Loading timber isn't always a walk in the park: A work shift in the cab of a forestry crane can be numbing, just as any sit-down job, and foul, rainy weather makes conditions worse. Ergonomics can help.
Loglift Jonsered's Salo factory in western Finland has experience with forestry cranes that dates back to 1965. Ergonomics have been developed for just as long.
"We have our own research and development department, but ergonomics are developed by everyone - including customers with their wishes and requirements", says Loglift Jonsered's Kalevi Sjöholm, OEM, Business Development Director for Loglift Jonsered.
About 80 per cent of the truck-mounted LOGLIFT and JONSERED forestry cranes are equipped with an operator's seat located behind the boom or next to it in the open air. However, an increasing number of forestry cranes are being equipped with a cab.
"The cab is a Scandinavian phenomenon, but it is becoming increasingly popular also in the United States and Central Europe - generally in areas where you need shelter from the cold and rain", Sjöholm says and launches into a review of the ergonomics of LOGLIFT and JONSERED forestry cranes.
"If we start from the ground up, the first thing is the ladder; it is designed to facilitate the operator's ascent from the ground to the operator's seat. The ladder has wider steps, a short rise and a rough surface that doesn't accumulate ice or snow", Kalevi Sjöholm explains.
In the cab-equipped cranes, the control levers can be moved aside to make it easier to get in and out of the operator's seat. And with two doors, one on the front and one on the side, the operator can choose which one is most convenient for the situation.
About 80 per cent of accidents involving forestry cranes happen when an operator slips as he climbs up to or descends from the operator's seat. The crane's roughed steps and sturdy grip bars reduce the risk of falling. They help the operator pull himself up and also improve safety when timber is being loaded: If a log in the grapple were to swing toward the seat, the operator's legs are protected by the bars.
The next most common accidents occur during the servicing of forestry cranes. Servicing has been made safer by roughening also the surface of the servicing platforms and by increasing the surface area of them.
"Moreover, the valves have been positioned so that they can be accessed directly from the ground or conveniently from the servicing platform", Sjöholm explains.
The seat of the forestry crane is its own chapter in ergonomics; in both the open and the cab-equipped versions, the seat has been designed to support the lumbar back. The seat is also heated, which is especially important when working in cold temperatures. It stays warm and doesn't get as wet.
"The seat can be easily adjusted forward and back and up and down. Loglift Jonsered has patented this mechanism. Also the positioning and angle of the pedals and levers can be adjusted, and because the lever motion and the actuating force of the valves have been optimised, several levers can be used at the same time manually with ease. The cabs of the cranes come equipped with our patented mechanical controls, and digital electronic controls are optional. They take even less force to control the crane, so it is really effortless, and the movement speeds can be adjusted to suit the operator's preferences", Sjöholm says.
"In every detail, we have taken into account the fact that operators come in different sizes and heights", he adds.
The operator's seat can be moved partially to the side so that it is not directly behind the boom; this expands the operator's field of vision in the desired direction. The booms in LOGLIFT and JONSERED cranes have been designed to be as narrow as possible, and the piping runs close along the side of the boom. Unlike the boom, the diameter of the pipes and hoses has been kept relatively large to minimise pressure losses. This not only prevents energy from being wasted, it also prevents the pipes from becoming too hot, reducing the risk of operators burning themselves if they accidentally touch them.
The optional xenon lights take visibility to a completely new level:
"With the xenons it is almost as if you are loading in the daylight, even though it is night", Sjöholm says and adds that also the standard equipment halogen lights have good illumination. They are placed above the operator's seat and on the boom so that the light beam illuminates the target to be picked up and the surrounding area. Additionally, the yellow colour of the grapple makes it more visible in the dark. The colour of cranes installed on forwarders is usually black, as in many other Hiab equipment, but with a matte finish so that the light doesn't reflect off it in the dark and strain the eyes.
Another attribute facilitating the operator's work is the fact that with LOGLIFT and JONSERED equipment the operator can control the crane's stabilisers from the operator's seat. On soft terrain, stabilisers easily sink into the ground. Well-functioning hydraulics also add to operational ease; soft and precise movements make the crane more comfortable to operate and the work less taxing on both the crane and the operator.
A timber crane with an open operator's seat can be equipped with an optional weather shelter, which comes up behind the operator's back and covers his head. It offers protection from rain and wind. Weather is not a problem with cab-equipped cranes.
"Cabs have a heater and fresh air fan as standard equipment, and air conditioning for hot summer weather is an available option", Kalevi Sjöholm says.
He compares the cab to a women's shoe: It looks small from the outside, but is roomy and comfortable on the inside.
"In the cranes that have a cab, the valves have been placed outside the cab so the smells, noise and heat don't carry into the cab. Additionally, noise-suppressing materials have been used in the walls and roof of the cab. When selecting the materials for the foot area the number-one criteria has been the ability to keep it clean", Sjöholm notes.
The list goes on: "Levers and push-buttons have been placed within easy reach of the seat. A hydraulic cylinder diagonally lifts and lowers the entire cabin; in the diagonally back position, the swaying motion caused by the slack is decreased and thus reduces the load experienced by the operator."
And, just as with shoes, attention has also been give to the design. For example, the windshield of the cabin is curved - and not just for the looks.
"The curved polycarbonate glass doesn't cause reflections, it adds space and visibility and it's shock-resistant", Sjöholm reports.