The role of hydraulic fluid in a hydraulic clutch system

Hydraulic clutch systems require hydraulic fluid to ensure proper operation. The hydraulic fluid plays a vital role in the system and its main functions include:

1. Transmitting pressure:

   - When you depress the clutch pedal, the hydraulic fluid transmits pressure through a series of hydraulic lines and the clutch master cylinder to the clutch slave cylinder, which pushes the clutch pressure plate and the clutch disc (flywheel) apart or together.

2. Lubrication:

   - Hydraulic oil lubricates the various moving parts within the system, reducing wear and prolonging the life of the parts.

3. Cooling:

   - During clutch operation, hydraulic fluid can help dissipate heat and prevent the system from overheating.

4. Protection from contamination and corrosion:

   - Hydraulic oil can form a protective film to prevent corrosion of metal parts and can carry away contaminants to keep the system clean.

 Hydraulic Fluid Selection

Hydraulic fluids are usually mineral or synthetic:

- Mineral Oil:

  - Crude oil extracted from underground deposits, has the advantages of good fire-fighting performance, cheap and so on.

  - But not for some high temperature and pressure, high speed, high precision and other occasions.

- Synthetic oil:

  - Artificial synthetic oil, has a long service life, good stability, good extreme pressure performance, good low temperature performance.

  - But the price is higher than mineral oil.

In the choice of hydraulic oil, according to the working conditions of the hydraulic system, the use of the environment, performance and other factors for comprehensive consideration, choose the appropriate type of hydraulic oil and brand.

 Hydraulic oil replacement cycle

The replacement cycle of hydraulic oil varies depending on a variety of factors, including the type of equipment, operating conditions, and the type of hydraulic oil. The following are some common guidelines for hydraulic fluid change intervals:

 General Hydraulic Fluid Replacement Intervals

1. Normal machinery:

   - The first hydraulic fluid change is usually after six months of use, after which a yearly change is recommended.

   - If the equipment is not used frequently, the replacement time can be delayed appropriately.

2. Normal hydraulic oil:

   - The oil change cycle is generally recommended for 1 year.

3. synthetic hydraulic oil:

   - Due to its superior performance, the oil change cycle can be longer, recommended for 3 years.

 Factors affecting the replacement cycle of hydraulic oil

1. temperature:

   - High temperature environment will accelerate the oxidation process of hydraulic oil, shorten its service life. 

2. Humidity:

   - High humidity environment may cause the hydraulic fluid to absorb water, leading to emulsification and corrosion, accelerating its deterioration.

3. Pollution:

   - Contaminants such as dust, particles and wear particles can accelerate the rate of wear and oxidation of hydraulic fluids.

4. load and pressure:

   - High loads and high pressure working conditions will make the hydraulic fluid to withstand greater stress, accelerate its aging and deterioration.

5. operating time:

   - The longer the continuous running time of the equipment, the shorter the service life of the hydraulic fluid.

6. Base oil quality and additive performance:

   - High-quality base oil and effective additives can extend the service life of hydraulic oil.

 Replacement cycle to determine the method

1. empirical method:

   - Maintenance personnel with experience, based on visual inspection of some of the oil routine state changes (such as oil black, odour, become milky white, etc.) to decide whether to change the oil.

2. Regular oil change method:

   - According to the environmental conditions of the site where the equipment, working conditions and the oil used in the oil change cycle, due to be replaced. This method is very suitable for hydraulic equipment more enterprises. 

3. Sampling and testing method:

   - Regular sampling and testing of hydraulic machines in the fluid, the determination of the necessary items (such as viscosity, acid value, moisture, particle size and content and corrosion, etc.) and indicators, according to the actual measured value of the oil quality and the provisions of the oil deterioration standards for comparison, to determine whether the fluid needs to be replaced.

   - The sampling time is usually one week before the oil change cycle, and for critical equipment such as TBM full section roadheader, sampling and testing should be carried out every 500 hours.

 Precautions for replacing hydraulic oil

1. When replacing hydraulic oil:

   - It should be ensured that the new oil is of the same type as the old one, and avoid mixing hydraulic oils of different brands and types.

2. Replacement process:

   - Pay attention to cleaning and sealing to avoid contaminants entering the hydraulic system. 

3. After replacement:

   - The performance and sealing of the hydraulic system should be checked to ensure that the equipment works properly.

 How to judge whether the clutch needs to replace the hydraulic oil

To judge whether the clutch system needs to replace the hydraulic oil, you can consider the following aspects:

1. Check the maintenance intervals:

   - Check the vehicle's owner's manual for the manufacturer's recommended replacement intervals. Typically, the recommended replacement interval for brake fluid (for hydraulic clutch systems) is 2 years or 40,000 kilometres, but this may vary by model and manufacturer.

2. Observe the colour and smell:

   - Check the colour and smell of the hydraulic fluid. Fresh brake fluid is usually clear or light yellow in colour. If the fluid becomes dark, cloudy or has a distinct burnt smell, this may be a sign of aging or contamination and needs to be replaced.

3. Decreased performance:

   - If you notice that the clutch pedal feels softer and less responsive than before, or if you feel that the clutch does not engage smoothly when shifting gears, this may be a sign that there is insufficient fluid pressure in the hydraulic system, and it is possible that the fluid needs to be replaced.

4. Leak check:

   - Check for leaks in the clutch system. Leaks can cause a reduction in fluid, affecting system pressure, and may also contaminate the fluid. If a leak is found, the leak needs to be repaired while replacing the fluid.

5. Abnormal operation:

   - If, while driving, you notice a sluggish response from the clutch, such as needing to press deeper to shift gears, or an unusual sensation when the clutch engages, this could be a sign of a fluid problem or internal wear in the system.

6. Regular testing:

   - Some professional repair shops will perform a brake fluid water content test. When brake fluid absorbs water, the boiling point will be lowered, affecting performance at high temperatures, which is also a basis for replacement.

7. Maintenance habits:

   - Even if there are no obvious problems, it is important to follow regular maintenance habits. Regular hydraulic fluid changes can prevent system failures due to fluid deterioration.

 Summing up

In summary, hydraulic fluid is indeed required in hydraulic clutch systems and the selection of the right fluid and regular maintenance and replacement are essential to ensure that hydraulic clutches work properly. Regular maintenance and testing, control of the working environment, the correct use and storage of hydraulic fluid can effectively extend its service life, reduce the maintenance costs of the equipment, improve the reliability and operational efficiency of the equipment.