Hydraulic driving device for concrete agitating drum responsive to engine speed

摘要

An agitating drum driving device comprises a hydraulic motor (81) for rotating an agitating drum (1), and a swash-plate type hydraulic pump (10) connected to a combustion engine (60) to supply pressurized oil to drive the hydraulic motor (81). When the engine rotation speed is not higher than a predetermined speed, the swash-plate angle of a swash-plate (64) is regulated to keep a differential pressure between a pressure of the pressurized oil and a load pressure acting on the hydraulic motor (81) constant. When the engine rotation speed rises above the predetermined speed, the flow rate of the pressurized oil is increased as the engine rotation speed increases while relatively decreasing an increasing rate of the flow rate of the pressurized oil with respect to an increase rate of the engine rotation speed as the engine rotation speed increases.