Bucket chain excavators are heavy equipment used in surface mining and dredging. It uses buckets on a revolving chain to remove large quantities of material. It has similar characteristics to bucket-wheel excavators and trenchers. They remove material from below their plane of movement, which is useful if the pit floor is unstable or underwater.
Bucket chain excavator Wikipedia
The first documented use of a bucket chain excavator was in 1859. It was developed by Alphonse Couvreux, a French entrepreneur. The excavators from Couvreux were used in the construction of the Suez Canal.