052-12 Lohr, 2012-08-20

Energy-Efficient AWD for Trucks

Hydraulic Traction Assistant (HTA)

The Hydraulic Traction Assistant (HTA) offers all-wheel drive response off-road when needed while adding around 400 kg less weight than conventional solutions. This increases the payload capacity, red

Hydrostatic ancillary drive for commercial vehicles provides more traction off-road when needed

  • Additionally driven axle provides more traction
  • 400 kg weight savings compared with mechanical all-wheel drive reduces fuel consumption increases load capacity and provides greater economy
  • Especially attractive for vehicles which are mainly on-road

All-wheel drive is highly advantageous for commercial vehicles which deliver materials to construction sites, have to travel on softened ground or need to traverse hills and passes in winter. The hydrostatic ancillary drive Hydraulic Traction Assistant (HTA) offers an energy-efficient alternative to traditional all-wheel drive. HTA reduces the system weight by around 400 kg by comparison. The lower weight translates into greater useful load capacity and reduces fuel consumption.

Two hydraulically driven wheel-hub motors increase traction when needed on any axis in the vehicle. On-road the motors run in neutral mode to reduce drag losses to a fuel-saving minimum. Off-road and on difficult terrain the driver uses a toggle switch to activate traction mode, even while driving under load. In traction mode the HTA system provides additional power of around 50 kW and additional torque of up to 6000 Nm per wheel.

In creep speed mode HTA improves maneuverability and provides additional working gears which can be used at low, continuous vehicle speeds. There only the two wheel-hub motors drive the vehicle forward or in reverse; the mechanical gearbox is in a neutral position for this purely hydraulic action.

HTA can be integrated into existing vehicle concepts without any major modifications and does not affect the chassis design, maneuverability or the turning radius, and even provides advantages compared with mechanical AWD.

The HTA Hydraulic Traction Assistant system solution consists of radial piston hydraulic motors integrated into the axle, an axial piston variable pump, a valve block, an electronic controller as well as oil cooler and hydraulic tank. All the components are Rexroth products and have been proven over years in harsh applications on mobile work equipment. Of special interest to the vehicle OEM: as part of the Bosch Group Bosch Rexroth understands and meets the engineering requirements of the automotive sector, especially with respect to functional safety in compliance with ISO 26262. For OEMs this means a significant reduction in the system integration effort required.

HTA can be implemented in 2- or 4-axle vehicles and makes it possible to add the AWD function to vehicle types for which the purchase of a mechanical system would otherwise be prohibitively expensive. This includes especially any vehicle which spends the majority of its time on-road and seldom requires AWD – yet needs to safely and reliably handle difficult terrain when called upon. Such vehicles include tractors and towing vehicles, dumpers, fire trucks, concrete mixers and pumps, skip and bucket loaders, tank and silo trucks, and wood transporters.

Bosch Rexroth AG is one of the world’s leading specialists in the field of drive and control technologies. Under the brand name of Rexroth, the company supplies more than 500,000 customers with tailored solutions for driving, controlling, and moving. Bosch Rexroth is a partner for mobile and machinery applications, engineering, factory automation as well as renewable energies. The company covers the requirements and special needs of each of these markets. As The Drive & Control Company, Bosch Rexroth develops, produces and sells components and systems in more than 80 countries. In 2011, Bosch Rexroth, part of the Bosch Group, achieved sales of around 6.4 billion euros with 38,400 employees.

For more information, please visit

The Bosch Group is a leading global supplier of technology and services. In the areas of automotive and industrial technology, consumer goods, and building technology, over 300,000 associates generated sales of 51.5 billion euros in fiscal 2011. The Bosch Group comprises Robert Bosch GmbH and its around 350 subsidiaries and regional companies in over 60 countries. If its sales and service partners are included, then Bosch is represented in roughly 150 countries. This worldwide development, manufacturing, and sales network is the foundation for further growth. In 2011, Bosch spent approximately 4.2 billion euros on research and development and applied for over 4,100 patents. With all its products and services, Bosch enhances the quality of life by providing solutions which are both innovative and beneficial.

For more information please visit: ,


Search press releases


Susanne Herzlieb
Maria-Theresien-Straße 23
97816 Lohr am Main
Phone: +49 9352 18-1573