A LOADING MACHINE EQUIPPED WITH A FIRST AND A SECOND PUMP SUPPLYING PRESSURE OIL TO AT LEAST ONE HYDRAULICALLY DRIVEN WORKING COMPONENT, SUCH AS A HYDRAULIC PISTON-CYLINDER DEVICE OR HYDRAULIC MOTOR

摘要

A loading machine equipped with a first and a second pump for supplying hydraulic oil to at least one hydraulically operated working component, such as a hydraulic piston-cylinder device or a hydraulic motor having a varying oil-pressure and flow requirement, wherein the pumps can be connected together for mutual coaction, when necessary. The second, larger pump is a fixed displacement pump. The first pump is provided with a pump regulator which is influenced by the load pressure prevailing in the hydraulic system and is intended to influence the first pump in a manner to maintain between the outlet of the pump and the load pressure on the pump regulator a pressure difference determined by the pump regulator, wherein the first pump is connected to the working component via a variable constriction. A control device is operative to connect the second and larger pump to the system solely when there is a need for a smooth increase in flow which cannot be achieved solely by the first pump.