The harvester head is suitable for both thinning and final felling due to its versatility
The Kesla 26RH-III belongs in 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 good on even the most branchy trees. The head, weighing approximately one tonne, is suitable for mounting in medium-size harvesters and in 13 to 16 tonne excavators. Its sister model, the 24RH-III equipped with one rear knife and is a good choice for handling crooked broad-leaved trees and debarking eucalypts due to its shorter frame.
Customer deliveries of the first 3rd 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 a choice as a thinning machine’s all-round head, which can also handle final felling of smaller trees. 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 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 considered 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 extended structural service life of the Kesla harvester heads and improve their performance.
The hydraulics of the RH-III heads has 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 excellent efficiency of the 2WD feed system enables high performance even with base machines that have 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 a long time in various base machines around the world. The testing process has also involved forest companies and base machine manufacturers. Due 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. Deliveries of the KESLA RH-III series, covering the whole collection, will start in early 2022.