Position Control
A form of control in which every position of the control lever corresponds to a particular linkage height. Even if soil hardness changes, the linkage stays at the selected height; it is preferred on implements with low draft resistance such as cultivators, seed drills, sprayers and fertiliser spreaders.
In position control the system works like a feedback loop: the position of the lever represents the target height, while the mechanical feedback in the linkage mechanism represents the actual height. When the two are equalised the valve returns to neutral and the linkage stops there.
- Its advantage is repeatability: the same lever position gives the same height every time.
- Its disadvantage is that the implement does not follow the ground surface as it rises and falls.
- Raising the implement at the headland and returning it to the same position is easiest in this mode.
This repeatability also explains the field value of electronic retrofit kits. The position and precision modes of the ELF-812 aim to return repeatably to the selected height. The LFT20 and LFT54 operate the existing quick-lift mechanism from the cable; since the position setting on the tractor's dial is preserved, the linkage again descends to the previously set working height.
The context where this term is used: Converting a tractor hydraulic lever to electronic control