Winter shut-down precautions for large mining equipment
January 2, 2014 | Best Practices
This article is excerpted from VISTA's Silver Series training program, Heavy Equipment - Intro & Safety
Large mining machinery, like a world-class athlete, needs time to cool down at the end of a long run, even if the ambient temperature is downright frigid.
An Olympic sprinter, for example, walks around, taking deep breaths and allowing his or her body to slowly return to normal heart rate and respiration. Of course, there's no need to "walk" your machine around after a hard day's work, but there are a few things that you must do before you call it a day. Your machine needs to go through a cool-down period.
Where and how to park the machine
When the work is done and the machine is going to be parked for a period of time, find a suitable place that is dry, flat and out of the way of other traffic and working machines. Lower all raised components and attachments, place the transmission or motion selector in the neutral position and apply the parking brake. If the machine has a lockout control for the hydraulic system, be sure it is disabled as well. Now slowly begin lowering the engine RPM to a point where the engine is running at about one-third of its full speed.
Bring down the machine to rest condition
Your goal is to bring the machine down to a rest condition without causing harm to any components. The most critical component on most large machines is its turbocharger. When an engine has been working at full RPM, the turbocharger is extremely hot and can be spinning at speeds in excess of 100,000 RPM.
A turbocharger is precision built, constructed of special materials, and uses high-quality, high-speed bearings. In order for a it to survive hundreds of hours of hard work, its key components must receive a continuous supply of engine oil. The oil does two things: It lubricates the bearings and it carries away some of the heat from the immediate area.
Preserving the oil supply to the turbocharger
Preserving the oil supply to the turbocharger is the first and most important reason for having an engine cool down procedure. The oil circulating through the turbocharger cannot be stopped or interrupted. If it is, the turbocharger will suffer damage and this very expensive component may need to be replaced. Unless there is an emergency, never shut off a hot diesel engine when it is running at full RPM. The turbocharger must also have time to wind down from its high rotation speed and it needs time to lose much of the extreme heat that builds up when the engine is working hard.
Bring the engine temperature down
It is also important to bring the rest of the engine down to a lower temperature before it is shut off. When the engine is running under load, the cooling system is continuously carrying away heat and maintaining an optimum engine temperature. If a hot engine is shut off, the cooling system is no longer able to do its job. For a short time, the temperature in certain parts of the engine may spike dramatically. This increases the potential for engine damage.
We stated that engine RPM should be brought down to about one-third throttle. At this speed, the cooling system is able to work at full efficiency and can dissipate the greatest amount of heat in the shortest amount of time.
When to shut down the engine
Every engine is unique: Each engine develops and dissipates heat at a different rate. For best results, you should monitor the coolant temperature gauge of your machine and watch for the expected drop in temperature. Then, after the engine has gone through a cool down period of at least five minutes, lower the engine to idle speed, wait 10 to 15 seconds and shut the engine off.
Finally, before leaving the machine, move key switch and master disconnects to the off position.
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