Wringing the Rag Out
Understanding the various levels of machinery components – and their corresponding replacement schedules – will help operators leverage equipment life.
by Gerald Green
Whether an aggregates producer owns one machine or a large fleet, leveraging its equipment management plan to wring the most out of its asset for the lowest owning and operating cost can be tricky. Often times, operators believe the way to get the most from their machinery is to push the major equipment components (including engines, torque converters, transmissions, differentials, and final drives) to the point just before they fail. In reality, this may not be the best way to get the most out of equipment.
Most major components have three levels of parts in them. These levels include the following:
Level One: Parts and pieces that are designed to carry the brunt of the load and wear. Examples of these in an engine include bearings, rings, seals, and gaskets. These parts have a design life of one overhaul. They are designed to protect the major components that are attached or combined with such parts as connecting rods, crankshafts, and pistons.
Level Two: These parts and pieces are designed so that – with proper care, planning, and maintenance – they should last through two rebuild cycles. In an engine, examples of these include pistons, liners, camshafts, and lifters. Manufacturers may offer educational materials and specifications designed to assist operators and dealers in making “reusability” decisions on their parts.
Level Three: These pieces and parts should last several rebuild cycles. Examples of these in an engine include crankshafts, blocks, or major castings such as heads and covers.
Most equipment management experts agree that with the right planning, 80 percent of earthmoving equipment repairs should be scheduled in advance of failure. Yet, they estimate that 80 percent of repairs actually occur after catastrophic failure. Experts also note that, even without figuring in lost production, failure repair costs typically run triple the costs of repairs made prior to failure.
With a better understanding of the types of pieces and parts inside a major component, an operator can begin to formulate improved equipment management strategies. As an equipment-condition monitoring strategy is developed, an operator may be tempted to run equipment past its projected point of overhaul. After all, “If it isn’t broke, don’t fix it!”
In reality, this may press into the life cycle of those critical, potentially reusable Level Two parts. When the component is finally rebuilt, the operator may find that the risk factor of a progressively worn Level Two part no longer makes it a candidate for reuse; causing more parts to change at overhaul. This exponentially escalates cost even though the component did not stop performing or fail. In other cases, an operator may feel that downing the equipment to overhaul uses up too much potential production so an exchange or remanufactured component is used. In the process of rebuilding these exchange components, the dealer or manufacturer rebuild entity may be forced to install all new Level Two parts because of the lack of component history and to mitigate the risk of failure.