Caterpillar doesn't advocate operating its excavator with the tracks in a retracted position. "The machine should always be operated with the undercarriage in the expanded position, unless travelling through a narrow access area such as a gate or between buildings," says Mumford.
ROI comes quickly
Return on investment from variable-width systems comes quickly due to increased utilization and, in some cases, increased productivity vs. comparable fixed-frame excavators. "The ROI is only limited by the amount of additional jobs requiring a narrow carriage machine that the contractor can add to his job schedule," says Golevicz.
The added stability offered by some models can further impact ROI. "The premium for the variable-width undercarriage is less than 5%," says Mumford. "This premium is quickly overcome when you factor in the benefits of additional stability, which translate into increased digging and lifting performance."
As an example, Anderson notes, "The difference in price of the Volvo EC15 BXR rigid frame and the ECBXTV variable frame is small at about 5%, much like the industry. The EC15BXTV's price includes a two-speed drive system. Stability and access give the owner/operator the ability to take jobs in tight places and on terrain that may not be accessible with a rigid frame machine."
Downsides to variable-width systems are few. "Generally, they will weigh a bit more than their counterparts and there is always increased maintenance due to the components needed in the expandible frame," admits Anderson. "However, the benefit of having the system far outweighs the added maintenance. Any time there are more components, more maintenance may be needed. Typically, it only requires normal inspection at service intervals."
Golevicz adds, "You can't ignore the fact there are additional moving parts and hydraulic components. These should be regularly inspected and maintained. These are not difficult tasks and will not increase the total maintenance time compared to a fixed-width machine by an appreciable amount."