The original adjust the style the hydraulic pressure circle belt unit for belt conveyer use and protection to do in order introducing in the way of the hydraulic pressure circle belt,the secure use to the hydraulic pressure circle belt unit possess specified reference value.

It is put forward that the hydraulic system is a grey one and its faults possess grey property because of the particularity of the ship hydraulic equipment and its faults,which lays a basis for using the grey system theory in fault diagnosis of hydraulic equipment.

Improvement of propeller s installation with hydraulic apparatus;