352履带拖拉机（中央传动及转向离合器设计）摘要中央传动用来增加传动系的传动比,以达到减速增扭的目的,通常还用来改变转矩的传递方向,使转矩从纵置的变速箱输出轴传递给横置的中央传动两侧输出轴。
中央传动应有适当的传动比,以保证拖拉机具有良好的牵引性与经济性;结构应紧凑,以减小后桥尺寸和和质量,保证后桥有足够的离地间隙；齿轮装置应有足够的承载能力和支承刚度,如系锥齿轮副,则还应便于调整。
中央传动的齿轮形式目前主要有圆柱齿轮和圆锥齿轮。
圆柱齿轮结构简单,加工较容易,在传动时不致产生轴向力。
但仅适用于采用横置变速箱的拖拉机。
而圆锥齿轮应用则较为广泛。
履带拖拉机在行使过程中，需要经常改变行驶方向，这就需要有一套能够按照司机意志来改变或恢复拖拉机行驶方向的专设机构，它将司机踩下转向离合器踏板的动作转变为车轮的偏转动作，这就是所谓的转向系统。
转向性能是保证车辆安全，减轻驾驶员劳动强度和提高作业效率的重要因素。
转向离合器转向系统由于构造简单，制造方便，维修容易，在拖拉机上广泛采用。
它具有转向半径小，直线行驶性好等优点。
但由于传递的转矩较大，只得采用多片式离合器，而多片式离合器分离彻底性比较差。
这对转向离合器来说，除了使摩擦面的磨损略微增大外，对整机性能没有太大影响，不像主离合器分离不彻底会造成换档困难。
关键词：中央传动，转向离合器，锥齿轮，转向系统352 TRACKED TRACTOR（CENTRAL TRANSMISSION AND STEERING CLUTCH DESIGN）ABSTRACTCentral spread to use to increase to spread to move to fasten of spread and move ratio, the purpose that to attain to decelerate to increase to twist, usually return to use to change the torque to deliver the direction, make torque place become soon the box outputs the stalk to deliver to horizontal place central to spread to move the two sides exportation stalk.Central spread to move and should have appropriate of spread and move ratio, with the assurance that the tractor has to lead the sex and economy goodly; structure should tightly packed, after to let up the bridge size and and quantity, the assurance is behind the bridge has to leave a ground of cleft enough;The wheel gear device should have the enough loading ability and pay to accept just degree, return if department the bevel gears is vice, should easy to adjustment.Central spread the dynamic wheel gear form to mainly have the cylinder wheel gear and the bevel gearses currently.The cylinder wheel gear structure is simple, processing to compare easily, produce the stalk toward dint unlikely while spread move.But be applicable to the adoption only horizontal place to become soon the tractor of the box.But the cone wheel gear the application then compare extensively.The track tractor professional makes in the process, needing to usually change to drive the direction, this need to be have a set of can change or recover the tractor to drive the particularly establish of the direction organization according to the driver will, it deflect the action change that the driver tramples bottom to change direction the clutch pedal for the felloe action, this is to change direction the system so calledly.Change direction the function is to guarantee the vehicle safety, easing the pilot the labor strength and raise important factor of the homework efficiency.steering mechanism changes direction the system because of structure in brief, make convenience, maintain easily, in the dalliance on board extensivedoption.It has the radius of change direction small, drive sex good etc. advantage straightly.But because the torque that deliver compare greatly, have to several type clutches of adoption, but several types clutch separate thoroughly sex is worse.This says towards steering mechanismcome, in addition to making rub to face of wearing away the inching aggrandizement, having no to the whole machine function to affect too greatly, be unlike the main clutch separation ill success and will result in shift gear the difficulty.Key words: Central transmission , steering clutch ,bevel gears, steering system目录第一章前言 (1)第二章中央传动及转向离合器概论 (2)§2.1 履带拖拉机转向机构概述 (2)§2.2 中央传动的概述 (3)第三章中央传动及转向离合器方案分析 (5)§3.1 转向离合器方案分析 (5)§3.2 中央传动方案分析 (10)第四章转向系统设计计算 (14)§4.1 螺旋锥齿轮的计算 (14)§4.2 转向离合器设计计算 (17)§4.3 带式制动器的设计计算 (19)第五章主要零件的强度校核与计算 (21)§5.1 螺旋锥齿轮的承载能力计算 (21)§5.2 轴强度计算 (22)§5.3 轴承寿命计算 (24)第六章结论 (28)参考文献 (29)致谢 (30)第一章前言拖拉机的主要任务是用来拖带农机具进行各种田间作业（如翻地、播种、中耕等）；也可作为其他农业机械（如脱谷机、扬场机等）的动力；另外拖带拖车可进行运输作业。
