The low speed hydraulic motors (Geroler) are rotary hydrostatic motors with internal gearing and planetary movement of the runner. They convert the hydraulic energy in mechanical energy. The hydraulic motors are used for carrying-away implements and machines like: agricultural machines, hoinsting and transporting machines, implements and machines for the light industry, forestry industry, naval implements on deck, machine-tools, etc. The motors can be used with: - Internal drainage - if the return is lower than 10 bar- the drain line is shut off. - External drainage - if the return is 10- 50 bar, the orifice is settled by piping.