Straightpoint Load Cell in tree felling application

The wireless 25,000lb capacity Radiolink plus was utilised by arborist Adaptable Aerial Solutions LLC beneath the hook of its Palfinger knuckleboom crane. Its main functions were to avoid exceeding the safe working load limit of the ropes and rigging hardware, and to avoid compromising the structure of the tree in relation to dynamic forces and critical angles.

Four arborists from Adaptable (or Craneva, as it is also known) worked at heights of up to 90ft to bring down the trees piece-by-piece: first branches were removed, then the trunks. The team employed spliced eye balancing slings and endless loop slings. The balancers were tied with a non-binding hitch and the roundslings were set in a choker configuration using shackles and hooks for attachment at the choking point to prevent fabric on fabric friction.

Wood weights were calculated in advance using a green weight log chart that provides a general guideline by species and size. On-site, the load cell recorded the smallest pick at 1,625lb and the largest at 6,500lb.

Steve Connally, of Adaptable Aerial Solutions, said: “The crane doesn’t have a load moment indicator as a cable crane would have. The controller shows the percentage of load on a LED light cluster. Since the wood weight varies considerably with environmental factors, time of year, and the number of branch unions, it’s necessary to know the weights of the picks in relation to the load chart and strength of rigging components. Each lift weight is evaluated in relation to the previous lift and the lift that follows. It’s a continuous harmony between the crane operator and the climber. This ensures we stay working within safe parameters.”

He added: “I am very impressed with the load cell. For my application it is perfect in weight, design, and ease of use. The data from the load cell allows me to pre-tension picks as the climber is cutting. As with any lift, weights, angles, and distances are essential information. Services I sub-contract for have been equally impressed with the Radiolink plus.”

The 50tm, remote-controlled, Palfinger articulating crane offers anywhere from 1,440lbs to 22,700lb of capacity, depending where it is on its load chart. Connally is a NCCCO-certified crane operator and has been using cranes in arboreal applications for 20 years. He and the team are fully trained in arborist rigging and technical rescue rigging operations. Connally is also an instructor at the Crane Safety Climber School, a class for arborists working with cranes for tree work.

He explained that tree felling is more complicated than many realize; it simply isn’t a case of heading to the foot of one with a chainsaw or an axe. “Trunks are taken, when possible, at lengths to fit specifications of the saw mills or pulp producers” he said. “Procedures typically depend on the potential hazards on the ground, ease of processing, quickest method, and the available workspace—not to mention customers who want to maintain a perfect lawn. These trees were all on the property line; we had to ensure that power lines, pools, fences, structures, and understory was unharmed.”