Method and an arrangement for managing and controlling the lifetime of a tree handling system for a forest machine

An arrangement for managing and controlling a lifetime of a tree handling system for a forest machine, which arrangement comprises:

• a crane carrying a tree handling unit, execution means each of which can create a force impact on the tree handling system and are activable with varying loading values (PT) through an operator's impact of a control stick, which via a hydraulic system adjusts a hydraulic flow to and from said execution means, wherein the arrangement further comprises:
• a control unit adjusted to receive information about the loading (PT) on at least one of the crane and the tree handling unit included in the tree handling system, wherein this information comprises,
• first sensor data from pressure sensors and second sensor data from position sensors,
• an actuator, which is coupled to the control unit and by which, through hydraulic flow reduction to at least one of the execution means, the loading (PT) on the tree handling system can be limited to a pre-determined maximum loading value (PTmax), wherein
• the control unit is arranged to determine one or a plurality of current partial damage values (SL, SM, SH), which during a normative activation period (At) is deemed to occur on the tree handling system at various loadings (PT) on the tree handling system,
• the control unit is arranged to determine a current key indicator, which describes a measured value (X) that relates to an operation of the tree handling system and is representative of a risk of partial damage in relation to specific reporting about a current running operating state of the tree handling system,
• at least one of the determined current partial damage values (SL, SM, SH) is compared with a normative partial damage value (SLX, SMX, SHX), for a normative operating state of the tree handling system corresponding to the current key indicator, and
• a change that affects the measured value (X) of the key indicator is determined in such a manner that the current partial damage value (SL, SM, SH) returns to or approaches a level corresponding to the normative partial damage value (SLX, SMX, SHX) for the current key indicator, and which arrangement further comprises,
• wherein said change of the measured value (X) is executed by the actuator coupled to the control unit.