Linde celebrates 50 years of hydrostatic drive

The first Linde truck with hydrostatic drive was unveiled to the public 50 years ago at the 1960 Hanover trade fair.

No-one knew that the truck, designated Hubtrac H3K, would lay the foundation of a success story that continues right up to this day, making Linde Material Handling the leading manufacturer of counterbalance forklift trucks in Europe.

Hydrostatic drive is at the heart of every Linde engine truck up to 18 tons lifting capacity. It is the source of the trucks' sensitive, precise driving and lifting characteristics, as well as their productivity, outstanding fuel economy and reduced maintenance overhead. Even though the principle behind hydrostatic drive has not changed over the years, time and again the development engineers at Linde MH have made crucial technical improvements.With the introduction of the fourth generation of the Linde hydrostatic system, the forklift truck manufacturer is asserting its position as the technological leader with a new generation of transmission offering improved productivity and lower fuel consumption.

Theodor Maurer, Chairman of the Management Board of Linde Material Handling, says: "At Linde, existing knowledge and experience has always been regarded as the starting point in the quest for further development of transmissions and lifting hydraulics. The best example of this is the development of the drive axle: this new generation features two low-speed hydraulic motors, integrated into a compact drive axle, powering the drive wheels directly without the need for speed reduction gears.

Previously, the hydraulic motors operated at 3500rpm requiring reduction gears between motors and wheels, but today's low speed motors operate at just 170rpm so reduction gears are no longer required reducing noise, fuel consumption and emissions.

Progress of this kind requires a deep understanding of the whole system, something Linde has developed in the most effective way possible — through combining truck development and drive technology under one roof. This means that our customers can be confident that by choosing the Linde brand they will be buying into technology that is not only cutting-edge and extremely costeffective today, but also subject to continuous development and improvement for the future."

Taking responsibility for every component As Bernward Welschof, head of the drive technology development at Linde MH, comments: "The essential factor behind every major development stage has been that the drive engineers at Linde MH are able to 'drill down', so to speak, into the truck itself.

This is because Linde is one of the few manufacturers of forklift trucks to take responsibility for each and every component of the truck — from the accelerator pedal through to the wheels.

Furthermore, it is not only the hydrostatic drive unit that benefits from the joint development of hydraulics and trucks under the same roof; the complete lift hydraulics system, including its electronics and control levers, and the power steering, are also products of this principle." Looking to the future, the drive engineers and truck designers at Linde MH already have further developments in the pipeline.

Welschof says that, in future, "the hydrostatic system can act as a basis, for example, for connecting the drive principles of electric and internal combustion engines and offer the best of both."

Knock-on benefits of increased space The main components of the Linde hydrostatic drive are the hydrostatic pump, driven by the engine, and the two wheel motors. In contrast to hydrodynamic transmissions (torque converters), the connection between the pump and the wheel motors is via flexible hoses enabling the optimum installation of engine and transmission in the truck. This allows Linde truck designers to make much more space available for the operator.

This increased space leads to greater comfort and a slower buildup in fatigue over the working shift. Less fatigue means better concentration leading to higher productivity, less product damage and greater workplace safety.Moreover, a hydrostatic transmission does not need the clutches, differential, or gearbox of conventional trucks, which is reflected in higher efficiency in the power train resulting in lower fuel consumption as well as lower maintenance costs.

But it is the operating characteristics of Linde hydrostatic transmissions that make them perfectly suited to forklift truck applications. The ability to withstand rapid and frequent change from forward to reverse at speed without damage is crucial to durability. Linde trucks feature automatic, wear-free hydrostatic braking within the transmission which rapidly slows the truck to a halt before accelerating it in the opposite direction. Not only can Linde trucks with hydrostatic drive cope with this day in and day out, but this ability helps deliver higher levels of productivity.

Highly efficient in its use of engine power, the Linde hydrostatic drive uses less engine speed to complete its tasks resulting in lower fuel consumption and emissions.

All these threads of design philosophy and technical development can only tell part of the story. It is the truck itself, delivered to an end user and working in his or her application that provides proof of the benefit of these ideas. Albert Bartlett is Britain's leading grower and packer of root vegetables. Colin Campbell, production and HR director says that Linde trucks are "robust and well-built machines. They easily handle the dayshift and backshift demands associated with our full seven-day operations." Explaining why Albert Bartlett changed to Linde trucks, Campbell adds: "Fuel efficiency was our number one reason for purchasing Linde trucks. The build design was just right , which did directly contribute to our reasons for going with these trucks over the other products we tested."