7: 润滑油基础知识：制动液详解
BRAKE FLUID IS YET ANOTHER FLUID THAT YOUR VEHICLE COULD NOT DO WITHOUT FOR A MINUTE! READ ON TO UNDERSTAND WHY IT’S SO IMPORTANT, AND WHAT TO REMEMBER WHEN CHOOSING AND/OR CHANGING BRAKE FLUID.
制动液是汽车不可或缺的另一种车用液。继续阅读，了解其重要性以及选择和/或更换制动液时的注意事项。
We’re happy to show you around the world of automotive fluids in our ‘Basics of lubricants’ series. Today, we’re zooming in on brake fluid. Read on and become an instant expert!
我们很高兴在我们的“润滑油基础知识”系列篇中为您介绍世界各地的车用液。今天我们着重介绍制动液。继续阅读，秒变专家！
Why do you need brake fluid anyway?
为何需要制动液？
Your brakes keep you alive every day out on the road, and brake fluid is vital to the performance of both your braking and clutch systems. This is true whether you drive an on- or off-road vehicle, a car or a van, a motorcycle or a truck.
汽车刹车确保每日的道路安全，制动液对于制动和离合器系统的性能至关重要。这适用于在路机动车或越野车、汽车或面包车、摩托车或卡车。
Why it’s important to keep a good eye on the state of your brake fluid
密切关注制动液状态的重要性
Like any fluid in your vehicle, your brake fluid slowly becomes contaminated over time:
- Moisture and air contamination can creep in through weak seals or during routine maintenance.
- The fluid in your caliper or wheel cylinder may cook off from the high temperatures of braking.
- Hoses or lines may erode, adding foreign material to the fluid.
和任何车用液体一样，制动液也会在使用过程中逐渐受到污染：
- 如果密封不严，或在日常维护中，都会逐渐受到水分和空气污染。
- 卡钳或刹车分泵中的制动液可能会因为制动的高温而烤燃。
- 软管或管线可能会受到侵蚀，给制动液带来异物。
A reduction in responsiveness or even brake failure are the less desirable outcomes of this contamination.
此类污染会导致响应性降低，甚至刹车失效。
One of the most common contaminants of braking fluid are ‘air pockets‘. During maintenance a mechanic should ‘bleed’ your brakes, meaning that he flushes out all air pockets trapped in the brake system. If not done properly, brake fluid can suffer from ‘air contamination‘. Aging seals or other leaking components enable air to sneak in, leaving you with a spongy feeling when pressing down on the brake pedal.
制动液最常见的污染物之一是“气穴”。汽车保养时，机械师应该给刹车“放气”，意思就是要冲掉制动系统中的所有气穴。如果操作不当，制动液会受到“空气污染”。老化密封件或其他泄漏部件会让空气潜入，使得踩下刹车踏板时会有海绵般的感觉。
Contamination with moisture also undermines your brakes’ performance. Brake fluids are designed to absorb moisture, preventing loose water in the system from eroding components. But the more moisture your brake fluid absorbs, the lower its boiling point becomes. As a result the brake fluid van evaporate and form air pockets, leading again to a spongy brake pedal.
水分污染也会破坏刹车的性能。制动液在作用在于吸收水分、防止系统中自由流动的水侵蚀组件。但您的制动液吸收的水分越多，其沸点就越低。其结果是，制动液蒸发并形成气穴，再次导致刹车踏板海绵般的感觉。
What do the classifications of brake fluid mean?
制动液的分类是什么含义？
The U.S. Department of Transportation (DOT) sorts brake fluids into a series of classifications: DOT ¾, DOT 5 and DOT 5.1 are the most used categories these days. DOT ¾ and DOT 5.1 are ‘hygroscopic,’ meaning that they absorb airborne moisture. DOT 5 has a silicone base and is not hygroscopic.
美国运输部（DOT）将制动液分为各种类别：DOT ¾、DOT 5和DOT 5.1是目前最常用的类别。DOT¾和DOT 5.1“吸湿”，即可以吸收空气中的水分。DOT 5具有硅基，不吸湿。
Brake fluids are classified first and foremost by their boiling points. Because the brake pads create enormous friction when they press against the drum or disk, your brakes experience very high temperatures. If the fluid does hit its boiling point, it evaporates and becomes compressible, meaning that your hydraulics will stop functioning properly.
最先，制动液按照沸点分类。因为制动垫在压在鼓式刹车器或盘式刹车器上时会产生巨大的摩擦力，所以制动器会达到非常高的温度。如果制动液达到沸点后，它会蒸发，就变得可以压缩，造成液压系统无法正常运行。
The DOT measures both “dry” boiling point (uncontaminated fluid straight from the container) and “wet” boiling point (the fluid after it’s absorbed some water).
DOT测量“干”沸点（直接来自容器中未污染的液体）和“湿”沸点（吸收一些水后的液体）。
The next important property is the brake fluid’s viscosity (or thickness). All brake fluids must meet SAE specifications at minus 40 degrees C and 100 degrees C. Beyond this requirement, minimum and maximum viscosities vary between the classifications.
制动液的下一个重要特性是粘度（即稠密度）。所有制动液必须符合零下40摄氏度和100摄氏度的SAE规格。此外，各类别之间的最小和最大粘度各有不同。
How to choose a brake fluid for purchase
购买时如何选择制动液
First, you’ll need to choose what classification of brake fluid to buy. Don’t waste a lot of time comparing specs—the best guide is just to stick with whatever’s already in your system. It depends on your vehicle, but a higher classification of brake fluid won’t necessarily give you better performance.
首先要选择的是制动液的类别。请勿在规格上浪费太多时间，最好的方法是按照您的系统已经采用的类别。高类别的制动液并不一定会有更好的性能，这取决于您的车辆类型。
After you’ve made your selection, determine how much you need. Don’t fall for the false economy of buying a larger bottle, planning to use some of it later. In reality, this remainder will end up contaminated by airborne moisture, and you won’t want to use it for top-offs.
选好类别后，再确定需要的量。请勿为了省钱，购买大瓶制动液，以后再慢慢使用。实际操作中，剩下的部分最终会受到空气中的水分污染而无法再用。
Get rid of these contaminated leftovers—or better yet, don’t buy more than you need in the first place. To make this more convenient, Wolf offers brake fluid in a variety of sizes, including 250 ml, over 500 ml, and 1 L.
丢掉这些受到污染的剩余液，或最好一开始就不要买超过需求的量。为此，Wolf配备了250毫升、500毫升以上和1升等多种规格的制动液。
Other concerns when buying brake fluid
购买制动液时要考虑的其他问题
When buying, you’ll want to make sure the package is airtight, with its foil intact. If the seals are broken, this means that the fluid has already been exposed to air and moisture, reducing its effectiveness and lifespan.
购买时，需要确保包装密封，箔片完好。如果密封破损，就表示制动液已经暴露在空气和水分中，其有效性和使用寿命都会减少。
Finally, keep in mind that you should never “mix and match” classifications of brake fluid. All fluids that fulfil DOT requirements are compatible, but mixing a DOT 3/4 fluid with a DOT5.1 fluid will give your fluid a new, unknown chemical composition. This mixture may no longer be compatible with all your system’s components. If you decide to switch fluid classifications, be sure to cleanse your system before adding the new fluid.
最后要记住的是，切勿“混合并匹配”各种类别的制动液。满足DOT要求的所有制动液都可相容，但将DOT 3/4制动液与DOT5.1制动液混合将产生新的未知化学成分。这种混合不再与所有系统部件相容。如果您决定更换制动液类别，请确保彻底清洁系统后再加入新的制动液。
Wolf offers top-quality brake fluids for every need—click through to our website for details!
Wolf有着满足各种需求的优质制动液，详情请登录我们的网站！
Summary
- Brake fluid is vital to the performance of both your braking and clutch systems.
- Like any fluid in your vehicle, your brake fluid slowly becomes contaminated over time and needs regular maintenance.
- The U.S. Department of Transportation regulates brake fluid classifications by boiling point, viscosity, and other properties.
- To determine what classification to buy, look at what’s already in your system.
- Don’t fall for the false economy of buying a larger bottle, you won’t want to use leftovers for top-offs.
- Never mix different classifications.
总结
- 制动液对于汽车的制动和离合器系统的性能至关重要。
- 和任何车用液一样，制动液也会在使用过程中逐渐受到污染，需要定期保养。
- 美国运输部按照沸点、粘度和其他特性来规定制动液的类别。
- 请采用您的汽车系统中已经在用的类别。
- 请勿为了省钱而购买大瓶的制动液，剩下的部分最终会无法再用。
- 切勿将不同类别的制动液混用。
