Every country has different rules regarding the maximum permissible weight of trucks. In Hungary the maximum weight of a 4-axle truck including cargo is limited to 30 Tons, in Malta that same truck is allowed to weigh 44 Tons. Quite a difference!
So when designing a CPT rig there is no such thing as “standard”. First of all one has to listen to its client and determine his technical and budgetary requirements. But it is also important to look at the legal limitations.
In the picture a pretty special CPT crawler is depicted. The client needed a crawler capable of pushing 200 kN. That implies an own weight of approx. 21.5 Tons. The CPT crawler was due to be operated in Belgium, where the maximum weight of a 4-axle truck is limited to 32 Tons. Considering the fact that the 4-axle truck weighs around 10 Tons and that the crawler will carry around 700 kg of CPT equipment, there was little to no “weight” left for the construction of the carrying chassis on the truck.
It is for this reason, that we have decided to project as much weight in the crawler itself (needed as counterweight for the 200 kN CPT tests) and to keep the carrying chassis as little and light as possible. The CPT crawler is therefore equipped with 4 extremely long levelling jacks mounted on pivot arms. The crawler can lift itself from the truck (by wireless remote control) and the truck can drive from underneath the crawler. The crawler is subsequently lowered and is ready for CPT testing. In this ingenious way the entire combination remained within the weight limit of 32 Tons.