnership (with grant money provided) to Drive Hybrid Success in the refuse market.

However, as with all new technologies there is still work to be done before it reaches production. Production intent design and validation work is scheduled for completion in 2005, and production plans are for 2007 or 2008.