FINNISH forestry equipment manufacturer Kesla has announced the launch of the new RH-III range, including the 24RH-III and 26RH-III.

The Kesla 26RH-III harvester head is suitable for both thinning and final felling due to its versatility and belongs to the highest volume size class of the market.

Equipped with four moving delimbing knives, the 26RH-III can handle even large trees with ease, and the delimbing quality is excellent on even the most branchy trees.

The head, weighing approximately one tonne, is suitable for mounting in medium-size harvesters and in 13–16-tonne excavators. Its sister model, the 24RH-III, equipped with one rear knife, is an excellent choice for handling crooked broad-leaved trees and debarking eucalyptus due to its shorter frame.

Customer deliveries of the first third-generation models, the 19RH-III and 21RH-III thinning heads, began at the beginning of 2021. The Kesla 19RH-III is a three-knife, lighter and more compact head specially developed for curved broad-leaved trees and debarking, making it also ideal for thinning in Scandinavian forests.

Equipped with two rear knives, the 21RH-III can handle even bigger trees and is an excellent choice as a thinning machine’s all-round head, which can also handle final felling of smaller trees. The heads are in a power-to-weight ratio class of their own, and the only ones in their size class made to last in continuous debarking of eucalyptus and acacia. Both models can be equipped with the Kesla mthGRIP accumulating grapple and multi-stem processing feed rollers. The Kesla 21RH-III is also available with Kesla’s unique proAX cutting knife, which improves efficiency in harvesting small-diameter trees.

Kesla’s largest heads, the 27/28RH-III and 29/30RH-III, have also undergone thorough renewal and now represent the design and technology of the third generation.

The design of the new models has progressed hand-in-hand with the renewal of Kesla’s manufacturing technology, and evolving automation has been taken into account in the design from the very beginning. The frame modules are machined as a one piece after the welding assembly, and the moving parts make use of casting to a great extent. This brings the structures’ dimensional accuracy to a new level. This, combined with heavy-duty axles and bearings, will further increase the already extended structural service life of the Kesla harvester heads and improve their performance.

READ MORE: 2021 harvesting heads round-up

The hydraulics of the RH-III heads have been redesigned. The starting point was minimized power losses, high net power and suitability for various base machines. The spacious hydraulic system of the heads can handle even a high oil flow with small losses, and the efficiency of the 2WD feed system enables high performance even with base machines with a modest hydraulic output.

Since the targets in terms of structural strength and power-to-weight ratio were set particularly high, the zero series of all the size classes have been tested for an exceptionally long time in various base machines around the world. The testing process has also involved forest companies and base machine manufacturers.

Thanks to their modular design, the new third-generation RH harvester heads can easily be optimised to operate in different circumstances, with different types of trees and with different base machines.

Mika Tahvanainen, director of logging equipment business at Kesla Oyj, said: "Our strategy as the leading independent harvester head manufacturer guides us to develop our products so that they can be flexibly adapted to different conditions and base machines. It makes us a superior partner for manufacturers of excavator harvesters and those harvester manufacturers whose product line does not include harvester heads."

Deliveries of the Kesla RH-III series, covering the whole collection, will start in early 2022.