The Hydraulic Infinite Linear Actuator for Efficient and Flexible Timber and Agricultural Logistics


  • Magnus Landberg
  • Magnus Sethson
  • Petter Krus



hydraulic actuator, incremental control, digital hydraulics, logistics


In forestry and agriculture industry, robust and power-dense hydraulics have long played an important role for a rational and cost-effective logistics. In these fields there is a trend towards longer, larger and heavier vehicles and machines. Within the forestry business there is a need to develop transport vehicles with lower energy consumption. This can be done by improving the vehicles' aerodynamics. The air resistance of unloaded timber trucks and timber trains will be significantly reduced if stakes and banks are put together. Furthermore, there is a need to place banks and stakes at individual distances individually to accomplish different load combinations. In agriculture when sowing, it is an advantage to be able to flexibly position row units on a seed drill in optimal distances from each other to secure productive and sustainable farming. However, most present seed drills have fixed row distances and thus have a low adaptability for different crops or soil conditions. There is also a need for a faster transport of the seed drill between different fields.

Future actuation systems for forestry and agricultural vehicles and machines can be improved by utilizing a new sort of hydraulic linear actuator technology, the Hydraulic Infinite Linear Actuator (HILA). HILA technology also has an impact on heavy and dangerous manual steps when changing banks and stakes on timber vehicles. The adjustment can be controlled from the cabin, thus eliminating manual steps. Heavy bank elements on a timber vehicle can be positioned individually with high locking force. In the agricultural context, it is possible to quickly change between different inter-row spacing on a seed drill when using HILA technology, enabling a multi-purpose seed drill and inter-row cultivator. HILA long stroke capability also facilitates a smooth folding into a compact transport position. With the bills are gathered, a low center of gravity will be accomplished. This enables a more stable vehicle dynamics and enables a higher speed.

HILA is based on a well-known hydraulic clamping element technology, where the piston and the piston rod can be coupled and uncoupled by means of the clamping element. The HILA invention, in its simplest usage, provides new features to hydraulic cylinders, such as providing very long strokes and small chamber volumes, which means high stiffness and low capacitance. However, the invention also enables lower weight and volume of the actuator when compared to conventional hydraulic cylinders. This is a new way to generate and distribute mechanical linear movement and force by using hydraulic actuators in a cost effective way. The technology also represents a new sort of digital hydraulics. The technology is best suited for relatively slow dynamics and where the movement pattern is well-known.