Continuous Pumping Zone
The undesirable sector in which the dial lift control goes past the transport position and holds the relief valve permanently open. In this zone the pump keeps delivering, the oil returns to the tank through the relief valve and all the hydraulic power is turned into heat. The result is oil heating, loss of efficiency and the mechanism springs losing their tension.
Anything beyond the detent point of the dial is not needed for lifting; the linkage has already reached its upper limit. Taking the lever further only holds the system at the pressure limit. As long as the relief valve stays open, the flow delivered by the pump runs to waste under high pressure and is converted directly into heat.
- As the oil temperature rises, viscosity falls, internal leakage increases and the linkage drops faster under load.
- Long exposure shortens the life of springs and seals.
- The symptom is simple: after a long transport, the hydraulic housing becomes too hot to touch by hand.
This risk explains why the stroke limit is set as it is on electronic retrofit kits. The LFT20 pulls the cable 60 mm and the LFT54 50 mm; the fact that the kit does not push the lever all the way is deliberate. When adjusting the cable tension during installation, your target should be to bring the lever to the transport position, not to push it to the end of the dial.
The context where this term is used: Converting a tractor hydraulic lever to electronic control