Equipment Type

Use Preventive Maintenance to Stop Recurring Failures (p.2)

May 01, 2008

No time for failure

Chris Ryan, equipment vice president for Boh Bros. Construction, relies on engine oil analysis and emphasizes the importance of keeping fluids clean to ward off equipment failures.

"Failure analysis is after the fact," he says. "What we do is have regular inspections, daily reports from the operators, oil analysis, and service reports. It's the combination of these, not any one of them, that we rely on. We use each one to validate the others so we don't incur a failure. The operative word is failure. If a failure occurs, it's a failure within the system, not simply a failure of a component."

According to Ryan, the cleanliness of fluids can never be taken for granted.

"We try our best to keep all fluids clean: fuel, hydraulic oil and engine oil," he says. "We have service trucks with reels on them, and we have reels in our shop to make certain the product is delivered in good condition. One manufacturer of paving equipment requires you to put hydraulic oil into a separate tank, and hand-pump it through a filter and into the reservoir. I think that speaks to the fact that even clean oil isn't necessarily clean enough."

For the 1,600 to 1,700 units in the Boh Bros. fleet, Ryan tracks and analyzes trends and performs stereograph analysis on engines and hydraulic systems.

"We also do particulate counts on hydraulic systems," he says. "Pressures and flows are done periodically. As you get wear on hydraulic pumps, they start to trend downward, and you can see it coming. You can schedule something like that for a component replacement."

Ryan says he's knows a lot of good people who swear by component replacement based on time in service, but he has found the operational variables are so great that he can't justify doing that for all equipment across the board.

The data Boh Bros. collects is organized in three categories. Category one is for safety issues that must be handled immediately: The machine is shut down. Category two is for a failure that could lead to other failures: The machine continues to operate, but is monitored. Category three is cosmetic.

"Cracked glass, a dented panel, or anything that's not going to interfere with the function or safety of a machine is cosmetic," says Ryan. "We put the machine in line for attention, but often we wait until the next time it comes in to the shop to do the repairs."

Machine type, application and other variables are used to determine maintenance schedules.

"Lifting and over-the-road equipment maintenance is compelled by law," he says. "Certain things, such as brake adjustments, tire treads on trucks, and oil leaks, have to be taken care of or the unit will be put out of service. On average, our rolling stock is brought through the shop every 60 days for service inspections and corrective action. Our cranes are inspected daily by the operator; an inspection by the equipment department is made at least every 60 days for functional and safety issues, such as hoist cables, load lines and booms."

For basic dirt equipment, Ryan relies on daily service and inspection by the operator, and periodic service by the company's service trucks.

First line of defense

Ron Hutchinson, CEM, at Barrett Paving Materials, is responsible for a fleet of 200 units. Oil analysis is the bedrock of his PM program and the first line of defense against equipment downtime.

"Every time we change the oil in a machine, we take a sample," says Hutchinson. "A lot of times, we sample oil even if the equipment is not due for service. We'll get a reading and then sample again at the 250-hour service check to monitor oil life."

If any repeat failures show up, Hutchinson takes a closer look to try to determine if the failure is due to operator errors, application-related issues or equipment problems, or whether a better machine might be needed to prevent that particular type of failure.

But, says Hutchinson, oil analysis is just the start.

"The more data you have, the better data you have," he says. "With a paver, for instance, you need two or three years of data to know how many tons of mix went through the machine and what type of mix was used. Then you can see what wear factor is caused by what type and tons of material placed."

Hutchinson says record keeping, regardless of how it's done, is essential.

"You have to keep your records all in one place and not have them scattered around in different files," he says. "I keep all the data on my computer so I can monitor it."

Also, he says, you need a mechanism to spot minor repairs. Daily check lists should have a place for "required repairs."

"The key is communication," he says. "You have to make sure the shop is notified by someone in the field when a machine needs service. That will take care of small repairs while they are small instead of letting them go until a catastrophic failure happens."

Oil analysis and fuel management

Dale Warner, CEM, with CJ Miller, manages about a thousand pieces of equipment. Warner also uses PM histories to stop recurring failures.

Warner uses PM histories focused on two factors—oil analysis and fuel management.

"The one thing we don't do is think if one machine ran for 3,000 hours, another one will do the same before it blows up," he says. "You can't measure workload in hours. If everything were equal, maybe, but when a piece of equipment moves from one job to another, conditions and applications change. One time you can be working in rock; another time you're working in mud: In those two applications, the gallons of fuel used and the work load vary. Because of that, hours can't really predict failure. Everything depends on the history of a particular unit and its individual work load."

Warner bases PM scheduling on fuel consumption, and says, while the PM for trucks is a little different than dozers, the schedules are the same.

"One type of unit runs longer than the other," he says. "For example, we have articulated trucks running up to 700 hours on an oil change. Other trucks do 300 or 400 hours because of where they're hauling."

The fleet's oil analysis data is captured and stored by the laboratory that analyzes the oil samples.

"The data is accessible to us online whenever we need it," he says. "We can also get a hard copy from the lab if we want it."

Fuel management is handled internally, and Warner says the company is in the process of installing an automatic fuel-tracking system with about 80 percent of the fleet already converted.

"The system records when fuel was stored in the fuel truck and when it was put into a machine," he says.

When the fuel trucks return to the yard, a wireless system sends the information to the computer, which reports gallons of fuel used, hours operated, time, date, and job number.

"The Opak USA fuel tracking system we use has totally automated data retrieval," says Warner. "The equipment has a sender on it, and the fuel nozzle has the receiver. When the nozzle goes into the tank, all the data is recorded. We also use the system to measure equipment utilization."

To get the biggest bang from using PM histories to stop recurring failures have a system in place that allows the procedure to work.

"It all starts with people," says Warner. "You have to have people who really care about what they're doing and people who pay attention to what they're doing. You also have to use quality products and have the support from top management to get the job done."

All four fleet managers agree that while philosophies, techniques and technologies may differ when it comes to using PM histories to stop machine failures, success requires the absolute commitment of top management.

Overall Sample Ratings
Company Normal Abnormal Severe Total
All Sites 1284 (58%) 894 (40%) 51 (2%) 2229(100%)

Severe Samples Problem Category Breakdown
Problem Count Percent
Water 17 33%
Wear 14 27%
Dirt 11 22%
Soot 7 14%
Visual Metal 2 4%

Problem Count Percent
Visual Metal 179 20%
ISO 166 19%
Wear 132 15%
Dirt 122 14%
Visual Debris 107 12%
Viscosity 84 9%
Water 47 5%
Sediment 42 5%
Soot 7 1%
Containment 7 1%
Fuel 1 0%

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