The Influence of Brake Fluid on the Braking Performance of Loaders and Discussion

I. Introduction

In recent years, the faults of the braking system of loaders have been on the rise, especially a series of problems such as brake failure, temperature rise of the braking system, and oil leakage from the vent holes of the brake pump. Currently, the service braking systems of domestic loaders almost all adopt air-top oil caliper disc brakes, and the selection of braking components is largely the same as that of automobiles. The causes and influencing factors of the failure of the braking system of a loader are multi-faceted, such as the damage of braking components leading to brake failure. In recent years, the braking system of loaders has shown an upward trend. The author believes that the decline in the quality of brake fluid and brake friction pads is also one of the influencing factors. The following is a brief introduction to the influence of brake fluid on the braking performance of wheel loaders.

Ii. Performance Requirements for Brake Fluid in Loaders

(1) Good viscosity-temperature performance and low-temperature performance

Loaders often operate in harsh working environments such as mountainous areas and mines. Therefore, the working mode of loaders requires them to frequently move forward and backward in each working cycle. The brake friction plates remain in a braking state for a long time. During the braking process, due to frictional heat generation, the temperature of the friction plates can reach up to 250℃. Part of its heat is transferred to the brake fluid, causing its working temperature to reach 70℃ to 90℃. In mountainous and other environments where frequent braking is required, its working temperature can reach 110℃, and sometimes even as high as 150℃. However, in winter in regions like Northeast and Northwest China, the temperature of the brake fluid can drop below -40℃. Therefore, the brake fluid is required to have good viscosity-temperature performance and low-temperature fluidity. Suitable high-temperature viscosity, low freezing point and low-temperature viscosity.

(2) Appropriate lubricity

To ensure that the brake cylinder and rubber bowl can slide well, the brake fluid is required to have appropriate lubricity.

(3) Ensure safe and reliable braking without air resistance

When a loader is in motion, frequent braking generates a large amount of frictional heat, causing the temperature of the braking system to rise. If brake fluid with a low boiling point and easy evaporation is used, at high temperatures, due to the evaporation of the brake fluid, the local braking system pipes will be filled with vapor, resulting in vapor lock and causing brake failure. Therefore, brake fluid is required to have a high boiling point and low volatility to avoid reducing the occurrence of vapor lock.

(4) Good corrosion resistance

Brake fluid should have good anti-corrosion properties for various metal parts of the brake.

(5) Good chemical stability

Brake fluid is used for a long time under the effect of high humidity. Therefore, it is required that the brake fluid does not undergo thermal decomposition and overlap, which would increase the viscosity of the oil, nor is it allowed to form sludge deposits.

(6) Good compatibility with rubber

In the braking system, there are many rubber seals and cups, etc., which are used to keep the braking system completely sealed. Therefore, the brake fluid should have good compatibility with rubber seals to prevent the rubber seals and cups from expanding and having their mechanical strength reduced due to incompatibility with the fluid.