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Pins and Bushings

Pins and Bushings

Just like any mechanical component, when you use something it is going to get worn. Pins and Bushings are parts on equipment that are designed to wear. Especially in the tough conditions such as forest operations. Greasing at the proper intervals is going to ensure that you get the full life of your pins and bushings which can help to lower costs, reduce downtime and ensure top working condition of you machine. Something that should be understood is that when pins and bushings begin to get worn the component that it is driving, if it be a cylinder or other movable part, can begin to have movement. This movement creates negative energy which reduces the effectiveness of the driving part such as Delimbing Knives, Measuring Wheel, Felling link etc…

Replacing bushings as they show sign of wear will help to ensure top performance of your harvester head. Another aspect to consider is placing shims in between an installable component and the frame of the harvester head. This can also help to absorb negative energy and increase the pin and bushing life. Always refer to the owners manual for the correct parts and servicing tips of the above mentioned items.

Knives

Knives

Knife maintenance is one of the most overlooked areas on many operations.  Making this small task a part of the operators daily maintenance is the best way to ensure that the knives are well maintained.

Poorly maintained knives can reduce production significantly and add to the hourly operating cost through increased fuel consumption and decreased component life from overheating the hydraulic system and higher than normal structural stress.  Delimbing knives, as a result often fail or wear out prematurely on many harvesting machines. Also, poorly maintained knives can cause inaccurate log measurements which have a negative impact on the forwarder, log trucks and the end user, the mills, who manufacture the timber.   Only about 10% of harvester heads maintain knives to an acceptable level.

The most common issue with knives is the lack of daily care which leads to a condition that often happens within the first 1000 hours or so of a new knife which can affect performance for the entire life of the harvesting unit.  Knives that are not maintained daily gradually get damaged and worn from normal use to a point where it can be difficult to repair it to it’s original condition.

Hoses

Hoses

More than 70% of spare parts sold for hydraulic machinery are used to replace defective components. The cause of 90% of these defects can be traced to improper operation or maintenance.  We know from our experiences around forestry operations that this statement is probably quite accurate.  One of the most common points for contamination to infect a hydraulic system is through hose replacement.  Hydraulic hose consumption on forest harvesting equipment can be much higher than that of road building or mill yard machines.  This is due to the fact that forest equipment is subjected to a much harsher environment.  The higher than normal hose failure rate is a key indicator that your machines are also being subjected to higher than normal levels of contamination.  From one single hose failure there are several ways contamination can enter a hydraulic system.  First by replacing the hose the system is opened and subjected to the normal dirty conditions in the forest.  Secondly contamination can come from improper storage of hoses and thirdly by opening the system again to replenish the oil lost from the hose failure.  This tip is about reducing hose failures thus reducing the contamination in your hydraulic system.

Hydraulic hose manufacturers estimate that 80% of hose failures are attributable to external physical damage through twisting, pulling, kinking, crushing or abrasion of the hose. Abrasion caused by hoses rubbing against each other or surrounding surfaces is the most common type of damage.  In the photos below you can see examples showing why hoses can fail prematurely.  The first photo shows several problems with twisting, unprotected hose and poor routing.  The second photo shows an example of poor routing resulting in incorrect bend radius which is causing this hose to fail prematurely.

Twisting a hydraulic hose in more than one plane results in twisting of its wire reinforcement. A twist of five degrees can reduce the service life of a high-pressure hydraulic hose by as much as 70% and a seven degree twist can result in a 90% reduction in service life.

Bolts and Guards

Bolts and Guards

Many downtime incidents on forestry equipment can be traced back to guards that came loose or fell off.  Understanding the reason why guards often come loose can help you understand how to prevent this from happening.  When a guard falls off it normally exposes a critical component that can cause or lead to a catastrophic failure of that important and expensive component.  Most guards are mounted with soft bolts.  Soft bolts allow the guards to receive wear and impacts without shearing the bolts off.  Soft bolts normally stretch without breaking but this also means that they will require maintenance.  Bolts in some guards that are taking impacts on a regular basis such as, harvester head or forwarder and skidder belly pans, may require tightening on a regular basis.  From continual tightening or removing and re-installing bolts they can become worn.  Soft bolts wear fast and therefore may need to be changed more often.  However, soft bolts will not wear the threads of the frame components as quickly as hard bolts.  Some think that using hard bolts should be better because they are stronger.  Not necessarily, hard bolts will not stretch and can wear component threads and are very prone to shearing off.  Washers are the key to keeping bolts tight.  When both impact and vibration are present, two piece Nordlock or similar type washers are normally the most effective.

Best practice is to check guard bolts often, change bolts that are worn and replace washers that are missing.

Electrical

Electrical

Electrical wiring on equipment can get damaged or malfunction due to damage, moisture, elevated resistance or poor connections.  Understanding the reason why issues with electrical wiring happen can help you understand how to prevent this from occurring.  This spring when your machines are not working during breakup it is a great time to go over your electrical wiring from top to bottom.  Any wires that are damaged should be replaced.  Wires are often repaired by twisting the wires together and taping them with electrical tape.  Problem with this is that without the proper insulation moisture can eventually enter the spliced area and cause corrosion or a poor splice can raise the level of resistance and eventually cause the connection to fail.  If resistance gets high enough the circuit can overheat or cause the fuse for the circuit to blow.

If you have problems with blowing a fuse NEVER replace the fuse with one of a higher amperage or substitute the fuse with a solid conductive material.

When troubleshooting an electrical problem always test the circuit on the ground side of the circuit as well the power side.  Poor grounds have been the cause of many malfunctioning circuits.  A good habit is to remove the fastener connecting the ground wires or straps to the machine frame and clean the connection with a wire brush at least once a year.  Poor grounds can cause a variety of strange things to happen with the electrical system.  One common problem is premature failure of light bulbs.

Below on the left you can see some repaired wires that can cause problems.  On the right you can see an example of corrosion.