Levelling Jack
A levelling jack is a jack sized to carry a portion of the vehicle's weight and whose length can be changed in a controlled manner. The angle of the body is corrected by extending the four jacks to different lengths. For the D3501-1142 jack in the KTS200 kit, the stated figure is a load capacity of 2000 kg per jack.
What separates a levelling jack from a support jack is the load path. In a levelling jack the load is transferred from the base plate to the screw or scissor mechanism and from there to the chassis mounting bracket, and this path is calculated for that load. The length of the jack must also be measurable/controllable, because the angle correction is made by the difference in length.
- Drive: electric jacks with 12V DC motors are common in caravans; hydraulic systems are seen more on heavy motorhomes.
- Self-holding: a screw mechanism keeps its position even if power is cut, and does not run back.
- Placement: the four jacks are positioned so as to form as wide a rectangle as possible; the larger the base area, the less stroke is needed for the same angle correction.
When choosing capacity, remember that the jacks do not lift the vehicle into the air. The jacks carry part of the weight while the wheels keep contact with the ground. The criterion for assessment is therefore that the total load capacity leaves a sufficient margin relative to the vehicle mass.
Context in which this term is used: Guide to automatic RV levelling