What is the difference between an automatic levelling system and manual chocks (ramps)?
A ramp makes a rough correction under the wheel and calls for manoeuvring; the automatic system drives chassis-mounted jacks from a tilt sensor, at one button.
The two methods do not do the same job. A ramp or chock goes under the wheel, so it corrects only at the point where the vehicle is standing and only by the height of the block; the accuracy is limited by eye and you have to move the vehicle back and forth at every attempt. Automatic levelling, on the other hand, drives 4 chassis-mounted 12V DC electric jacks from an integrated tilt sensor and goes down to an accuracy of 0.025 degrees. A ramp depends on the position of the vehicle; an electric system does not.
How the automatic system works
On the KTS200 the ASX103 levelling brain measures the tilt on two axes (front-rear and left-right) and the GRV485 control unit drives the 4 jacks accordingly. The order is fixed: first the jacks go down one by one and find contact with the ground, then front-rear is corrected, then left-right, and last of all the fine stage goes down to 0.025 degrees. The step-by-step account of the cycle is on a separate page.
Comparison
| Criterion | Ramp / chock | Automatic levelling |
|---|---|---|
| Power needed | None | 12V DC supply |
| Accuracy | Limited by eye | Down to 0.025 degrees |
| Repeatability | Calls for manoeuvring every time | The same result at one button |
| Installation | None, it sits in a locker | Permanently mounted to the chassis |
| Weight it adds to the vehicle | As much as the block you carry | A permanent addition to the unladen mass |
| Extra operating modes | None | Wind and Fine modes |
In short, a ramp is cheap and needs no electricity but calls for manoeuvring again and again; an automatic system runs from a 12V DC supply and gives a repeatable result at one button. The decision usually comes out of frequency rather than price: a block charges you in time and manoeuvring at every stop, while an automatic system charges you once in installation and permanently in weight.
Which one, and when, in the field
- If the slope is small and you are staying one night, a levelling block does the job.
- If more than three layers of block are needed it is better to move; using levelling ramps has a practical limit.
- If you stop often and use equipment sensitive to tilt (an absorption fridge, grey water drainage), an automatic system suits you.
- On very sloping ground, using a ramp together with the automatic system means the jacks spend less stroke.
- On soft, wet ground a block sinks in under the wheel; on the same ground the jacks do not work either without a foot plate. Both methods call for ground preparation.
The rule that does not change in either method
The important common rule holds for both methods: do not lift all the wheels off the ground. Jacks do not take the place of the parking brake; the handbrake is applied and wheel chocks are used - jacks do not take the place of chocks. An automatic system does not solve every problem either: on soft ground a jack sinks in, when the jack stroke runs out the system cannot reach the level point, and if the battery is weak the movement slows. In those three cases the answer is not in the system but in the parking spot and the preparation.
What to do
Look at how often you use it: if you stop a few times a year and on tidy campsites, blocks are enough. If you stop through the season, on different kinds of ground, and use an absorption fridge, an automatic system gains you both time and equipment life. Whichever method you choose, do not disturb the order after parking: position first, then levelling, and the services and the fridge last. Before deciding, think back over last season: at how many stops did you take the blocks down and put them away, and how many times did you have to reposition the vehicle? That number on its own usually tells you the right method for you.
The full topic: RV automatic levelling guide