Tigercat has carried out a number of improvements on their 855C, 860C and 870C tracked carriers. The affected products include the H855C/LH855C harvesters, LS855C shovel logger and the 860C/870C feller bunchers.
The improvements are quite technical in nature, but it is important that we as technology users do not shy away from ensuring that we understand in detail how the equipment operates. The result will be that we can more accurately analyse and compare machines when making equipment selection decisions.
The changes are numerous, but the most noticeable improvement is the twin swing drive system which increases swing torque by 44%. At the same time, pinion loads are reduced which will result in extended swing system life. New swing drive gearboxes with larger bearings, a stronger gear train and a new swing system valve will improve machine performance and reliability.
Improvements to the hydraulic system include changes to the saw circuit, larger capacity pumps and improved valving and control systems. Tigercat indicates that one of the advantages that these hydraulic improvements provide is better feller buncher wrist control performance (see picture to the right).
What grabbed our attention is the addition of an operator controlled Energy Recovery (ER) on/off switch. When felling large timber up hill, the ER switch can be disabled, and in doing so additional stick boom-out force is obtained. The ER system “allows the operator to extend and retract the boom on a horizontal plane using a single joystick. In doing so, ER transfers energy back and forth between the main and the stick boom functions, reducing the total energy required and freeing this energy up for other machine functions or fuel savings”. The stick boom or "reach" joystick controls both the main and stick booms simultaneously, resulting in the attachment moving either away from or toward the operator. This allows the machine operator to extend and retract the feller buncher boom on a horizontal plane smoothly and quickly using a single joystick. The main boom and tilt functions operate in the traditional manner to adjust the height and angle of the attachment. Conventional boom systems are more inefficient at felling because they must mix two arcing motion functions to get the desired reaching motion. Important advantages of the ER boom system include improved fuel efficiency, increased production and reduced operator fatigue. Also, training for new operators is easier.
There has also been a focus on further parts commonality between all of the carriers listed above. Source: www.tigercat.com