丫丫学语

Steering & Suspension

     The steering and suspension systems of a car are not only important for safety reasons but also enhances the comfort level of the vehicle. The two systems are directly related to each other, which is why they are always referred to together.

     First let’s look at the steering system. Motor turning system: On the automobile uses for to change or restores its travel direction to suppose the organization to be called the motor turning system specially. Automobile’s steering system is uses for to change the automobile travel direction and to maintain the automobile straight line travel organization. Its basic components are such：(1)TO change the control mechanism basically mainly by the steering wheel, the steering axle, the steering tube column and so on to be composed (2) Diverter becomes steering wheel’s rotation steering arm’s swinging or the rack axis straight reciprocating motion, and to changes the control force to carry on generally will also change the transmission direction(3) Changes the transmission system the strength which and the movement outputs the diverter passes to the wheel(knuckle),about and causes the wheel to carry on the deflection according to certain relations the organization. There are two basic types, standard mechanical steering and rack & pinion steering. The standard mechanical steering can be either power assisted or non-power. Rack & pinion is almost always power assisted although there are rare cases where it is not.

    The mechanical steering system changes the energy by pilot’s physical strength achievement, all power transmission are the machinery. He mechanical steering system by changes the control mechanism, the diverter and changes the transmission system three major part to be composed.

(1)Changes the control mechanism by the steering wheel, the steering axle, the steering tube column and so on to be composed, its function is rotates the pilot steering wheel’s control force to pass to the diverter.(2)The diverter(also often is called steering unit)is completes from the rotary motion to the translation (or approximate straightline motion) a group of gear mechanism, simultaneously is also in the steering system speed reducer drive. At present the commonly used toothed wheel rack type, follows round the world the crank to refer to sells the type, the worm bearing adjuster crank to refer to sells the type, to follow round the world-the tooth rack tooth fan type, the worm bearing adjuster hoop type and so on. We mainly introduce the first several kinds.

 

     Standard mechanical steering uses a series of links and arms to insure both wheels turn in the same direction at the same time. It hasn't changed much in all the years it's been used and is quite simple.

     Basically this is how it works; the steering wheel is connected to the steering box through the steering column. The steering box turns the rotation of the steering wheel 90° and, in the case of power steering, uses high-pressure fluid to help actuate the steering.

     The steering box has an arm attached to the output shaft called the pitman arm. This connects the steering box to the steering gear. The pitman arm is connected to one end of the center or drag link. In the other end of the center link is an idler arm. Between the idler and pitman arms, the center link is supported in the proper position to keep the left and right wheels working together.

     The inner tie rod ends are attached to either end of the center link and provides pivot points for the steering gear. From there it goes to the outer tie rod ends through an adjustment sleeve. This sleeve joins the inner and outer tie rod ends together and allows for adjustment when the front wheels are aligned. The outer tie rod ends are connected to the steering knuckle that actually turns the front wheels. The steering knuckle has an upper and lower ball joint that it pivots on and creates the geometry of the steering axis.

     As you can see, it's pretty simple. It is just a simple mechanical connection from the steering wheel to the front wheels. The weaknesses of the system are at the pivot points. The pivots are ball and socket joints that do wear out over time and will require replacement. Loose steering parts will make a car difficult to handle and will cause the front tires to wear out prematurely. That's why it's important to have the steering checked at least once a year. A great time to do it is when you're in for an oil change. I always instruct my mechanics to check the steering and suspension while the car is up in the air and they're waiting for the oil to drain out.

     Rack and pinion steering is somewhat different. The gear rack type diverter divides the both sides output type and among (or single end) the output type two kinds. The both sides output’s gear rack type diverter, changes the gear shaft as the transmission vice-host moving parts and installs through the bearing in the diverter shell, its upper extreme through spline and universal joint sliding yoke and steering axle connection. With the steering gear meshing steering rack level arrangement, the both sides with change the steering knuckle tie rod through a ball place to be connected. The spring presses through the briquetting the rack depending in the gear, guarantees ceaseless meshing. Spring’s pretightening up force available adjustment thread plug adjustment. When rotates the steering wheel, the diverter gear-driven, causes with it meshing rack along the end motion, thus about causes the steering knuckle tie rod to lead about the knuckle to rotate, cause to change the wheel deflection, thus realize motor turning.

   Basically it combines the steering box and center link into one unit. The steering wheel, through the steering column, is directly connected to the rack. Inside the rack is a pinion assembly that moves a toothed piston to move the steering gear. One end of the inner tie rod ends is connected to either end of this piston and the other end is connected to directly to the outer tie rod end. The inner tie rod end is actually threaded into the outer tie rod end and can be rotated to make adjustments during a wheel alignment.

     The advantage of rack and pinion steering is that it is more precise than the mechanical system. By reducing the number of parts and pivot points, it can more accurately control wheel direction and is more responsive. The down side of a rack and pinion steering system is that they are prone to leakage requiring replacement of the rack assembly.

     Rack and pinion steering is almost always used with a MacPherson suspension system. The bottom of the steering knuckle still pivots on a lower ball joint, but the top of the knuckle is connected to the MacPherson strut. In this system the outer tie rod end is connected to an arm on the strut housing itself.

     The MacPherson strut assembly replaces the upper control arm, front shock absorber and ball joint, increasing handling and responsiveness. It controls ride much the same way as a standard hydraulic shock absorber. It also keeps the front end aligned and eliminates, in some cases, the need for caster and camber adjustments. In most cases it also contains the front coil springs so care must be taken when you are replacing them.

     The down side is that they will eventually start to leak and will require replacement. They generally last longer than a conventional shock absorber and that may offset the greater cost of the MacPherson strut assembly. As far as replacement goes, some struts have an internal shock assembly that can be replaced separate from the rest of the housing and others have to be replaced as a unit.

  Before there was MacPherson struts, there was the basic hydraulic shock absorber. Again, something that hasn't changed too much since it's use started sometime in the 1930's.

     The operating principle of standard hydraulic shock absorbers is in forcing fluid through restricting openings in the valves. This restricted flow serves to slow down and control rapid movement in the car springs as they react to road irregularities. Usually, spring-loaded valves control fluid flow through the pistons. Hydraulic shock absorber automatically adapt to the severity of the shock. If the axle moves slowly, resistance to the flow of fluid will be light. If the axle movement is rapid or violent, the resistance is stronger, since more time is required to force fluid through the openings.

     By these actions and reactions, the shock absorbers permit a soft ride over small bumps and provide firm control over spring action for cushioning large bumps. The double-acting units must be effective in both directions because spring rebound can be almost as violent as the original action that compressed the shock absorber.

    Some vehicles came with a control that allowed the driver to select the ride type. By setting a control in the passenger compartment, a motor on the top of the shock would rotate a set of different sized valves inside the shock to change the damping ability of the shock. There are usually three settings, Firm, Normal and Soft.

     In an active suspension system there is a small sonar unit mounted in the bottom of the front bumper. The sonar unit sends a signal down onto the road and takes a "picture" of the road surface. This "picture" is sent to a control unit to automatically change the valving inside the shock to compensate for the road surface and maintain a smooth ride.

     Another important part of the suspension is the spring. The three types of springs used are the coil spring, leaf spring and torsion bar.

     Coil springs and torsion bars are generally used in the front whereas leaf springs are generally used in the rear. Coil springs are generally installed between the upper and lower control arms with the shock absorber mounted inside the spring. In some cases the coil spring is mounted on top of the upper control arm and a spring tower formed in the front-end sheet metal. Coil springs come in many "rates" and can be used to change the handling and ride characteristics of a vehicle.

     Leaf springs are made from layers of spring steel bolted together through the center of the leafs. This center bolt locates the spring to the axle housing and is attached to the housing with large U bolts. The ends of the leaf spring are attached to the frame or body through a shackle that allows the spring to flex without tearing out. The leaf spring also acts as control arms to keep the axle housing in proper position.

     Most trucks with a solid beam front end still use leaf springs on the front. Some cars, most notably the Chevrolet Corvette, use a single leaf spring, front and rear, transversely mounted. In other words the springs are mounted 90° to the center of the car.

     Okay, now I know that someone out there is saying that a torsion bar is not a spring. But in the technical sense it is. The torsion bar provides its spring action by the twisting of a flexible steel bar. This twisting of a steel bar provides the resistance to the up and down movement of the front end. There are two torsion bars, one for each front wheel. The rear of the torsion bar is mounted on the frame of the vehicle and the front is bolted the lower control arms. The big advantage of a torsion bar is that it is easily adjustable. By turning the tensioning bolts you can adjust the ride height very easily.

    Another component of the suspension system is the sway bar. Some cars require stabilizers to steady the chassis against front-end roll and sway on turns. Stabilizers are designed to control this centrifugal tendency that forces a rising action on the side toward the inside of the turn. When the car turns and begins to lean over, the sway bar uses the upward force on the outer wheel to lift on the inner wheel, thus keeping the car more level.

     Finally we have the control arms. The primary job of the control arms is to mount the suspension to the frame or body of the vehicle and to allow the suspension to move and keep it in it's proper place. They come in all shapes and sizes and are specifically designed to maintain the geometry of the suspension in a wide range of movement. The most common problem is that the bushings at the body mounting points wear out causing unwanted movement at worst and a terrible squeaking noise at best.

     There is a lot of math going into the suspension of a car. There are many forces and angles that have to be acted upon and maintained. If you notice any problems in the way your car steers or rides or you feel any body or steering wheel vibrations, you should have it checked out as soon as possible.

   Copyright © 2001 - 2003 Vincent T. Ciulla All Rights Reserved

 

曲曲折折经历了三个本本后，渐渐开始习惯了学校的电脑，也慢慢开始远离了space,于是，再也没有资格说别人懒了，发觉自己的日志一片空白，其实不是总得写点什么，是真的好多话想说，但是老是排不清个priority,也担心一说话就语无伦次，当然，加上自身的懒惰，不写日志开始变得无比自然。 

想到写的第一个冲动源于早晨的marketing课，今天是所有小组对论文的口头演讲。其实每个小组都辛苦的干了少则2，30，多则4，50页的报告了，没什么人把口头作业当回事，倒数第二节课，大家也就全当是放松。果然放松。。。有一组的论题是关于condom的marketing的，然后，讲到结束时我走了个神，等我回过神来，某同学已经开始在全班范围内发放condom了。。。教室一片哗然，各么有人说这个不好用，有人问同桌2欧卖给你要不要，有人问还有没有多（最后貌似多出来的给了我旁边的女生marine,小姑娘羞涩的说我不用，然后男生甲说没事，给你的朋友们用，marine谢过。。。）一片混乱后，大家精神振作，周五早晨8点的课人人都来了精神，于是所有人都期待着上次说要做sex在广告中的运用的那个小组，目光聚焦他们，然后人家来一句，不要看了，我们换主题了。。。权当是早晨的提神，我又不用，早晨已经喝过咖啡了。。。不过还是满有趣的，虽然更怀念去年économie sociale那个班级，因为人人都很sympa，不过每个班级有每个班级特色，多感受下也没什么不好。 

接下来，稍微sérieux点的东西。昨天前天结束了所有的翻译和法语课，小小的感伤，喜欢M. Vitry戏剧化的表情和音调，喜欢grammaire课前大家永远也不想停下的闲扯。昨天的小插曲，老师问我们会对下届要来格勒的学弟学妹说什么，土耳其mm很认真的说,老师，我的ex boyfriend明年要来交流了，为了表现她还是个好姑娘，她只要求老师上半学期让她的ex难受点，下半学期可以对他好点，课结束后还很认真地要把那个男生名字给老师。。。人家才20岁么，小孩子。。。西班牙的Nicholas永远要迟到半个小时以上，最后一节课，全班一起给了他个小惩罚，Henrick喊了声nicho来了，然后老师让全班装作考试状，他走进教室后，老师说不好意思，你只有半个小时的时间考试了，可怜的nicho一脸无辜相，完全不知道状况，最后他知道被耍后，一串西班牙脏话，不过人家心情还是很快就恢复了，毕竟前一天巴萨4比0横扫了拜仁。。

点点点表明还有很多事，不过在老师问到你们是不是每个人都会基本带着比较愉悦的心情回去的时候，忽然感性的神经就被触动。去年差不多这个时候巴黎回来，然后很无奈的接受要去格勒的命运，那个时候100个不情愿阿，傻傻的以为那边有雪山就会冻得冰天雪地。。。心不甘情不愿的来到这座陌生的城市。他在法国不算小，可是怎么也不能和上海比，周日商店是不开门的，campus静得像死了一样，可是不知不觉中，你爱上了这个小城，喜欢它的安静，喜欢四面的雪山，喜欢现在春暖花开的季节满眼的草地野花，喜欢那个虽然小但是能看到外面雪山和风景的游泳池。。。马上就要离开，忽然就不舍起来，这里超级nice的老师，会主动给你笔记，上课时见到我查字典会问我有什么地方不明白的同学，这里没有巴黎的繁华与奢侈，但也没有巴黎的冷漠，这里简单到周末想玩也只有爬山去郊区（当然还有酒吧，可惜没兴趣），但你就这样留恋起了她的简单.

那天游完泳和tuotuo一起坐在草地上吃冰淇淋，阳光肆无忌惮，树上的花瓣慢慢飘落，远方是阳光蓝天白云映衬下的阿尔卑斯山，禁不住就是一句：la vie est belle！那样的阳光下，暂时忘却了找工作，申学校的烦恼，什么都可以不想，只想就这么静静的待着，然后问自己，这样的日子以后还会有么？seize the time!

每年到年底总要盘点一下，不过或许是旅行太累，或许是人大了越来越懒，实在没有精力做个总结，但是按照惯例，给自己个交代，怎样都要在新年到来之前随便涂两笔。

 

又到巴黎，第一次没有人接，一个人下了火车一路直奔hotel,当中的重重曲折。。。其实还好，不过真让我顺顺利利的到我倒觉得奇怪了，呵呵，我的旅途一向充满波折。本来带了书想好好看看，问题是坐在火车上好累，到了旅馆更累，累得只有躺在床上写space的力气了。电视开着是当背景音乐的，怎么都要让他开着，回去又没的看了。。。tv5 monde放的是les chiffres et les lettres, Laurent啊，还是那么有魅力，又是一阵无限的回忆。没办法，人老了，就喜欢怀旧。

 

提前10分钟上了ter,有点小慌，下了ter已经想起上一次的提前30分钟到，想起第一次拖着几十公斤的行李踩着点上，gare，呵呵，有意思的地方。一路上看见披着银装的grenoble,心里一阵惬意，白色的山，白色的三角顶的小屋子，这是我小时候对于冬天最典型的描述，童话书上的，动画片里的冬天就是这个样子，我小时候的美术作业也是这么画冬天的，那个时候一直觉得上海没有冬天。。。下了雪并且有积雪的天才是我最初定义的冬天。越靠近里昂，雪就越少，然后是一片葱茏的绿，然后。。。是房子还是房子。下了ter，发现只有3分钟上tgv,结果，tgv迟到了10分钟，运气很好了，报道说今天下午巴黎这边的火车会有问题。然haoba后。。。又很经典的坐了和行驶方向相反的位子，那个晕的列。。。下了车，看见了一个男生捧了一大束的红玫瑰放在背后，窃笑了一下，浪漫的巴黎？冬天看到这样的情景是很温暖的。然后。。。省略一串，我找路么。。。反正总算到了。本来想好晚上要去卢浮好好逛一圈的，高估自己的体力了，本来也想晚上好好看书的，现在，电视，聊天，睡觉，积攒体力，demain sera un trop gros jour.

 

start to count down...

晚上就这么莫名被叫出去看marché de noël了，总结下来，的确很有过节气氛，但是如果周围建筑和布置换一下，感觉就是逛庙会。什么都是made in china,有人还明目张胆的在那边喊绝对不是fabriqué en chine，。。。扯吧，我明明在城隍庙见过这玩意。。。最最搞笑的是看到糖炒栗子，marrons chauds,这个有意思。等了半天的烟火表演才1分多钟。。。好难看。。。最终还是没看到père noël,失望。圣诞打折还没到，所以东西还是很贵，而且，衣服什么的真的不那么好看。说完了不好的，说说好的，真的很喜欢这边的节日气氛，然后第一次在格勒街头见到那么多人，开始想上海了。过节的时候可以在大街上临时搭建的旋转木马和碰碰车，看见小朋友玩的超开心，感觉好温馨。

 

报告写完了，作孽啊，这个20页憋得我，还好加了几张图表，估计老师一看图表就知道我的“用心”了。接下来圣诞后的4门考试，完全无从下手，太多了吧。本来一位éco sociale是最要命的，现在过了才发现，后面没有一门好过，估计只有旅游回来抱佛脚了，要看rp了。

 

现在开始倒计时，先甜后苦

先发泄下，什么beta版，以为化个妆就能唬人么，太差劲了，害得我一直登不上msn,当今天终于看到msn又连上时，觉得8.5长的好亲切啊。

天气开始转凉，到处都一样。这边有太阳的时候也不是那么冷，除了天气干燥是我一直抱怨的主题外，没有觉得这边比上海的天气糟糕多少，总结下来是：上海的天气够糟糕了。。。可能天气萧瑟的原因，看见在格勒的同志的日志也都阴沉沉的，节日前的小感伤吧，看了后自己也有些小郁闷。结束了5门考试后，暂时喘了口气，但其实还有份20页的报告和更恐怖的圣诞后的4门考试，可是心已经不知道飞在哪里了，满脑子想的只有Noël，好吧，还是要hold on,至少好好把报告完成，然后，这辈子再也不要搞什么économie sociale的东西了。。。

憋在屋子里没事的时候就会看电影和美剧，发现现在烂片真的越来越多，不过反正有些片子也就是切菜的时候吃饭的时候看着打发时间的，也就重量不重质了。前一阶段在linlin推荐下看了“十一月的练习曲”，唯一被感动到的一部电影，至少是我喜欢的风格。

其实就想写点什么，但是真的写了又不知道从哪开始到哪结束，感觉dissertation越写越多，怎么写blog的思路越来越乱了列。。。念傻了？dissertatioon写傻了？不清楚。

快要过节了，大家都cheer up吧，再烦再乱的事总会有解决的办法，没有解决的办法船到桥头也会自然直。。。

最后一段是让大家鞭策我的，放假前一定要把报告写好。。。然后，好好复习。

Merry X-mas to all!

其实这不是到了格勒的第一场雪，确切来说是第一次积雪。大家都跟我说格勒城里是不会下雪的，只有山上能见到雪，不过。。。都还没到12月呢。其实思绪很快就拉回了今年年初上海的那几场大雪，第一次见到银装素裹的上海，第一次堆起了自己的雪人。。。妈妈说上海昨天开始转冷了，呵呵，不知道今年会不会有大雪。时间真快，其实如果现在在上海，估计也和同学一样，纠结在工作的问题上，毕竟是大四的人了，而在这边，一点大四的气氛也没有，不过，要做的事还是很多，现在本来应该写下星期的exposé的，不过，心血来潮，就来涂鸦两笔。我讨厌走在已经脏了的白雪上，喜欢走在像棉花糖一样的雪上，很软，很舒服，回头一看，还有自己留下的一串脚。今天准备去拿titre de séjour的，妈妈说，如果天气不好下雨就别出门了，呵呵，那下雪算吗？其实等它等很久了，所以一空下来，就要赶紧去拿回来，虽然它长的很丑，但是，还是有无限的期盼。

昨天是iep de grenoble60周年庆，这个没气势的列。。。哎，用头发我都可以想象上外60周年的排场，这里，感觉像是在小学。bde的人让每个国际学生准备一道菜，我晕，正好该吃的都被吃完了。。。没什么有中国特色的，于是乎就把什么都炒在一起做了升级版的蛋炒饭。。。结果是，只有日本mm和我们（当时和alicia和tuotuo商量的时候想带麻婆豆腐的，结果我们都懒的到中超去买豆腐。。。）带了饭，还有迟到了1个小时的chris带来了炸香蕉，超油，还是冷的（我本来以为他会带薯条的，真的不知道美国的特色是什么），好吧，一会就被法国学生扫荡光了。本来很期待的buffet，估计他们是都指望国际学生带东西的，结果是。。。其他国家学生都没有带吃的来，好吧，结果就是，等我们的东西都分光了后，大家都饥肠辘辘，喝了3杯鸡尾酒（很好喝，基本就是果汁），这个是昨天soirée的主食了。哎，60校庆哎，竟然学校都不弄个像样的buffet,太差了，呵呵，上外绝对不会做那么“没面子”的事的，哈，这边人，疯是第一位的，才不管什么面子不面子的事呢。

估计圣诞过不了white x'mas了，所以，待会继续欣赏雪景，然后，继续travailler