How to extend the service life of construction machinery

For the same model of construction machinery, due to differences in design level, manufacturing quality, usage environment, as well as the technical and management levels of the user and maintenance units, their service life can vary significantly. Therefore, throughout the entire process of research, design, manufacture, installation, operation, maintenance and repair of construction machinery, there is a responsibility to contribute to extending the service life of the machinery.

In terms of design

Excellent design is the primary link in extending the service life of machinery. Japan proposed the concept of "design-based business", which has made Japanese products durable and sold them worldwide. At the railway construction sites in our country, many of the main equipment are Japanese products. Seats and control consoles designed according to ergonomics, environmentally friendly low-noise engines, and streamlined cabs that are pleasing to the eye are all very popular among users. To introduce the design materials of Japanese manufacturers such as Hitachi Construction Machinery, Caterpillar - Mitsubishi, Komatsu, and Kobe Steel, the main design method for extending the service life of machinery is to implement feasible design and maintenance design.

The new Caterpillar - Mitsubishi Corporation of Japan has accurately analyzed the stress of force-bearing components such as bulldozers at construction sites by applying load analysis methods, and proposed a design to extend the service life of machine parts (longevity design), namely: ① Reducing surface pressure (contact stress on the surface of machine parts), such as using helical gears instead of involute gears to increase the overlap coefficient. ② Disperse the load. For instance, if a triangular belt traveling system is used instead of the commonly seen track traveling system, and the drive wheels are moved from the conventional contact type to the top of the triangle, disengaging from the ground, the impact load and working load that the drive wheels bear will be significantly reduced. ③ Reduce heat, such as by using wet clutches, wet brakes, etc., to minimize frictional heat. Striving to improve the maintainability of machinery during design is a powerful measure to extend its service life. The definition of maintainability is: "The difficulty or nature of repairing systems, equipment, or components." The service life of a component or an entire machine is closely related to the quality of its maintainability. Japanese construction machinery manufacturers believe that if the machinery has good maintainability and is easy to repair, and can adopt "low-cost rapid repair", the machine parts can always be in good technical condition. Once a fault occurs, since it can be repaired at low cost and quickly, there is no need to replace new parts or new machines, which actually extends the service life of the machinery. Therefore, when designing new machines, efforts must be made to enhance their maintainability. The main principles are as follows: ① Simplify disassembly and assembly. Such as the use of OPS pipe joints (O-ring joint), separated track links, flip-type cabs or engine hoods, and hinged structures with adjustable clearance, etc. ② Component assembly. The components are designed as easy disassembly and assembly parts. For instance, the CAT D9L bulldozer, due to the adoption of a component assembly design, has reduced the component disassembly and assembly time by 60% to 75% compared to the CAT D9H bulldozer. ③ Centralized refueling. For instance, in the large bulldozers produced by Komatsu, the oil filling ports (oil filters) and pressure measurement points of components such as the transmission and torque converter are centrally arranged in one place. The driver can simultaneously fill oil and check the oil pressure of these components while standing on the ground, eliminating the fatigue of climbing up and down. This is conducive to ensuring that lubrication is carried out on schedule and preventing omissions. ④ Check the monitoring system. By applying electronic and micro technologies, the oil quantity, oil temperature, shaft temperature, water temperature, vibration and load are monitored to prevent faults before they occur. ⑤ Extend the lubrication cycle. If double filters are adopted to prevent the oil from aging easily; For the hinge parts of the rod system with light loads and infrequent movement, oil-impregnated bearings are adopted to achieve oil-free lubrication. Sealed and lubricated tracks and the like are adopted to reduce the aging and leakage of oil, which not only extends the lubrication cycle and reduces the amount of maintenance work, but also ensures that the machine parts are in a good lubrication state. ⑥ Generalization of vulnerable parts: For commonly used vulnerable parts, general-purpose parts should be adopted as much as possible to reduce spare parts reserves and facilitate the procurement of spare parts. ⑦ Complete random tools. When designing random tools, thorough consideration should be given. It is convenient for drivers to carry out daily maintenance and repair. ⑧ Minimize maintenance items as much as possible in the design and gradually achieve maintenance-free design.

Adopting new materials is an effective measure to extend the service life of machinery. In recent years, the development of materials science has been rapid, and a large number of new materials with high strength, wear resistance, vibration resistance and impact resistance have emerged continuously. When designing new machines, new materials that are suitable for mechanical properties and working conditions should be selected to extend their service life.

In terms of manufacturing

To enhance the quality of machinery and ensure its durability, each manufacturer has its own quality assurance system and testing methods. Some main machines and assemblies of construction machinery are of relatively good quality. However, the mechanical accessories produced by the external manufacturers are of poor quality, which leads to frequent malfunctions of the entire machine. For instance, there is a type of loader that only has the safety sealing ring of the main control valve being of substandard quality and needs to be replaced frequently, increasing the maintenance workload. Therefore, the main engine manufacturers should strictly follow the acceptance standards for outsourced parts. Unqualified outsourced parts are not allowed to be installed.

In terms of usage

To extend the service life of construction machinery, the "Two Fixed and Three Guaranteed" system (fixed personnel, fixed machines, guaranteed usage, guaranteed storage, and guaranteed maintenance) must be adhered to in terms of usage. Machinery operators should achieve "three understandings" (understanding structure, principle, and performance) and "Four abilities" (knowing how to use, maintain, inspect, and troubleshoot), and use the machinery correctly. Strictly enforce safety technical operation procedures, and implement target cost management for mechanical equipment. Link the economic benefits of operators with mechanical usage fees (such as fuel and electricity fees, maintenance fees, upkeep fees, tool fees, etc.), and strengthen the professional ethics education and training for mechanical management personnel. One often overlooked issue that needs to be particularly pointed out here is the impact of the environment on the use of machinery due to diesel. Most construction machinery operates outdoors, and the operation sites frequently change, so its performance is greatly affected by factors such as the temperature, chlorine pressure, pollution, road conditions and weather of the operation site. Many construction units have neglected the impact of environmental factors on the use of machinery and failed to take corresponding protective or adaptive measures, resulting in a decline in the performance of the machinery, a shortened service life, and even accidents. If effective measures are taken at the construction site, such as frequently keeping the construction access roads flat and timely maintenance; On rainy days, fill in the puddles on the sidewalks in time. On sunny days, water them frequently to reduce dust. When building construction access roads, reducing the slope and other factors in accordance with local conditions are all beneficial to extending the service life of machinery.

Regarding maintenance

Regular maintenance of machinery is the key to extending its service life. Railway construction units have many clear regulations on the maintenance of machinery. However, when the construction period is tight and the tasks are heavy, many construction units often neglect the maintenance work, believing that the machinery is running smoothly without any faults and there is no need to stop for maintenance. Because maintenance can eliminate mechanical hazards, if it is not maintained in time, it often leads to major malfunctions of mechanical equipment and even accidents. This not only increases maintenance costs but also delays the project schedule.

Maintenance aspect

Maintenance work is an important link in extending the service life of mechanical equipment. Adopting reasonable maintenance methods can effectively prolong the service life of construction machinery.

According to statistics from Japan, by adopting condition monitoring and following the maintenance methods of South Africa, annual maintenance costs can be reduced by 25% to 50%, the failure rate can be decreased by 75%, and the service life of machinery can be extended. The Inspection center of the Second Railway Bureau conducts condition inspections on large imported machinery at construction sites every year, achieving good results and reducing maintenance costs by 10% to 30%. The repair volume has decreased by 47%, the mechanical integrity rate has increased, and the service life has been extended.

The "low-cost rapid repair method" proposed by Japanese construction machinery manufacturers is also an effective way to extend the service life of machinery or parts. To implement this method, in addition to adopting maintainability design in mechanical design to enhance the maintainability of machinery, the following methods can also be used in maintenance practice: ① Parts replacement: Many parts on construction machinery, such as the track pins of bulldozers and excavators, and diesel cylinder liners, often bear unidirectional loads during operation, which leads to uneven wear. If the positions of the parts subject to balanced loads are replaced in a timely manner to balance their wear, their service life can be prolonged. A T-320 bulldozer was equipped with a Cummins NT-855 engine cylinder liner, which needed to be replaced every six months due to cavitation. Later, after the cylinder liner had been in operation for a period of time, it was installed by rotating 90º, which effectively extended its service life. ② Brush plating and adhesive repair: By applying the brush plating and adhesive repair process on the construction site, failed parts can also be repaired quickly and at low cost.

With the advancement of maintenance technology, a large number of advanced repair processes that can extend the service life of mechanical parts have emerged, such as wear-resistant surfacing, diamond-nickel coating spraying, magnetic electroplating, laser electroplating, etc. Due to limited conditions, the construction unit cannot use all of them, but it can cooperate with local large-scale production enterprises to rationally utilize the current repair technology to extend the service life of the machinery.

It is worth mentioning that the methods discussed above are all about extending the physical lifespan of machinery. In fact, the lifespan of machinery can be divided into economic lifespan and technical lifespan. Economic life refers to the most reasonable service period of machinery from an economic perspective. Specifically, it refers to the number of years during which the average annual usage cost of the machinery (consisting of the annual apportioned amount of machinery purchase cost and the annual operating cost of the machinery) can be minimized. Technical life is the most reasonable period of use of machinery from a technical analysis perspective. Specifically, it refers to the time from the beginning of the machinery's use to its elimination due to technological backwardness. It is related to the speed of technological progress rather than the operating time of the machinery.

Therefore, the service life of machinery is not necessarily the longer the better. Improper extension of the service life of machinery may sometimes cause economic losses and even hinder technological progress. Only by replacing machinery in a timely manner can technological progress be promoted, economic growth be accelerated, energy be saved and economic benefits be improved.