Mitsubishi MM55SR Parts Identification and Maintenance

[MikePhua]

The Mitsubishi MM55SR is a compact, versatile mini-excavator that has been a trusted piece of equipment in construction, landscaping, and excavation for years. Understanding its parts and identifying them correctly is crucial for ensuring that the machine runs smoothly and efficiently. This guide explores key aspects of the MM55SR’s parts, common issues, and how to maintain the machine for optimal performance.
Overview of the Mitsubishi MM55SR
Mitsubishi, a renowned Japanese manufacturer, has been producing machinery for various industries, including construction and agriculture, for decades. The MM55SR mini-excavator is designed for small to medium-scale projects where space constraints and maneuverability are key considerations. This machine offers impressive power and performance relative to its size, with a focus on efficiency and ease of operation.
The MM55SR is equipped with a diesel engine that delivers the necessary horsepower to handle a range of tasks, from digging and trenching to lifting. It’s particularly appreciated for its excellent hydraulic performance, reliability, and the versatility offered by its compact design.
Key Parts of the Mitsubishi MM55SR Mini-Excavator
Identifying and maintaining the right parts is critical for the longevity and performance of the MM55SR. Here’s a breakdown of key components and their functions:

1. Engine
   The heart of the MM55SR is its engine, typically a 4-cylinder Mitsubishi engine that delivers about 38-40 horsepower. This engine is designed for both power and fuel efficiency, making the machine suitable for long hours of operation in a variety of conditions. Ensuring that the engine’s filters and air intake systems are clean is vital for preventing overheating and ensuring smooth operation.
   
2. Hydraulic System
   The hydraulic system is one of the key strengths of the MM55SR. It uses a combination of hydraulic pumps, cylinders, and motors to power the excavator's movements. Over time, hydraulic hoses and filters can become clogged or damaged. Regular inspection and replacement of hydraulic fluid and filters will prevent performance issues like sluggish movement or loss of power.
   
3. Boom, Arm, and Bucket
   These components form the machine's working arm and are subjected to intense forces during operation. The boom provides the lifting height, while the arm offers the digging range and reach. The bucket, typically made of hardened steel, is used for scooping and dumping materials. Keeping these parts lubricated and free from debris is essential for maintaining performance and extending their lifespan.
   
4. Tracks and Undercarriage
   The undercarriage of the MM55SR is designed to withstand rough terrain, but regular maintenance is needed to avoid wear. The tracks are one of the most exposed components, subjected to constant friction and stress. Inspecting the tracks for wear and replacing them when necessary ensures the excavator remains mobile and efficient. The drive sprockets, rollers, and idlers should also be checked regularly for damage.
   
5. Electrical System
   The electrical system of the MM55SR, which includes the battery, alternator, and wiring, is crucial for ensuring proper function. If there’s an issue with starting the machine or intermittent electrical problems, it’s essential to check the battery's charge, the alternator’s output, and ensure no wires are corroded or loose.
   
6. Cooling System
   The cooling system, consisting of the radiator, cooling fan, and thermostat, plays a vital role in keeping the engine at the correct operating temperature. A clogged radiator or a malfunctioning cooling fan can lead to overheating, which in turn causes the engine to run inefficiently and potentially suffer damage. Regular cleaning of the radiator and checking the coolant levels are necessary for preventing overheating issues.
   

Common Maintenance Issues and Solutions
While the MM55SR is a well-built machine, like any piece of heavy equipment, it’s susceptible to wear and tear. Here are some common issues and tips for addressing them:

1. Hydraulic Pressure Loss
   Hydraulic pressure loss can result in poor digging or lifting performance. This can be caused by several factors, including leaks in the hydraulic system, worn seals, or low fluid levels. If the hydraulic system is underperforming, inspect all hoses and fittings for leaks, replace any worn components, and ensure the hydraulic fluid is at the proper level.
   
2. Engine Overheating
   The MM55SR’s engine can overheat if the cooling system is not functioning properly. Common causes of overheating include low coolant levels, a clogged radiator, or a malfunctioning cooling fan. Regular maintenance of the cooling system—such as cleaning the radiator and replacing coolant—helps prevent these issues.
   
3. Track Wear and Tear
   Track problems are common in mini-excavators due to the constant friction against rough surfaces. Tracks can become loose or stretched over time, resulting in poor stability and traction. Inspect the tracks regularly and adjust the tension as necessary. If the tracks show signs of severe wear, replacement might be necessary to maintain optimal machine performance.
   
4. Fuel System Issues
   Clogged fuel filters can lead to engine stalling or poor fuel efficiency. Ensure the fuel filter is replaced at regular intervals and the fuel system is free of contaminants. Diesel fuel in particular can absorb water, which leads to corrosion and clogging of the filters and injectors.
   
5. Electrical Failures
   Electrical issues can cause erratic behavior in the excavator, such as difficulty starting or problems with lighting. Check the battery, alternator, and wiring for corrosion, and replace any damaged components. Regularly cleaning the battery terminals and ensuring a secure connection can help prevent many electrical issues.
   

Parts Identification for Mitsubishi MM55SR
When parts need replacing, identifying the correct part numbers is essential. Some common parts and their typical identification methods include:

1. Engine Parts
   These include air filters, fuel filters, belts, and oil filters. Each of these components will have a part number stamped on the part itself, which can be cross-referenced in the owner’s manual or through a dealer.
   
2. Hydraulic Components
   Hydraulic pumps, motors, and cylinders often have identification plates that list their specific model and serial numbers. These should be checked before purchasing replacement parts to ensure compatibility.
   
3. Tracks and Undercarriage Parts
   Tracks, rollers, and sprockets often have part numbers stamped on the side. If these parts need to be replaced, ensure the measurements of the track width and length are correctly matched to the machine specifications.
   

Conclusion
The Mitsubishi MM55SR mini-excavator is a compact and reliable machine, ideal for a range of construction and landscaping tasks. Understanding the key components of the MM55SR and how to maintain them is essential for keeping the machine in peak operating condition. Regular inspections, proper part identification, and timely maintenance can greatly extend the lifespan of the machine and help operators avoid costly repairs. Whether you’re dealing with hydraulic system issues or track wear, a proactive approach to maintenance ensures that your Mitsubishi MM55SR performs at its best on every job site.