Hydrostatic tractor drives in inline design

High performance, excellent comfort, low energy consumption

As a specialist in hydraulic drives for mobile machines, Linde Hydraulics has a wealth of experience in developing and manufacturing continuously variable drives for agricultural machinery. Linde Hydraulics’ experience covers both hydrostatic drive units and CVT gearboxes in powerful agricultural machinery, for which they supply the power split hydraulic system.

While the CVT gearbox is making its mark in the upper market segment, Linde has developed a solution for the mass-produced tractor market, i.e. for mid-range segments, which provides similar driving comfort to that of a CVT gearbox, but is simpler in its design. At the heart of this solution is the K-02 compact unit, which can be fitted in a CVT gearbox, but is now also available as a fully hydrostatic system for installation in standard drive trains.

The new K-02 compact drive unit fits in conventional drive trains and enables direct torque transmission from the drive motor to the PTO shaft.

The unit consists of an HPV-02 variable displacement pump fitted in a back-to-back arrangement to a fixed motor HMF-02. This connected motor is directly supplied with oil, thereby eliminating the need for the usual high-pressure hose. And as the unit can be fitted directly to the gearbox, less space is required for the drive unit and PTO drive. The inline design featuring a hollow shaft enables direct torque transmission from the drive motor to the PTO shaft.

These design features will primarily benefit tractor manufacturers, but users will benefit from the new drive concept to at least the same degree: the fully hydrostatic drive guarantees significantly enhanced driving comfort and performance. It enables the driving speed to be controlled accurately and variably, and also facilitates highly efficient, dynamic operation with all attachments.

The available power is always ready, in accordance with needs, at the drive unit and at the PTO drive. The combination of hydrostat and diesel engine at the controller level ensures that the necessary power is available in every load situation.

In practice, this means high performance combined with low fuel consumption in all operating situations. Drivers can also devote their full attention to tasks such as monitoring the work functions because they no longer need to change gear. And when carrying out precision tasks, their work is made easier by being able to accurately control the driving speed. The tractor can also be started with the highest level of precision — regardless of the attached load.

Compact units used in CVT drives are available for engine power from 120 to 280 hp and in nominal sizes from 55 to 105 ccm/rev. The introduction of compact units for fully hydrostatic drive solutions will see Linde enter the 40 to 120 hp power class. Actuation is carried out either hydraulically or electro-hydraulically; the two control types proven in hydrostatic closed circuit drives. Both methods provide excellent control characteristics. The electro-proportional E2 control provides the highest level of comfort and safety by swashing back the pump in a controlled manner in the event of any system faults.

This enables both manufacturers and users of tractors in the mid-range power segment to benefit from the advantages of the "LinDrive" drive concept: The fully hydrostatic drives stand out from the crowd thanks to maximum dynamics, precision, energy efficiency and reliability.