机械毕业设计（论文）履带拖拉机变速器改进设计ⅱ（全套图纸）.doc

履带拖拉机变速器改进设计Ⅱ
摘 要
本次设计任务为：履带拖拉机变速器的改进设计。
变速箱的结构对拖拉机的动力性、经济性、操纵的可靠性与轻便性、工作噪声等都有直接影响。变速箱主要用来改变发动机传到驱动轮上的转矩和转速，目的是在起步、爬坡、转弯、加速等各种行驶工况下，使汽车获得不同的牵引力和速度，同时使发动机在最有利的工况范围工作，设有空档和倒档，并设有动力输轴。
为适应农业耕作的复杂工况，要求变速箱采用多档位,以使变速箱有较宽的速比范围，以使拖拉机能高效率高质量地完成各种作业。该变速器采用手动啮合套换档机构，空间三轴布置方式，结构紧凑。
本次设计按照传统设计方法，本着半经验半理论的设计原则通过类比法确定方案，参照已有变速箱结构，最后以机械零件的强度和刚度理论对确定的形状和尺寸进行必要的计算和校核，以满足约束条件，进而缩短设计周期，降低设计成本。

关键词：拖拉机，变速箱，啮合套，改进设计
IMPROVED DESIGN Ⅱ OF TRACKED TRACTOR TRANSMISSION
ABSTRACT
This design is an improving design of the tractor transmission.
The structure of the transmission has direct effect on the tractor’s traction performance and economy performance as well as its reliability, working noise and so on. Transmission is mainly used to change the engine torque and speed reached on the driving wheel, the aim is to acquire different traction and speed in various driving conditions like starting, climbing, turning and accelerating. At the same time the engine can work in optimum condition. The transmission has reverse gear ，zero gear and power transmission shaft.
To meet the complex farming conditions, the transmission should have a multi-gear so that the transmission speed ratio can be changed in a wide scope. Then the tractor can complete all kinds of operation efficiently and high-quality. The transmission adopts the manual shift meshing sets, triaxial space layout. And its structure is compact.
The design of transmission uses the traditional design method. Based the semi-empirical and semi-theoretical design principles, the drive scheme is determined by analogy. In order to meet the conditions, shorten the design cycle and reduce design costs, the shape and size of transmission are calculated and checked by the mechanical parts strength and stiffness theory.
Key words: tractor, transmission, meshing sleeve, improved design
符 号 说 明
发动机标定功率，
发动机标定转速，
传动系总传动比
履带驱动轮半径，
拖拉机