Homemade Chain digging excavator 15hp

The parts I used to make the excavator are a 420cc cm3 engine with a power of 15 HP, a two-section hydraulic pump of 22 cm3 and 8 cm3, and two hydraulic motors. I used an oil flow regulator to set the speed of the excavator's drive and the speed of the hydraulic cylinder, thanks to which I can smoothly regulate the driving speed and the speed of lowering the arm while digging in the ground. The maximum digging depth is 105 cm/41 inch.
There are still a few things to improve, but the excavator works very well.