共查询到20条相似文献,搜索用时 62 毫秒
1.
<正>拖拉机动力输出轴的功用是将拖拉机发动机的部分旋转动力乃至全部动力以旋转动力方式传递给机具,为作业机具提供动力。目前,各种农业机械作业所需动力都是来自拖拉机,如旋耕机、施肥机、播种机、移栽机、喷雾机和背负式联合收获机等,它们都是由拖拉机牵引行走的同时,并依靠拖拉机的动力输出提供动力来完成工作。还有一些机械如脱粒机、排灌机、搅拌机、发电机等,可由动力输出轴直接带动或通过带轮传动来进行固定式作业。 相似文献
2.
3.
<正> 就拖拉机与农业机械而论,一种产品是否优良很大程度上取决于功率储备的大小和液压化的程度,后者可以保证整机通过更换各种悬挂机具完成广泛的作业。 工作压力是衡量液压传动技术水平的综合指标,它既决定液压传动结构的金属消耗量,也决定其动力性。所以,液压传动领域内的技术进步同液压系统压力的提高是紧密相连的。 自1958年以来,基洛夫格勒拖拉机液压件厂就已开始从提高工作压力和可靠性着手来改进齿轮泵。 相似文献
4.
目前,小型拖拉机开始采用静液压传动元件,简化传动系的结构.提高整机负栽适应能力.从静液压传动和传统机械传动的对比、HST元件和发动机的匹配、控制方式及刹车能力几方面阐述了HST在拖拉机上的应用. 相似文献
5.
拖拉机液压机械无级变速器速比匹配设计与实验 总被引:6,自引:0,他引:6
液压机械无级自动变速器能够根据拖拉机作业模式的差异,实现不同作业模式下发动机转速、转矩的匹配.将液压机械前进区段设计为等比四区段,各区段传动公比φ为1.88,纯液压区段用于拖拉机低速爬行作业以及起步.基于液压机械换段等比传动的连续性,对各区段齿轮的参数以及传动比进行设计,并对变量泵和定量马达的匹配进行选型.加载实验中模拟拖拉机不同作业模式的负荷,进行了液压机械各区段下的发动机最佳经济点的速比匹配.验证了变速箱在各区段之间的平稳换段以及拖拉机平稳加速的连续性响应. 相似文献
6.
7.
8.
《农业装备与车辆工程》2000,(3)
一种由齿轮传动代替原有链条传动的手扶拖拉机 ,由东风农机集团公司投放市场。该种拖拉机早在 80年代就由常州拖拉机厂开发研制成功 ,采用全齿轮传动箱总成取代原有的链条传动箱总成。根据目前手扶拖拉机用于农田作业 ,要求功率损失小、传动效率高等要求 ,结合国内拖拉机的使用情况 ,改进设计后 ,最新推出了该系列手拖。该手拖是东风 1 2型系列手拖的变型产品 ,与传统的手拖相比有以下几个特点 :一是采用齿轮传动 ,传动效率高 ,性能可靠 ;二是可与原有链条传动箱互换 ;三是可配置齿轮泵 ,改装成翻斗车 ;四是速度有所增高 ,农田作业效率提高 … 相似文献
9.
10.
齿轮泵作为拖拉机上液压系统的加压元件,其工作状态直接影响着拖拉机的工作性能。为此,通过Pro/E参数化建模的方法,构建了齿轮泵轮齿的三维精确模型;利用Pro/E和ANSYS之间的无缝连接接口导入到AN-SYS中,采用solid95单元建立其质量较高的有限元模型,并对其复杂的边界条件进行简化处理,然后对其进行接触非线性有限元分析,得到了齿轮接触应力、应变的分布云图以及最大接触应力,为拖拉机齿轮泵的改进及优化提供依据。 相似文献
11.
12.
13.
14.
15.
《Journal of Agricultural Engineering Research》1998,69(3):249-254
A model to represent the discolouration of dried powder of carrots as a function of temperature was developed. Two types of carrots, Asian and European, containing large amount of lycopene and β-carotene, respectively, were tested. The dried powder was stored under an atmosphere with O2and at three different temperatures, 5,20 and 35°C. The surface colour of the powder was monitored during storage by a Hunter colour ratioa/b. In the proposed model, the rate of oxidation was assumed to be represented by the product of the fraction of concentration of oxidized pigment at arbitrary time and a specific rate of oxidation of pigment. The rate parameters in the proposed model were calculated by fitting the experimental data with smooth curves by trial and error at the end of the induction period but before discolouration took place. The frequency constant and activation energy, expressing the temperature dependence of the rate parameters, were expressed by the Arrhenius relation. The simulation results of a Hunter colour ratioa/bof dried powder at 25°C showed good agreement with the experimental data, suggesting that the proposed model was effective for the prediction of discolouration of dried powder of both types of carrot. The use of the induction period in the manner described may enable the shelf life of dried powder to be predicted. 相似文献
16.
感官检验棉花的品级,这是农村常见的一种检测手段.它的一个主要特点就是存在不确定性.这是由于检验员的品级检验水平存在一定的差异,其中有很多因素制约着检验的结果.文章对影响感官检验结果的因素进行了系统的分析. 相似文献
17.
18.
从灾害经济学的角度探讨了城镇供水优化调度的必要性和可能性,认为在缺水不可避免的情况下,对供水进行优化调度可以减小缺水带来的损失,产生较好的减灾效益,特别是可以大大减小严重干旱的灾害效应。并根据水资源的特性,提出了缺水损失的计算模式以及优化调度的原则和方法。 相似文献
19.
20.
The fractional outflow rate of water from the rumen, measured as the rate of disappearance of the chromium complex of ethylenediamine tetra-acetic acid, was related to a number of dietary factors. A multiple regression equation was derived which expressed fractional outflow rate as a function of the intakes of dry matter, ash, acid-detergent fibre and crude protein.The data analysed consisted of 243 observations for sheep on 59 diets, including forage, concentrate and mixed diets. The ranges covered by the data were: fractional outflow rate 0.7–3.6 day?1; dry matter intake 560–1400g/day; ash 4–30%, acid-detergent fibre 7–41%, crude protein 5–26 % of dry matter; there were no observations for sheep of less than 34 kg liveweight.The equation accounted for 56·3 % of the total variance. Between-sheep variance could not be calculated for the whole of the data but was undoubtedly substantial since, for a sixth of the data, it was known to account for 38 % of the total variance. 相似文献