The fix, again, is the same: If it feels off, put the load down. There is a wrinkle, though. Pulling a load closer to the truck increases lifting capacity, but the debris body can only hold so much. Pack it too tightly, and the load may become difficult to unload later. Englehart compared the process to playing Tetris: Material has to be po- sitioned efficiently without creating a problem for the next step. That balance between lifting capacity and usable space is another example of why operating these machines in- volves more than simply following a set of numbers. The operator is constantly reading the machine, the load, and the environment together. Rule 3: “Don’t close the jaws all the way.” The grapple on this truck uses a clam- shell rather than the thin, bypass-style jaws found on many log trucks, so it grips material differently. The jaws should be positioned below the horizontal midpoint of the load, allowing them to cradle the material while leaving some closing travel. If bark slips or compresses as the load is lifted, the jaws can tighten farther without losing their grip.
For this type of grapple, position the jaw just below the horizontal midpoint of the load — this allows the material to be cradled while securing the jaw's grip.
differently when an outrigger is placed on an unstable surface or when the weight is distributed poorly.
GRAPPLE TRUCK/LOG LOADER: A DIFFERENT KIND OF HEAVY The grapple truck’s stability problem is different from that of a skid steer. It is not necessarily about being top-heavy and tippy. Instead, it is about sheer mass meeting a relatively small contact patch. Unloaded, the truck weighs more than 40,000 pounds — more than twice the weight of a typical bucket truck — and all that weight has to be supported somewhere. Once the grapple begins reaching, lifting and pulling materi- al from different positions around the truck, the forces acting on that weight change. Here are four rules the Seacoast Tree crews follow without exception. Rule 1: “Set it up right or you’ll leave a mark.” Outriggers on solid pads are a must. The grapple’s footprint is small relative to the truck’s total weight, and skip- ping the setup step can leave a divot in someone’s driveway even when noth- ing goes wrong mechanically. Proper setup is therefore about more than preventing a tip-over. The ground itself becomes part of the equation. A machine that is stable on solid, proper- ly supported ground can behave very
Rule 2: “Stability is still a feel thing.”
Just like the skid steer, there is no sin- gle gauge telling the operator when the machine is safe under every possible load. The operator has to understand how the chassis responds as the grap- ple reaches, lifts and pulls. You raise the chassis until it feels sol- id, and lateral loads — most pulls come from the side — are the main thing to watch.
At Seacoast Tree Care, crews are encouraged to use their instincts when operating equipment, something that official manuals just can't teach.
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