Today's trucks call for more durable starters. That means starters that offer fleets higher duty cycles and can operate in a hotter environment, as well as in a range of colder temperatures, and can do so without the use of starting aids.

Another trend in the industry is the move toward gear-reduced starters for increased power. Russell Ford, president and CEO of Prestolite Electric, says gear reduction technology, with origins in the aerospace industry, is now finding its place in medium and heavy-duty truck applications. “Gear-reduced starters apply mechanical leveraging to produce the same amount of output to crank an engine as direct-drive starters, but with a smaller, less expensive motor. They are also inherently more durable by design than direct-drive models.”

According to Ford, Prestolite started moving towards gear-reduced starters two years ago. “We now have an entire range of designs to cover everything from 70mm to 125mm starters with outputs from 3 kW to 8 kW in a 12-volt model.” The starters are designed to provide in excess of 40,000 start-stop cycles before failure. They also allow fleet operators to start their engines unaided in extended temperature ranges.

Tim Barnes, product manager for Delco Remy Heavy Duty Systems division of Remy Inc., says stricter emissions standards that are necessitating changes to various diesel engine platforms mean less packaging space under the hood for starters, which also have to operate in higher temperatures and require 10 to 20% more cranking speed and power. “All of this must be accomplished while improving durability of the units beyond what has traditionally been acceptable,” he points out.

In order to meet fleet demands for starters that reduce the risk of failure, more efficient designs and innovative manufacturing methods are required, says Barnes. “With the high cost of fuel, any changes to reduce starter mass while improving cranking demands, such as the transition from straight drive starters to planetary gear starters, are beneficial in terms of fuel economy.”

Barnes states that Delco Remy planetary gear starters have robust drivetrain designs, like the 39MT Gen III drive system, which makes them more resistant to high impact loads and 40% stronger than the previous generation. OCP (Over Crank Protection), designed to reduce starter failure due to thermal damage from over-cranking, is also available as an option on most Delco Remy models.

Dave Stone, executive director, heavy-duty, Mitsubishi Electric Automotive America (MEAA), says an emphasis on reducing downtime has led to fleets demanding that their starters last beyond the trade cycle of their vehicle. “New anti-idling legislation is increasing the frequency of starts that a truck will see during its lifetime. We've taken a proactive approach to developing starters to meet the requirements of a high start-cycle environment from the beginning.”

According to Stone, technologies such as electric soft-start; oversized, sealed ball bearings; and advanced dust and debris sealing have contributed to MEAA's success in the North American marketplace. Combined with MEAA's automated assembly process, he says, these technologies have enabled the company to produce starters with a failure rate of less than 1%.

“There is always a push to drive out complexity and potential sources of failure whenever possible,” Stone asserts. “Through improved motor design, MEAA has been able to engineer out a common weakness that required the addition of OCP. By reducing wiring complexity on the vehicle side, we are eliminating another potential source of failure.”

Last year, Denso Sales of California introduced several new starter products, including the PA 90S, a medium-duty planetary gear reduction starter, as well as three new R5.0 heavy-duty starters for Volvo-, Cummins- and Detroit Diesel-powered trucks. Both PA 90S and R5.0 starters are lightweight and feature high torque for maximum power and cold starting ability.

Bosch, which produces new and remanufactured starters for most conventional light and medium-duty trucks, also has full coverage for all Sprinter vans. Fred Padgett, Bosch group product manager, starter and charging systems, says the company's remanufactured starters include many new and remachined components, and all assemblies are thoroughly tested to ensure strength and durability.