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Drive & Control Systems for Forestry Machines
Systems for Cut-to-Length Machines
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CTL-machines are forestry machines that employ the Scandinavian Cut-To-Length method. According to the CTL principle the trees are cut and felled, delimbed and cut to certain lengths already in the forest. These machines are mostly so-called harvesters with wheel drives that are purpose-built for this process, but also feller bunchers are used. They are track-mounted, similar to excavators. The logs are carried with so-called forwarders to the roadside. The long-range transport from the roadside to the factory is done with trucks.
Hydraulics plays a significant role in all phases of the forest harvesting process. It would be impossible to design a state-of-the-art machine and at the same time meet the requirements of the users with other technologies available. The proven technology by Rexroth offers efficient and reliable components for any system solution in forestry technology.
Hydrostatic Drive
Harvesters and forwarders are nearly always equipped with closed-loop-controlled drive hydraulics. This ensures excellent driving comfort in the forest and very good controllability both in uphill and downhill driving. Today, both, the pump and the motor are usually controlled electrohydraulic pump proportionally by means of an electronic control device. The software used in the micro-controller automates drive characteristics with power limitation. This prevents the diesel engine from stalling in the case of overload situations.
Load-Sensing Working Hydraulics
Today, load-sensing systems are nothing unusual. Pumps of series A10VO and A11V(L)O are widely implemented in these machines. A good machine is characterised by precise crane functions. The spools in Rexroth valves are optimised to offer the operator excellent response characteristics and repeatable controllability under any operating conditions.
The Rexroth M4 load-sensing control block integrates all the advantages of advanced valve technology in a compact form:
- High flow rates
- High maximum pressure
- Integrated LS pressure relief valves and secondary valves
- Wide spectrum of different spool variants
- Compatibility with PWM control
- Integral electronics
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Relevant links for Forestry Machines
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