Company Announcement - Global leader STIHL has a history dating back to 1929. The company was founded by engineer Andreas Stihl, whose initial aim was to improve the timber industry by developing the first engine-driven two-man saw. This passion for innovation and premier practical applications continues to this day, with STIHL now a third-generation family-run business with a solid reputation for quality tools and equipment, based on the company’s investment in significant research and development facilities.

STIHL’s speciality Rapid Micro Harvester Special saw chain is evidence of the company’s legendary eye for detail and aim for perfection. Designed for professional applications under the toughest of working conditions, the RMHS saw chain has been developed to withstand the continuous high loads which are a standard element of highly mechanised timber harvesting operations. In comparison to standard saw chains, harvester saw chains are subject to extreme conditions such as a driving power greater than 30 kW, high chain speed and being pinched in the cut. High loads result in cracks radiating from the rivet holes that finally cause the chain to break.

The stressful conditions of continuous high loads experienced during professional harvesting operations exposes the individual parts of the harvester chain to constantly alternating tensile forces that can cause cracking and breaking of the chain. Now, with the RMHS saw chain, all parts of the chain have been specially strengthened to vastly reduce the risk of cracking while maintaining the usual high cutting capacity of all STIHL harvester chains. This increased durability adds value through longer service life and less chance of downtime.

How does it work?
Cutting results from a professionally used harvester depend largely on the design and power of the drive unit, the condition of the guide bar, and the working technique. The guide bar and saw chain have to do the heavy work of actually cutting and so have the greatest impact on the machine performance and final results. STIHL manufactures saw chains especially for the demands of professional wood harvesting operations. Extensive R&D has proven the ideal material mix for every component, and with meticulous maintenance, the RMHS speciality saw chain will ensure less friction for smoother operation and a resultant increased wear period. The RMHS is a semi-chisel chain with slim, straight-sided cutter. The offset depth gauge of 1.0mm makes this a very smooth running chain, so that the chance of chain breakage is minimised. The sliding surface has been increased through the patented asymmetric shape of the toe and heel, resulting in considerably reduced pressure on the cutters and hence the longer service period. The saw chain is marked with the letters HS on the cutters and an arrow point on the tie straps to show the direction of rotation.

Reduced stress throughout
All heavily stressed elements of the STIHL RMHS have been specially strengthened for their demanding role, so that the forces acting on the drive links, tie straps, cutters and rivets are more effectively and evenly distributed over the entire chain. The reinforced tie straps, drive links and rivets are designed for the high driving power of harvesters and the resultant high loads imposed on the chain. The reduced distance between the tie straps increases flexural strength and reduces the risk of chain breakage. The Rapid Micro Harvester Special saw chain therefore has up to a 70% longer service life than conventional harvester chains with a 2.0mm drive link gauge.

Making the RMHS work at its best
The RMHS saw chain has wide running faces to reduce the load on the chain, guide bar and sprocket. To maximise the benefits of the chain's wide running faces and extend the service life, it is necessary to check that the widths of the running faces on the chain, guide bar rails and chain sprocket match. Narrower saw chains cause a narrower wear pattern on the guide bar and chain sprocket. If a new RMHS chain is mounted on a bar worn in such a way, the edge pressure will be increased. This results in excessive wear or damage on the new chain. It is recommended that a new chain sprocket and a new guide bar be installed with the new chain to ensure optimum break-in and operation.

The STIHL RMHS is designed for use on hydraulic harvester heads only, and is a standard-profile, semi-chisel chain made to withstand the tough requirements of professional mechanised timber harvesting. Designed by international experts STIHL to last longer than competing chains and to minimise expensive harvester downtime, the RMHS is an essential investment for any professional timber harvesting operation.