| 摘要 |
A PRESSURE REGULATING VALVE (97) IS PROVIDED IN A HYDROSTATIC, CONTINUOUSLY VARIABLE TRANSMISSION HAVING A HYDRAULIC CLOSED CIRCUIT INCLUDING A HYDRAULIC PUMP (P), A HYDRAULIC MOTOR (M), AND A HIGH PRESSURE OIL PASSAGE (53) AND A LOW PRESSURE OIL PASSAGE (52) DISPOSED BETWEEN THE HYDRAULIC PUMP (P) AND THE HYDRAULIC MOTOR (M). THE PRESSURE REGULATING VALVE (97) IS PROVIDED FOR RELIEVING THE HYDRAULIC PRESSURE IN THE LOW PRESSURE OIL PASSAGE (52) INTO THE HIGH PRESSURE OIL PASSAGE (53) WHEN THE HYDRAULIC PRESSURE IN THE LOW PRESSURE OIL PASSAGE (52) EXCEEDS A PREDETERMINED VALUE. THE PRESENT INVENTION PREVENTS EXCESSIVE PRESSURE IN THE OIL PASSAGES, PARTICULARLY IN THE NORMALLY LOW PRESSURE PASSAGE THAT SERVES AS A HIGH PRESSURE SIDE DURING A SPEED REDUCING OPERATION, E.G. AN ENGINE BRAKING OR REVERSE LOAD SITUATION.
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