Prototype was developed by entsorgung herne in cooperation with Allison Transmission, Bucher Municipal and Daimler
HERNE, Germany – Equipped with a fully automatic Allison transmission, a new road sweeper with a single engine has improved ease of use and efficiency for entsorgung herne, the municipal disposal and cleaning institution in Herne.
Since the end of last year, entsorgung herne has been operating the first large sweeper built on a Daimler ATEGO chassis, equipped with a Bucher body and an Allison 3000 Series™ featuring a single Euro 6 engine. Previously, large chassis-mounted sweepers have mostly relied on a two-engine configuration.
For environmental reasons, the fleet of entsorgung herne had entirely operated on trucks equipped with manual gearboxes. However, there was a desire to take the fleet to a higher level of automaticity to make driving the trucks more comfortable and efficient.
"Constructive limitations, cost and current environmental protection regulations required new sweeper technology," said Werner Hüttemann, technical director for entsorgung herne.
Because there was no single engine sweeper with Euro 6 emission standard available on the market, Hüttemann initiated a collaboration with Bucher Municipal and Daimler. The first pilot project with a Bucher body and a Euro 6 Mercedes ATEGO 1524K chassis equipped with an automated manual transmission failed because of the gearbox. Testing proved that an acceptable trade-off between very low sweeping speed and shift quality was not achievable by using the automated manual solution. At that point, Allison was approached to join the project. The standard ATEGO gearbox was replaced by an Allison 3500 model automatic transmission.
Allison’s patented torque converter, the availability of two engine-driven PTO provisions integral to the transmission housing and the flexibility of advanced electronic controls made the second attempt successful. The two-engine driven PTOs are simply and effectively connected to the cleaning equipment, making it possible to eliminate one of the two combustion engines and its complex exhaust system. Thus, the street cleaning could be done quieter, with less emissions and with a potential for an increased payload.
A significant technical challenge was interfacing the body and transmission to deliver the expected shift quality over an entire range of operating conditions, from sweeping to commuting. In particular, with its greater spread and its deep gear ratio in the first gear, the Allison 3500 model enables the slow driving that is crucial for sweepers.
"The Allison specialists, the team from their German and Swiss distributors, along with the engineers at the Swiss headquarters of Bucher Municipal, mastered this challenge very effectively," said Hüttemann.
Advantages of street cleaning with an Allison fully automatic transmission
While the original project aimed to relieve Herne drivers from the constant burden of the manual-shifting process, the adoption of the Allison fully automatic proved to deliver several additional operational advantages.
According to Hüttemann, heavy shifting and recurrent clutch pedal operation can lead to premature wear of shoulder or hip joint. Such health problems can be prevented by using fully automatic transmissions
According to Hüttemann, heavy
shifting and recurrent clutch pedal operation can lead to premature wear of shoulder or hip joint. Such health problems can be prevented by using fully automatic transmissions.
In addition, Herne is a large city with high traffic density, parked vehicles and narrow roads causing various problems in daily cleaning and sweeping jobs. “Our drivers should have the surroundings constantly under control and they should be able to concentrate on sweeping and not on operating the clutch and shifting," said Hüttemann.
Furthermore, instead of a traditional dry clutch, Allison transmissions use a torque converter which increases engine torque at launch for improved vehicle performance and maneuverability in severe stop-and-go-operation. The converter module also protects the entire driveline from torque shock and vibrations minimizing maintenance and downtime.
“We are really satisfied with the vehicle,” said Hüttemann. “Whereas the prototype was initially just meant to ease drivers operation, now entsorgung herne is planning to gradually replace all of its existing sweepers with single-engine trucks equipped with Allison transmissions.”
The Bucher sweeper, launched at IFAT 2016, has an OM 936 engine that delivers 238 hp (175 kW) at 2200 rpm and 1000 Nm of torque at 1200 – 1600 rpm. Due to the short wheelbase of 3,560 mm, the sweeper is very maneuverable and provides significant advantages for street cleaning in the city. Another advantage of the now available second series is the even shorter possible wheelbase of 3,360 mm. This results in even greater maneuverability in the sweeping area.
Also, from a financial perspective, the purchase of the large single-engine sweeper with an Allison transmission pays off, since the purchase of the vehicle is considerably cheaper than a comparable vehicle with a hydrostatic system. The maintenance requirements and costs are reduced compared to those of manual or automated manual transmissions.