Traction aids can improve machine performance in adverse terrain. The trick is to understand all variables and choose a configuration that provides the performance benefits without sacrificing tire lifespan, or risking damage to the machine drivetrain system.
There are many types of forestry tires and many traction aid styles and brands. The traction aid must be properly matched to the tire. It must be installed correctly and maintained. And the tire itself must be properly maintained. Let’s break this all down.
Factory approval is required
First off, to keep machine and tire warranty coverages intact, all traction aids must be Tigercat factory approved before installation. There are many configurations that most certainly will damage the drivetrain or tires. Work with your Tigercat dealer to ensure the proper documentation is submitted and approvals are received.
Following is a brief overview of the three main types of traction aid hardware and some important considerations surrounding each. In addition, it is important to remember that dual tire installations are considered traction aids and must also be approved.
To keep machine and tire warranties coverages intact, all traction aids must be Tigercat factory approved before installation.
Wheel chains are installed over individual tires and are commonly used to provide additional traction in ice and snow. There are many chain and cleat patterns available, each is designed to provide optimal performance in specific conditions.
Wheel chains add significant weight to the machine and do not increase the footprint of the machine. In addition to increasing fuel consumption, the added weight results in higher ground pressure, and may cause increased ground disturbance.
It is important that the chains are correctly sized and installed to avoid tire damage. Chains should be regularly inspected and tightened according to manufacturer instructions.
Wheel tracks, like chains, are installed tightly over individual tires, providing significantly increased traction, while offering protection for the tire.
Wheel tracks meaningfully alter the rolling circumference of the wheel. The increased circumference, along with the additional weight of a wheel track, reduces maximum tractive effort and increases fuel consumption.
Wheel tracks must install tightly on the tire. Deflating the tire slightly before installing the track can help tighten the track to the outside surface of the tire when the air pressure is then increased to the correct operating pressure. It is very important to maintain the tire manufacturer’s maximum recommended operating pressure. This provides additional support for both the track bars and sidewalls of the tires.
Differential locks should be used sparingly when running wheel tracks. Operating differential locks in good traction conditions will cause the differential locks to slip while travelling through a turn. This will increase wear on the differential lock clutches.
Band tracks are designed to install on bogie-style axles. They add significant weight to the machine, increasing fuel consumption, but also increase the footprint. This can potentially reduce both ground pressure and soil disturbance.
Band tracks are designed to fit specific tire sizes and brands. Care must be taken to ensure compatibility. For example, imperial sized tires designed to run on four-wheel drive skidders have surface curvature across the width of the tire that makes running band tracks very difficult. They will consume significant engine power and walk off the tires relatively easily.
A properly sized track shoe for a given tire will have sufficient clearance between the sidewall and the track guides. There should be approximately 10 mm (⅜ in) gap on each side of the tire, between the sidewall of the tire and the track guide. Too little clearance will cause excessive wear on the sidewall of the tire.
Correctly tensioned tracks should have 40-70 mm (1½-2¾ in) of sag between the tires. If the track tension is too low, the track could walk off the tires. If track tension is too high, running over obstacles could cause damage to the bogie structure, planetary bearing, and gears.
A properly sized track shoe for a given tire will have sufficient clearance on each side of the tire, between the sidewall and the track guides, approximately 10 mm (⅜ in) gap on each side of the tire, between the sidewall of the tire and the track guide. Too little clearance will cause excessive wear on the sidewall of the tire.
Band track shoes, or tread bars, are available with very tall grousers to provide additional traction in deep snow. This design requires substantially more power to move the machine than less aggressive grousers. Using tall grousers in applications with good traction will result in reduced tractive effort available to move the machine.
Like wheel tracks, differential locks should be used sparingly when using band tracks. In favourable terrain conditions, the differential locks will slip while travelling through a turn. This will increase wear on the differential lock clutches.
A properly sized track shoe for a given tire will have sufficient clearance on each side of the tire, between the sidewall of the tire and the track guides. Too little clearance will cause excessive wear on the sidewall of the tire.
Correct inflation pressure is critical
Forestry machines operate in extreme conditions, so tires must be properly maintained to avoid premature wear, as well as catastrophic and costly failures.
The most important factor in tire maintenance is correct inflation pressure. Tigercat’s tire pressure monitoring system or TPMS is an effective tool in monitoring inflation pressure. TPMS displays a detailed warning message for the operator via the machine control system touchscreen interface.
Tigercat’s tire pressure monitoring system or TPMS is an effective tool in monitoring inflation pressure.
In addition, the TPMS system for Tigercat skidders, forwarders and harvesters now integrates with RemoteLog telematics. If TPMS detects that the pressure of any tire is out of range, a warning message is sent to the machine owner through the RemoteLog interface. RemoteLog maintains tire pressure warning history, logging all out-of-spec occurrences. For machines without TPMS, it is important to check tire pressures daily.
The torque capacity of the tire bead is a result of the tire pressure and fitment. The load capacity of the tire is directly proportional to the air pressure in the tire. Operating an underinflated tire reduces the torque capacity and load carrying capacity and may result in damage or slippage between the tire and rim. Tire slippage on the rim will tear the valve stem on the tube and permanently damage the tire bead. It may also damage the rim knurling. Under inflation can also cause excessive heat buildup. This could lead to sidewall, bead or lining damage when driving over obstacles.
Operating an underinflated tire reduces the torque capacity and load carrying capacity and may result in damage or slippage between the tire and rim.
Again, it is essential to maintain the correct inflation pressures. Failure to do so could void your tire warranty and lead to expensive repairs or replacement. Refer to the tire pressure chart in the Operator’s Manual. Required inflation pressures are also usually printed on the tire sidewall.
Tire slip on the rim. If the knurled surface on the rim is worn, there is a chance of the tire slipping.
Traction aid configurations
Here are some general traction aid guidelines. Again, due to the wide variety of tires and traction aids, as well as other important factors such as application, it is essential to work with your dealer to obtain factory approval for your specific configuration prior to the installation of any traction aids.
For four-wheel skidders and feller bunchers, the best configurations are identical chains on all four tires, or identical wheel tracks on all four tires. Assuming all tires have equal wear, this eliminates potential issues related to differences in rolling circumference and ensures equal gripping characteristics on all four tires.
For six-wheel skidders and harvesters, there are several possible configurations including:
Chains on the axle and band tracks on the bogie axle
No traction aid on the axle and band tracks on the bogie axle
Chains on axle and wheel tracks on the bogie axle
No traction aid on the axle and wheel tracks on the bogie axle
However, wheel tracks are never permitted on the axle when band tracks or wheel tracks are applied to the bogie axle. This will cause increased fuel consumption and excessive wear on the drivetrain components.
For eight-wheel harvesters and forwarders, the best configurations are identical wheel chains on all eight wheels, or four sets of identical band tracks.
For these configurations, contact your dealer for approval. You can also discuss other possible combinations which must be evaluated on a case-by-case basis. It is also important to note that dual tires installations are considered a traction aid. Factory approval is required to ensure a valid machine warranty. To prevent overloading the wheel bearings in dual tire configurations, the outer wheel must be smaller in diameter than that of the inner tire. Contact your Tigercat dealer for more details.
Adopt these best practices to maximize the life of your tires and protect critical drivetrain components:
Work with your dealer to get factory pre-approval before installing traction aids.
If your machine is not equipped with TPMS, check air pressure in all tires daily.
Regularly inspect tires for damage, especially if using traction aids.
Ensure that traction aids are properly tightened according to manufacturer instructions.
Clear soil, snow or debris from tracks, chains and tires.
Engage differential locks in anticipation of difficult terrain, before wheel spin occurs.
Whenever possible, select the best driving path to avoid obstacles.