LOAD CONTROLLER FOR HYDRAULIC TRANSMISSION DEVICE FOR WORKING VEHICLE

摘要

A load controller for a hydraulic transmission device for a working vehicle, where structural components for load control is prevented from deteriorating and the load controller can be downsized and simplified in its structure. In a working vehicle, power from an engine (E) is divided to a working machine system and a travel system and drive them. The travel system has a hydraulic transmission device (1). In the hydraulic transmission device (1), a hydraulic pump (2) driven by the engine (E) and a hydraulic motor (4) driven by the pump (2) are connected by a closed hydraulic circuit. The load controller has a bypass oil-path (8), an opening/closing valve (9), and an opening/closing valve-controlling means. The bypass oil-path (8) connects an oil path (3a), of the closed circuit, that is on the high-pressure side in forward traveling to an oil path (3b) that is on the low pressure side in forward traveling or to an oil tank (T). The opening/closing valve (9) opens and closes the bypass oil-path (8). The opening/closing valve- controlling means senses load on the engine (E) during work traveling and increases the degree of opening of the opening/closing valve (9) as the load increases.