In the early 1970’s, I had a couple of these Komatsu D155W amphibious dozers in model form, which were made by Shinsei mini power of Japan. They always reminded me of something you would expect to see coming out of a pod in an episode of Thunderbirds! But, in fact, these amazing remote controlled machines were real, and a number of them saw action on various river de-silting jobs in Japan and in the Philippines.
These machines first appeared in 1972 and were powered by Komatsu’s own engines, although an earlier example, the D125W was powered by a Cummins power unit. The machines had an on land weight of 43,000kg and could work in water up to a depth of 7 metres.
Looking at this video, I find it hard to believe that the machines could ever have been very effective compared to a conventional backhoe dredging set up, but it is a very clever piece of engineering to say the least.