Sinking on Soft Ground
Sinking is the slow burying of the foot when the bearing capacity of the ground under the leg is exceeded. Wet soil, sand, grass, fields and asphalt softened by summer heat are the riskiest surfaces. Sinking not only spoils the levelling result, it also changes the load distribution between the legs and puts twist into the body.
Sinking is mostly not instantaneous but a process that progresses over hours. When the system finishes levelling the reading is correct; as one or two legs sink during the night the angle drifts and in the morning the vehicle is found tilted.
- Prevention: use a wide base plate; enlarging the area lowers the pressure directly.
- Choice of spot: park on firm, well-draining ground if possible. If rain is expected, avoid grass and soil.
- Hot asphalt: in summer months the leg sinks into the asphalt and the surface is damaged when it lifts; a plate is mandatory here too.
- Monitoring: on long stays check the inclination display from time to time and repeat the cycle if needed.
If sinking has begun, retracting the legs and repositioning the vehicle is better than extending the legs further in the same spot. An extended leg both uses up stroke margin and reduces lateral stability. If the ground is doubtful, positioning the wheel chocks firmly becomes even more important.
Context in which this term is used: How to choose levelling leg capacity