transducer 40 uses the footing plate 44 to seat on the casing and the four screw bolts 45 to clamp the four columns onto the casing therefore the tip depth transducer 40 can be firmly mounted onto or completely removed from the top of a casing in a drill hole the coupled sampler and drill rods can be inserted into or retrieved from the tip depth transducer 40 as shown in fig5 and 6 in the present configuration the casing is used to support the tip depth transducer other means to support the tip depth transducer 40 can also be developed during insertion or retrieval the sampler or a drill rod 22 frictionally contacts with the three wheels and causes them to rotate about their rotational axes the rotational axis of the first wheel 42 is bolted to the travel shaft 50 the first wheel 42 and the travel shaft 50 together can move horizontally above the podium plate the two springs 49 urge the travel shaft and the first wheel against the drill rod 22 or the sample when it is switched off the lock stops the rotation of the first wheel 42 about its axis when it is switched on the first wheel can freely rotate about its axis the first electrical signal measures the degree of the rotation of the first wheel 42 about its axis the first rotation sensor 42 captures the first electrical signal and transfers it into the micro process controller through the first signal cable 36 in real time at a first.