The application background of toothed clamp differential in road rollers

I. Source of the Problem

At present, the gearboxes used in our company's "J" series and static roller series are independently processed and manufactured from the products of the Japanese Sakai Company in the 1970s. The differential is of planetary bevel gear structure and is equipped with a manual differential interlock device. The gearboxes of the same structure are used in rollers ranging from 10 tons to 21 tons. For decades, this transmission has made tremendous contributions to the company's product development, and its reliability has also been verified.

In recent years, through continuous improvement, the faults of the transmission itself have been relatively few, but other faults caused by improper operation have been more frequent, especially the accidents of J series side transmission damage (including gear breakage, transmission shaft breakage, etc.) have occurred frequently. The main reason is that the manual differential interlock device has been in a locked state for a long time, that is, forced steering is caused when the differential does not have a differential effect. When the road conditions are poor, that is, the adhesion coefficient of one wheel decreases and the driving force is lost, the differential interlock device can be used to interlock the wheels on both sides, which is conducive to the machine getting out of the "predicament". This road condition may be a muddy road or a slope with poor road conditions. In addition, this function is not frequently used, and its effect during use still needs to be proven (such as whether the strength design of the side drive has fully considered this working condition, the overload capacity of the transmission system, and the difference between the design and the actual situation, etc.).

Ii. Cause Analysis

The differential interlock device has been in a locked state for a long time, which is the direct and main cause of a series of faults.

2. The variation range of the control lever of the differential interlock device is not large, making it difficult for the driver to identify.

3. The instructions on the dashboard regarding how to operate properly are unclear.

4. The processing accuracy of the parts is not high, especially at the positioning positions of the steel balls, which leads to increased resistance and makes it inconvenient to operate, that is, the hand feel is not strong.

5. The instruction manual does not provide sufficient warnings about possible malfunctions caused by misoperation of the differential interlock device.

Iii. Solutions

1. Cancel the differential interlock device

Advantages: ① Completely eliminate a series of faults that may be caused by misoperation of the differential interlock device.

② Relevant parts have been removed.

Disadvantages: ① The differential interlock device is one of the functions of the entire machine. Without this function, it does not meet the mechanical transmission performance requirements of general vehicles.

② There are potential safety hazards under special working conditions. For instance, when climbing slopes with poor road conditions, especially in mountainous areas, the differential interlock system is the guarantee of climbing ability. Otherwise, in the event of a safety accident, our factory will have to pay a huge price for the damage to product quality and factory reputation.

③ Adjust the user manual and parts catalogue accordingly.

2. Remove the control handle

Treatment method: ① Strictly control the processing quality of parts.

② Refine the operation indicators, engrave the instructions for reverse and reverse operation, gear position, differential operation, etc. on the handle ball, making the operation requirements clear at a glance.

③ Add warning signs to the dashboard.

④ The manual emphasizes the serious consequences of misoperation and elaborates in detail: in general plain areas, when it is necessary to lock the differential interlock device, how to operate to achieve it, and the control handle should be removed in time after use. In mountainous areas or on slopes with poor road conditions, differential interlocking devices must be used, and how to use differential interlocking devices to avoid safety accidents.

Advantages: ① It maintains the differential interlock function of the entire machine.

② It can ensure that no related faults occur in general plain areas, and can minimize the occurrence of related faults in mountainous areas or on slopes with poor road conditions as much as possible.

③ Just adjust the content of the user manual accordingly.

Disadvantages: ① It is necessary to control the departure status (remove the control handle).

② Adjust the detailed description of the locking differential interlock device in the user manual accordingly.

③ Overseas service personnel mostly adopt this method, but only after quality problems occur.

3. Switch to an imported toothed differential

Treatment method: ① Process the housing of the new differential.

② Replace the imported toothed differential.

Advantages: ① The toothed differential has no differential interlock device. According to the changes in ground load, the differential and differential interlock functions can be automatically switched, and there is no control mechanism. Completely eliminating a series of faults that may be caused by misoperation of the differential interlock device and removing related parts at the same time can reduce costs.

② The existing planetary bevel gear differential has a large structural size, a complex operating mechanism, a relatively large operating force, many factors affecting the difficulty of operation, is prone to misoperation, and has poor maintainability. At present, all advanced drive axles in the world adopt toothed clamp type differentials, which is the development direction of differentials.

③ The imported caliper differential has been tested on our company's drive axles (originally equipped with caliper differentials) and is being supplied in small quantities. The procurement channels are unobstructed.

④ The adoption of a toothless differential for the entire machine without differential control represents a technological advancement, which enhances both the performance and reputation of the main engine.

Disadvantages: ① The cost of a single roller increases by approximately 2,000 yuan.

4. Conclusion

Based on the above analysis, neither of the first two methods is the fundamental solution to the problem and cannot completely eliminate the hidden danger. Only by adopting a toothed differential is the correct solution, and the technical verification of this solution has been affirmed. The time for batch adoption depends on the matching situation of related components. Cost is a comprehensive factor. It should be evaluated as a whole. Although the production cost has increased, the service cost has decreased. The total cost is not necessarily high. At the same time, it has brought about an improvement in reputation and brand promotion. Therefore, the application scenario of the tooth clamp differential in the roller is bright.