Hydraulic brake and its circuit. Hydraulic brakes on a bicycle

Brakes, both mechanical and hydraulic, the vector of action is just one - stop the vehicle. But there is a whole set of questions concerning both types of schemes. It is worth considering the hydraulic brake in more detail. Its main difference from the mechanical one is that a hydraulic line is used to drive the shoe, not ropes. In the variant with hydraulics, the connection of the brake mechanism to the handles takes place directly.

Principle of operation

To understand how the hydraulic brake works, it is necessary to consider its device. To fill the waterline, a special oil or brake fluid is used, which is under insignificant pressure. Pressing a special handle leads to the displacement of fluid from the hydraulic system, as a result of which it exerts pressure on the working cylinder mounted on the fork or bicycle frame. As a result, the brake pads and the piston are activated, which results in locking the wheel.

It's pretty simple. The hydraulic brake circuit provides a visual representation of the operation of the entire described system. Working with such a device requires understanding that the brake fluid is characterized by extreme toxicity, which often causes severe poisoning. In addition, it can have a detrimental effect on plastic parts and paintwork.

Advantages and disadvantages of hydraulics

The wide distribution of such a brake system can be explained by the accuracy of the dosing and the high speed of the reaction of the mechanism on the pressing of the handle. However, the advantages do not end there, but they became the decisive factor for many athletes in the issue of access to hydraulics.

Another important point is the excellent endurance, which has hydraulic disc brakes. The accuracy of operation is not less important. The system proved to be reliable for many years of operation in cars. Proper care allows you to make sure that the hydraulic brake installed on the bike will be much more reliable in comparison with the mechanical one. A sharp sense of the strength of the dosage makes it possible to use the brakes as precisely as possible. It's just necessary in extreme sports.

Among the shortcomings of the hydraulic system, there are several basic ones. The cost of such a system is significantly higher in comparison with the mechanical, so the price of a bicycle with hydraulics will be significant. Such a device is a technological and very complex unit that requires the maintenance of skills and a clear understanding of the design features. Not every biker has the necessary knowledge for self-disassembly and repair of the hydraulic brake.

Careful attitude to themselves requires such components as brake hoses and pipes. These are very vulnerable places that have a direct impact on the functioning of the entire system. Hydraulic brakes on a bicycle can be picky to the quality of oil or brake fluid, so the pumping should be done after a thoughtful choice is made. Quite often they are used in conjunction with traditional disk. It is necessary to say a little about them.

Types of hydraulic disc brakes

The difference between the disc brake and the rim is that the braking is carried out by clamping the disc, which is fixed to the hub quite rigidly with special pads fixed on the back of the frame and in front on the forks of the fork. The master cylinder uses a different design, so the hydraulic brake can belong to one of the following types: single-piston, two-piston with floating or opposing pistons, multi-piston. The third type is mainly used. You can meet models belonging to the first species, but because of certain shortcomings they were almost completely replaced by the second and third types. Complex systems with a lot of pistons are used for downhill, where the decisive role is assigned to capacity, rather than simplicity of design.

Distinctive characteristics

If we consider the hydraulic drive of the brakes, then it is appropriate to note the possibility of using oil or a special liquid. Each of the options has both shortcomings and dignity, but so far there is no unequivocal opinion on this matter. The caliper is monolithic, due to which the design becomes light and rigid, and composite, characterized by a lower price, but greater complexity in terms of maintenance.

The disc hydraulic brake is reliable, but it is difficult to repair it in the field. True, it breaks down in extremely rare cases. There are a number of problems associated with the fact that the disc hydraulics has a very small gap between the shoes, and in the presence of strong contaminants they wear out at times more quickly. However, in this case, the mechanic can not boast at least some advantage, as the damaged pads can not be adjusted on the go, and in the case of hydraulics, this is done automatically during wear.

Disc brakes are significantly more expensive than the rim, their load on the bushing during braking is greatly increased, although this issue can be called controversial. It is not necessary to delve deeper into this topic, it is better to tell about the manufacturers represented in the market of hydraulic brakes.

Brand overview

Despite the fact that there are a lot of types of brake systems, on the bikes of the middle level, the hydraulic brake is quite common nowadays. With the growth of their popularity, one can note a noticeable drop in the price. Therefore, it is quite possible that you will decide to retrofit your bicycle under the hydraulic brake system. There are many examples of this, but we will give just a few.

One of the manufacturers is the company Shimano. Hydraulic brakes of this brand are presented in several lines. The most recent was Deore. Its characteristic is the stable operation of the master cylinder, convenient and pleasant to use the handle. A cyclist can get a real pleasure from how the whole system is clearly working and obediently behaving. The picture is slightly overshadowed by the rattling of the brake handle itself. The new collection is represented by two variants of fastening of the rotor: bolt and spike. In one set comes two types of shoes - metallized and rubberized. Wear of the latter proceeds as quickly as possible. In general, this hydraulic brake of superior quality, which costs money spent on its purchase, namely, $ 50.

CLIM 8 CLARK`S brakes are characterized by the fact that buying a device at the price of a single-cylinder brake, you get a full multi-cylinder device. However, everyone knows that miracles do not happen, that's why the design of pens is a little alarming, but this parameter finds its fans. But the hydraulic hoses were reinforced with metal and Kevlar.

The most interesting design, which has six cylinders, is available from the caliper. This system is characterized by such a disadvantage as an increase in mass. In addition, during the installation it is required to fit the pads to the discs as thoroughly as possible.

The hydraulic brake is characterized by the fact that the reviews about it can be quite diverse. It is often said that such a system is rather fastidious in terms of service. However, this statement can be called controversial. This is not difficult at all, and you can see for yourself. In the maintenance of the brake system, the most difficult job is to pump it. Almost every biker, who uses hydraulics, encounters such a problem. You can estimate how difficult this procedure is.

Symptoms of a malfunction

The very first sign that bicycle brakes are faulty is the fact of their independent braking. This can be explained by the fact that there was a small amount of air inside the system. This could happen because of the fall of the bicycle, with the opening of the hydraulic circuit, as well as at a low level of the brake fluid in the tank.

Since the property of air to compress significantly distinguishes it from liquids, when it enters the system it can trigger as a gas spring. As a result, a fluid pressure is created, which activates the brakes. The rear hydraulic brake can engage in such amateur performance in the event that the working piston begins to jam. This can be caused by the fact that water enters the hydraulic system. Another point that should alert you, is the loss of the elasticity of the brake handle in comparison with the early period of operation. And if the hydraulics does not react at all to your bicycle stop command, then there will be only one solution: immediate replacement of the entire system.

Troubleshooting and repair

To understand what exactly happened to the bicycle braking system, it is necessary to conduct several experiments. First of all, you need to remove the wheel, which marks the problem. Next, you will need to make some efforts to clean the brake machine from dirt, which is easiest to do with a toothbrush. The main task in this case is to remove the pads.

After opening access to the working pistons, you must press them with a screwdriver, and then gently press the brake knob. Both pistons must move forward. If there is jamming of one of them, then a repair kit is required to eliminate the existing malfunction. The piston system must be carefully inspected for various leaks. In the case of their presence, we can speak of a strong deterioration of a group of cylinders. Now you will need to replace the pistons or special O-rings on them. In the end, you need to carefully inspect the entire hydraulic line. A good sign is the absence on it of kinks, dents and damages of a different kind. If there is one, replace the entire waterline.

Why do I need to be pumped?

If you press the handle of the brake, and it leaves before the flu, that is, its stroke is too large, but the pads do not move or get to the brake disc, then you can draw conclusions about the need for pumping. A similar situation is observed in the case when the lever is too easy to move when pressed or completely fails. When the handle is pressed sharply, and after the system has been triggered, it does not return to its original position, it is also required to pump the hydraulic brakes onto the bicycle.

In these cases, the cause of the system's failure was the air that was inside. First of all, it is required to find the place through which the transmission is carried out. It should be noted that this may be preceded by damage to the hydraulic fittings, weakening of the bleed valve on the cylinder, boiling of the liquid, which is due to overheating. When the entire system is checked for fluid leakage, it will be possible to start repairing it.

If you need to pump a hydraulic brake, the physics in this case says about the need to do this on a horizontal level surface. Pads should be diluted so that they do not reach the disc. Then it is required to unscrew the master cylinder, then fix it horizontally. Each system features pumping can vary, so you should use the instruction in which everything is detailed.

Final works

Then it is required to put the cambric on the bolt, and then to immerse it in the container to collect the remaining liquid. After this, it is necessary to unscrew the cap of the expansion tank and fill it to the maximum level with a liquid. It is necessary to press the brake several times, but it is recommended to do this smoothly and slowly. Pressing is required until a tightness appears. Further, while holding the handle, it is necessary to unscrew the bleeding bolt together with the kembrikom and add the liquid to the expansion tank. Carry out this procedure is recommended until the handle does not achieve the required level of rigidity. After that, you can tighten the expansion tank, and then remove all tools. Everything is ready, now the brakes are fully pumped.

conclusions

As you can see, rumors about the complexity of pumping are overly exaggerated. The hydraulic brake system is characterized by the fact that it has more advantages than disadvantages. A real biker is not so much important principle of the operation of some mechanism, and the very fact that he has the ability to move freely in space. And the disc hydraulic brakes on the bike allow it that.

Successful trips to you!