Application of Wet Multi-disc Brakes on Forklifts

　1. Preface

       The brakes used in engineering vehicle products mainly include: shoe brakes, wet multi-disc brakes, and caliper disc brakes. Most 1-10t forklifts produced by domestic enterprises use shoe brakes; forklifts and stackers above 16t use wet multi-disc brakes; loaders often use caliper disc brakes (low configuration) and wet multi-disc brakes (high configuration).

       In recent years, wet multi-disc brakes have been widely used in the braking systems of construction machinery such as forklifts and loaders imported from abroad, such as DAEWOO from South Korea, CLARK and CATERPILLAR from the United States, VOLVO from Sweden, and KESSLER from Germany. Wet multi-disc brakes are commonly used in leading products. It has been proven through the use of various working conditions that wet multi-disc brakes have many features such as large braking torque, long service life, strong anti-fade and anti-pollution capabilities, and no need for repairs, thus winning wide popularity among users.

        Anhui Kaisha Industrial Equipment Manufacturing Co., Ltd. is a leading enterprise in the domestic forklift manufacturing industry. The company's technical center has been committed to the research and development of forklifts and their components. Now it has taken the lead in applying wet multi-disc brakes to three-fulcrum electric forklifts, 5-10t electric forklifts, 16-18t forklifts, 18-25t forklifts, 50 loaders and other engineering vehicles. The newly developed G series forklifts will also be selected. Equipped with wet multi-disc brakes.

    2. The structure, operating principle and characteristics of wet multi-disc brakes

       Wet multi-disc brakes are mainly composed of brake housing, brake piston, friction plate, oil seal and end plate. Several fixed and rolling brake friction plates are interlaced with each other and installed in a sealed brake housing filled with cooling oil. The fixed friction plates (pressing plates) are connected to the brake housing through external splines, and the rolling friction plates pass through The internal spline is connected to the wheel hub and rotates with the wheel hub. When the oil from the brake valve enters the brake, the brake piston compresses the brake friction plate of the interlacing device, causing the rotating friction plate to be decelerated by the friction force until it stops rolling, achieving the purpose of braking.

       From the above structure and principle analysis, it can be seen that wet multi-disc brakes have the following characteristics:

        1）. The brake friction plate is operated in a sealed oil bath. The porous fiber surfaces on both sides of the friction plate can ensure that there is a thin film of oil that always separates the friction plate and the pressure plate, preventing the friction plate and the pressure plate from being in direct contact, and can prevent the friction plate from being in direct contact with the pressure plate. The occurrence of conflicts minimizes wear between pieces. This type of brake has stable operating performance, does not require frequent adjustments, and has a long service life, which is generally 3-5 times that of dry brakes. Its performance will not decline after more than three years of use.

        2）. Since the wet multi-disc brake is fully enclosed, components such as the pressing plate, friction plate, end plate and brake piston are all installed in the brake housing, which can be protected from external moisture, dust, impurities, etc. In addition, the brake uses a brake hydraulic pump. When the hydraulic oil enters the brake cylinder, the force of the piston pushing the fixed disc and the friction disc is evenly distributed, and the hydraulic pressure is linearly related to the braking force formed. Therefore, the braking is quick and smooth, the braking performance is stable, and it has high safety.

        3）. The wet multi-disc brake is hydraulically driven and cooled by oil circulation. It has excellent heat dissipation performance, reduces repair and maintenance, and extends the service life. The cooling method can be selected from self-cooling or forced cooling according to the braking intensity. Self-cooling brakes have no seal between the support shaft and the wheel hub. The lubricating oil of the lubricating differential and planetary wheel reducer can flow directly to the brake to achieve the effect of cooling the brake disc at the same time, such as three-pivot electric forklifts, 5-7t Forklifts and 50 loaders use self-cooling circulation cooling. Forced cooling is to circulate the coolant in the brake through the forklift hydraulic system and force cooling outside the brake. For example, 16-18t forklifts and 18-25t stackers use forced hydraulic oil circulation cooling. Even if the forklift operates at sustained high speed, high load, and frequent braking, the braking effect will not be reduced due to heat.

        4）. Wet multi-disc brakes adopt a multi-disc structure and have a large annular working area. They can obtain a large braking torque under a small lining pressure, while the pressure on the components is reduced, and the specific pressure of the friction plate unit is small. The braking torque can be adjusted by changing the number of conflict pairs, making it easy to achieve serialization and standardization of conflict pairs.

       5）. Compared with dry brakes, the initial cost of wet multi-disc brakes is slightly higher, but because the brakes have the advantages of no wear, no need for frequent maintenance, and long-term stable performance, they can produce low maintenance costs and ensure high productivity. . According to estimates, based on the periodic maintenance fees and routine repair fees incurred by dry brakes, as well as the cost of parking losses and other costs, the above-mentioned additional investment can generally be recovered in about half a year of operation. It can be seen that a forklift that remains in production can transform the time and cost losses caused by failures and repairs into higher economic benefits.