Compact transmission reduces consumption by up to 40 percent

Dana Rexroth Transmission Systems, a 50-50 joint venture of Dana Incorporated and Bosch Rexroth AG, presents a compact variant of its award-winning HVT for forestry machines and fork-lift trucks based on proven designs used in material-handling applications.

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Dana Rexroth Transmission Systems now also offers the advantages of hydromechanical variable power-split transmissions (HVT) with reduced dimensions for forestry machines and fork-lift trucks. At Agritechnica, the company presented an especially compact design with the HVT R2 Short Drop. It is based on series components that have already been proven in other vehicles.The power-split transmission reduces fuel consumption and emissions of mobile working machines by up to 40 percent with improved drive properties across the entire speed spectrum.

Hydrostatic-mechanical variable power-split transmissions (HVT) combine the positive properties of a mechanical drive with those of a hydrostatic travel drive. Originally developed for wheeled loaders and similar vehicles, manufacturers of forestry machines and fork lift trucks increasingly also want to implement this technology to reduce fuel consumption. However, these applications only offer a smaller amount of installation space for transmissions. Therefore, Dana Rexroth has adjusted the arrangement of validated components and redesigned the transmission housing for the new HVT R2 Short Drop (SD) variant. This results in an installation height 100 mm lower than the standard version. Also new is the HVT R2, series 20 variant. It increases the permissible diesel engine power to up to 235 kW. HVT transmissions from Dana Rexroth thus represent a further technological breakthrough for very large torque demands.

The improved efficiency of the drivetrain reduces the consumption of vehicles equipped with HVT by up to 40 percent in comparison to standard torque converters. HVT’s from Dana Rexroth are therefore also used in the European Union´ Forwarder 2020 evelopment program. The forestry machine developed there sets new standards in environmental sustainability, performance, efficiency and productivity.

The wide conversion range of the transmission and the synchronous switching allow for decoupling of the rotational speeds of the diesel engine from the travel speed. Depending on the driving resistance and upcoming hydraulic power requirements, manufacturers can optimize the diesel engine and transmission to the best operating point. This improves efficiency and reduces noise emissions. The hydrostatic braking function limits brake wear and further reduces fuel consumption. HVT improves drive properties across the entire application spectrum. At very low travel speeds, equipped vehicles can be easily controlled and the drivers achieve a high positioning accuracy. The purely hydrostatic first driving range offers the advantage of practically wear-free, continuous and very dynamic reversing without the need to shift gears.

At higher travel speeds in the second and third driving range, the vehicle utilizes the high efficiency of input-coupled, hydrostatic-mechanical power split technology. Shifting between the driving ranges is carried out without tractive force interruption because of the transmission design in which the multi-disk clutches shift synchronously.