What happens if the lift lever enters the "continuous pumping" sector?
On quadrant-type Lift-O-Matik systems, if the position lever goes past the transport position into the continuous pumping sector, the relief valve stays permanently open. In that case the hydraulic oil heats up quickly and the spring in the mechanism gradually loses its tension. The lever must be left in the transport position and must not be taken past the bend of the quadrant.
On quadrant systems the travel of the position lever is divided into two zones. The part near the bend of the quadrant is the transport position: the linkage is up and the system settles into balance. The sector beyond the bend is the continuous pumping zone; the pump keeps delivering, the pressure rests against the relief valve setting and the valve dumps continuously.
The consequences:
- The oil temperature rises quickly, shortening the life of the oil and the seals.
- Because the spring in the mechanism stays under constant high tension, it loses its tension over time and the setting drifts.
- The pump power wasted for nothing puts an extra load on the engine.
This also explains why the pull travel limits of the LFT20 and LFT54 are meaningful: the LFT20 pulls the cable 60 mm and the LFT54 50 mm. The aim is to move the lever within a certain angular range, not to force the mechanism to its end stop. When setting the cable length during installation, make sure the lever rests in the transport position; if you connect the cable too short, the kit can push the lever into the pumping sector on every command.
Full topic: Converting a tractor hydraulic lever to electronic control