Mobility Solutions

Powerful, and perfect for limited installation space The new Bosch HEF109-L starter motor for commercial vehicles Extended power range for exceptionally large engines

  • Powerful solution for diesel engines of up to 28 liters displacement as well as for stationary gas-powered engines
  • Engineered for mileage of up to 800,000 kilometers or 14,000 operating hours in off-highway applications
  • Adaptable to stringent system requirements
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  • August 21, 2014
  • Mobility Solutions
  • Press releases

press release

Large-volume engines place great demands on starters. At the top end of the power range, Bosch has a new addition to its 24-volt starter motor portfolio: the HEF109-L “large” heavy-duty starter motor for commercial vehicles and off-highway applications. The powerful starter motor generates 18 percent more power than the tried and tested “M” (medium) type starter motor on which it is based, and thus delivers a maximum output of 9.2 kilowatts. This is enough to reliably start engines with up to 28 liters displacement. Ulrich Kirschner, the president of Bosch’s Starter Motors and Generators division, sums up the benefits as follows: “This new high-performance starter motor is an excellent choice for particularly large engines such as construction machinery. These engines were previously very difficult to start with single starter-motor configurations.” This powerful single-starter solution makes a more complex parallel-starter system unnecessary. The technology is designed to achieve a mileage of up to 800,000 kilometers in on-highway use or 14,000 operating hours in off-highway applications.

Compact, robust, and reliable
The design of the HEF109-L with its 6-pole excitation concept is especially compact, making it particularly suitable for applications where installation space in the engine compartment is limited. The high thermal robustness ensures reliable starting of large engines – even at very low ambient temperatures or in long-lasting starting sequences.

Due to the significantly greater service-life requirements associated with commercial vehicles, the engagement itself is designed as a two-stage process in order to limit the wear of the ring gear and pinion: In the first stage, the pinion shaft including the pinion is moved forward cautiously, engaged, and turned slightly. In the second stage, the main current is released and the actual starting sequence takes place.

A mechanical relay integrated in the starter makes a connection to the engine control unit (ECU) easier. Unlike starts by ignition switch, the ECU can automatically control the starting sequence, which keeps emissions low.

For extreme conditions
The HEF109-L can also be upgraded. One example is the special dust protection, available up to IP57 protection class. An additional feature is the isolation of terminal 31. This separate connection to the battery’s minus pole is a feature of special applications such as railroad vehicles or watercraft, where increased safety and protection requirements against moisture and water apply. For maximum flexibility in diverse installation conditions, the starter motor can also be supplied with all common flange geometries, including a rotatable flange.

Parallel starter-motor systems with increased power output
For applications utilizing even larger-displacement engines, Bosch offers parallel starting systems. By setting two or three starter motors of the 109-family in a parallel-system configuration, the output of each individual starter motor can be aggregated. The new HEF109-L also allows the total output of the parallel starter-motor systems to be increased significantly. With a maximum output of almost 28 kilowatts, diesel engines with displacements of up to 84 liters and gas powered engines with displacements of up to 168 liters can be started reliably under normal conditions. Engines of this size are very common in off-highway applications and watercraft. Stationary engines such as generator sets – also need to start quickly and reliably to stabilize the power supply net if there is a power cut. The HEF109-L is an ideal choice for these applications as well.

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First and foremost, the Bosch stand (Hall 17, Stand B12) at the 65th IAA Commercial Vehicles in Hannover is about efficiency. We are using smart solutions to make conventional commercial-vehicle powertrains not only cleaner, but also increasingly economical. And with technologies for alternative powertrains and fuels, Bosch has the future clearly in its sights. In addition, we show how in-vehicle and internet connectivity can help simplify logistics and make truck use even more efficient.

Mobility Solutions is the largest Bosch Group business sector. In 2015, its sales came to 41.7 billion euros, or 59 percent of total group sales. This makes the Bosch Group one of the leading automotive suppliers. The Mobility Solutions business sector combines the group’s expertise in three mobility domains – automation, electrification, and connectivity – and offers its customers integrated mobility solutions. Its main areas of activity are injection technology and powertrain peripherals for internal-combustion engines, diverse solutions for powertrain electrification, vehicle safety systems, driver-assistance and automated functions, technology for user-friendly infotainment as well as vehicle-to-vehicle and vehicle-to-infrastructure communication, repair-shop concepts, and technology and services for the automotive aftermarket. Bosch is synonymous with important automotive innovations, such as electronic engine management, the ESP anti-skid system, and common-rail diesel technology.

The Bosch Group is a leading global supplier of technology and services. It employs roughly 375,000 associates worldwide (as of December 31, 2015). The company generated sales of 70.6 billion euros in 2015. Its operations are divided into four business sectors: Mobility Solutions, Industrial Technology, Consumer Goods, and Energy and Building Technology. The Bosch Group comprises Robert Bosch GmbH and its roughly 440 subsidiaries and regional companies in some 60 countries. Including sales and service partners, Bosch’s global manufacturing and sales network covers some 150 countries. The basis for the company’s future growth is its innovative strength. Bosch employs 55,800 associates in research and development at 118 locations across the globe. The Bosch Group’s strategic objective is to deliver innovations for a connected life. Bosch improves quality of life worldwide with products and services that are innovative and spark enthusiasm. In short, Bosch creates technology that is “Invented for life.”

Further information is available online at and,

PI8672 - August 21, 2014

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