November 13, 2011
Focus on four areas for good dozer maintenance.
by John Gilbeck
Whether you’re moving rocks, pushing dirt, or shaping a haul road, you need your crawler dozer to provide maximum productivity and uptime while keeping daily operating costs as low as possible. You can achieve all three objectives through proper daily and periodic maintenance with attention to four specific components and systems.
1. Blade condition
Inspect the blade skin daily for obvious items such as cracks, holes, or dents. Next, focus on the cutting edge and end bits to determine if they need to be replaced. Check to see that each side of the blade or end bits is wearing evenly. If you happen to do a lot of side cutting with only one side of the blade, the wear will not only decrease the life of the blade, but also decrease the life of the undercarriage and linkage joints.
At a minimum, an excessively dull or worn cutting edge will cost you productivity and accuracy. Rotating, reversing, and replacing tips should be done regularly — if components wear beyond the limits capable of supporting hardware when reversed, you’ll need to install complete edges and bits, adding considerable expense. Always keep cutting edges, end bits, and related hardware on hand.
Before you finish walking around the blade, check the condition of the hydraulic hoses (and wire harnesses, if you have a grade control system on the machine). Rocks, dirt, and other debris that spill over or bounce off the blade can sometimes damage hoses and harnesses. Finally, make sure that all of the grease zerks will take grease for each joint.
2. Blade pitch
Proper blade pitch for the application and material being moved is very important to dozer performance. If your dozer has adjustable blade pitch, this area should be inspected to ensure it is functional. This feature needs to be utilized to maximize dozer performance. In general, a mid-pitch position is appropriate for general applications, but pitching the top of the blade forward or backward from this position can significantly change dozer performance. Please refer to the manufacturer’s operator manual for recommendations and adjustment information regarding this important area.
3. Hydraulics and other fluids
The hydraulic oil level should be inspected each day before startup. Some sight gauges allow you to also see the condition of the oil, giving you the chance to tell if it has been overheated or appears burnt. If the system is equipped with a breather, inspect this area for signs it is plugged. Keep it clear to prevent contamination from entering the system. Also, inspect the wiper seals on all hydraulic cylinders daily. A damaged seal can allow contamination into the system. Finally, check the condition of hydraulic hoses.
Every fluid level, not just hydraulic oil, should be checked on a daily walkaround. If a level is low, inspect for leaks and initiate repairs. Service doors and panels provide very good access to view areas where leaks can develop, so make it a point to look behind them.
Oil analysis is a very valuable tool in managing overall maintenance costs. Take samples of each machine system every 500 hours. If a particular system shows indications of abnormalities, sampling can be accelerated as needed. Regular analyses will allow you to proactively manage component life, maximizing uptime and minimizing operating costs.
Don’t forget about the coolant. Inspect coolant levels each day during your walkaround. The sight gauges and overflow bottles are easy to access and read. If levels are in range, you only need to do a visual inspection for leaks. The coolant temperature gauge will also give you real-time information on coolant system performance during operation.
The undercarriage system is the most critical system on the dozer. It’s also the most expensive to maintain and repair over the life of the machine — that’s why daily inspections and periodic maintenance are vital to operation.
Undercarriage cleanliness and track sag are two items that should be checked every day. While it’s true that track frames are designed to shed material, areas around the sprocket, final drive housing, carrier roller, and front idler should be cleaned at the end of the work day, especially in muddy or freezing conditions. If material becomes packed around rolling parts and freezes overnight, those parts may not move properly and can lead to seal failures and shorter component life.
Track sag — track tension — should also be inspected daily. A track chain that is too tight can increase track wear by 50 to 70 percent as compared to a properly adjusted track. Track chain that is too loose increases the risk of derailment and track kinking. Use an ultrasonic measuring device to help speed an accurate inspection. In addition, a visual alignment check should be part of your daily tasks.
Also use the daily inspection to look for specific kinds of wear. Wear on the track link-pin boss is an indication of bottom roller wear. The position of the idler block in relation to the track frame can be an indication of increased seal failure leading to track pitch extension (internal pin and bushing wear).
Many operators choose to turn pins and bushings as a way to maximize the life of sealed and lubricated track chains. This is particularly common where the link wear is much slower than the bushing wear. If links are around 50- to 60-percent worn at the turn, the operator can usually perform a pin and bushing turn then “run to destruction” on the back side of the bushing, utilizing the entire link and bushing life.
Daily inspections aren’t the only way to minimize wear. Good daily operating techniques play a part. Some basics include limiting high-speed reverse operation because component wear is three times greater in reverse than forward, and limiting unnecessary turns and counter rotation. It’s also a good idea to choose the narrowest shoe possible for each application and ground condition. This will also help extend undercarriage life.
Most crawler dozers on the market today come with telematics systems. These systems combine wireless communication with global positioning technology to give the operator location, hours, and diagnostic information. Using these items will help keep you up and running and catch potential trouble before it occurs. You can have more control over machine maintenance than ever before thanks to this technology.
Be sure to take advantage of the following:
• Machine location and hourly usage information that will allow you to schedule routine maintenance as needed without having to rely on daily reports from the field;
• Component pressures and temperatures;
• Fuel consumption readings;
• Machine utilization modes; and
• Machine system alerts — if your machine is equipped with this capability, you can set it up to be notified if a critical system on the unit is not performing properly.
Other in-cab indicators on dozers illuminate when there are specific problems, providing diagnostic codes that can alert operators and technicians. Blending what you see through daily visual inspections and maintenance on the job site with machine monitoring will enable you to keep your dozer running longer — at peak efficiency.
Jon Gilbeck is product marketing manager, crawlers, for John Deere Construction & Forestry.