Abstract: P gear is the most common kind of gear in the car, P block parking lock mechanism is a core device of automatic transmission, assembled in the automatic transmission power output shaft, through the movement of the locking mechanism, cut off the output shaft power, so that the car on the ramp safe, reliable, long time stop, prevent the car slip slope. This paper takes a car with engine front and rear as an example, and introduces the structure principle, functional requirements, working state and mechanical properties of the locking mechanism of parking P block, so as to provide a reference for the design and development of parking mechanism.

Key words: Automatic transmission; P gear; Locking mechanism; Ratchet; Pawl; Front engine rear drive; Grade

摘要： P 挡位是汽车排挡中最常见的一种挡位，P 挡驻车锁止机构是自动变速器的一个核心装置，装配于自动变 速器动力输出轴上，通过锁止机构的运动，切断输出轴动力，使汽车在坡道上安全、可靠、长时间驻停，防止汽车 溜坡。文章以发动机前置后驱车辆为例，通过分析驻车 P 挡锁止机构的结构原理、功能要求、工作状态及力学性 能方面的介绍，为驻车锁止机构设计开发提供参考依据。

关键词: 自动变速器；P 挡；锁止机构；棘轮；棘爪；前置后驱；坡度