Logmech solves Mkhoba Forestry’s steep slopes quandary
Harvesting and transport specialist Mkhoba Forestry has invested in the proven TimberPro 725D levelling harvester and SP Maskiner 761LF head combination to address steep-slope cut-to-length operations in south-western KwaZulu-Natal.
Mkhoba Forestry is based in Harding and is contracted by Merensky Timber’s Weza Sawmill in the Ugu District to harvest, extract and transport pine to the mill and to the port in Durban. Siyabonga Cosmos Shoba, managing director of Mkhoba, says they ordered the new TimberPro harvester from Logmech last year for delivery this year. Logmech lent them an older machine for trial and operator training until the new machines arrived.
Shoba says it is a business imperative for the company to have a reliable harvester fitted with a robust head that measures and cuts accurately.
“Our contract with Merensky is for 14,000 m3 of pine saw logs per month, usually cut to lengths of 6m, 5.4m, 4.8m, 4.2m, 3.6m,2.6m, 2.4m and 2.2m. Just over half of the cut, 6,000 m3, consists of 5.9m and 4.8m lengths for export markets. We must meet the customer’s specifications because our reputation depends on it”, Shoba explains.
“We specialise in steep slope harvesting, and our two Hitachi excavators are not ideal for working slopes. We tried different combinations of carrier and harvesting heads before settling on the TimberPro 725D purpose-built tracked and levelling machine”, he says.
“We also found that eucalyptus harvesting heads are not ideal for pine stems because they cannot consistently supply the accurate lengths we demand. Our trials showed that the calibrated SP 761LF is the most accurate head for pine and best for the diameters we work with”.
The SP 761LF head
Ryan Chase, Logmech’s technical manager, says the SP 761LF is the largest head in the SP Maskiner range and purpose-built for pine, although it can be converted to harvest eucs. Chase says the SP 761LF delivers peak performance on stands with a diameter of 20 to 56cm; however, thanks to the LF system, it can cut larger diameters efficiently.
“The LF stands for low friction. It is all about proportional pressure. The head features LogHold, a patented system that controls the delimbing knife pressure against the trunk and ensures that it is held in the right position”, Chase explains.
When the feed rollers close on the trunk, they provide maximum carrying force and are at their greatest angle. As the feed rollers carry the trunk, the pressure on the delimbing knives is reduced, and they are angled slightly inwards, forming a V-shape.
The delimbing knives have long cutting edges that cut the branches as they are fed through, rather than breaking them off. The LogHold and proportionally controlled delimbing knives system process stems easily and quickly with less friction than traditional feed rollers.
Cutting assortments
Shoba’s teams are prepared for all eventualities. Weza’s assortments vary widely because they include saw logs for Weza, other sawmills in the area, and export-grade round wood. Sometimes it includes 2.4m and 2.5m logs for pulp customers.
The specifications are entered into the harvester’s onboard computer, which ensures that each log is cut according to value lists or preferred length/diameter definitions, thereby reducing waste and increasing profit per log. Shoba is using the Dasa Forester and the StanForD standard bucking system. Chase says that although the touch-screen system is not Windows-based, it provides all the data needed to analyse their productivity.
The machine can handle up to nine assortments, which allows Shoba to run an entire harvesting operation. Although it can work automatically, Shoba has opted for a quality-based operator-assisted approach. When the head picks up and starts delimbing a tree, it sends the dimensions to the operator, who selects the required cutting pattern and stacking process.
The operator
“The machine tells the operator what it is cutting, and he makes the decisions”, Shoba says. “We are not running fully automatically because the system is too fast, and the extraction teams would fall behind”.
Shoba is impressed with his harvesting teams. “Harvesting looks easy when you see it happening, but it isn’t. We trained two operators from scratch on the TimberPro, and it took them about two months to learn the machine and the head. It is not easy to find people with the dexterity and spatial awareness who can adapt to safely operating a harvester”.
The TimberPro 725D
Chase says tracked levellers are at home on steep slopes, and clients specify whether they want a full-spec automatically levelling machine that uses sensors to determine the cab's angle, or not.
Shoba has opted for the manual version, which means the operator must watch the inclinometers in the cab while climbing and navigating rocks and obstacles and adjust the cab to keep it stable and level. The cab position can be corrected by 24° forward, 7° rear, and 24° to each side, ensuring the operator can work in extreme conditions with a perfectly level cab.
Significantly, the 725D, like all TimberPros, is ROPS (roll-over protective structure) and FOPS (falling object protective structure) certified. Chase says these are critical safety systems that keep the operator safe should the machine roll over.
In addition, the cab has three emergency exits, air conditioning, a heated seat and 30mm-thick polycarbonate windscreen and windows to protect the operator in the unlikely event of a hot saw tooth breaking and striking the windscreen.
Advantages of TimberPro
Chase says TimberPro harvesters have a reputation for working on steeper slopes than other machines, and he is proud that Logmech now supports 21 active machines in South Africa.
The D Series has the new 9-litre Cummins Tier 3 engine that works with South Africa’s diesel rather than the expensive Tier 4 or 5 engines specified for refined fuel in EU and US markets.
The TimberPro line of machines comes standard with 360˚ continuous rotation, allowing the operator always to face the line or work. This feature also gives the operator the ability to remove and stack timber from 360˚ around the machine, including the option to work over the front of the machine, sides and rear.
When it comes to maintenance, Shoba says there isn’t much to do at the end of each day. The TimberPro is auto-greasing, so they grease the fuel nipples on the head, clean the inside of the cab and check the hydraulics and cutter bar oil.
Chase says that the fins and bushes are over-engineered to ensure less wear and tear. “Another reason our customers enjoy low maintenance costs is that we have had an input into the design. We watch operations and listen to the operators to see where improvements can be made.
“When our customers encounter issues, we inform TimberPro or SP and suggest design changes. The OEMs upgrade and send us the parts. No changes are made for the sake of changes, purely based on feedback”, he explains.
“One of the biggest advantages for fleet owners is that the top ends of the TimberPro 725, 735 and 745 all share the same specifications. Only the bottom is different when it comes to the wheels and tracks. All parts are standard, which improves the machine's serviceability and don’t need a storeroom of parts”.
