Equipment failure can cost thousands in repair bills (or replacement costs), not to mention the lost work. Proper maintenance plays a critical role in keeping your equipment in good working order and helping to extend its life. Let’s take a look at proper maintenance procedures for two of the most important machines for tree care pros: chippers and aerial lifts.


At the heart of every tree cutting operation is the wood chipper. Its steady whine is familiar to everyone, and when that unit goes down unexpectedly and the noise stops, profits stop. With proper maintenance and inspection your chipper will provide years of faithful service, paying for itself multiple times. A chipper with dull blades or a badly adjusted bed knife will not only produce unsightly chips, but will also cost you extra money in fuel and excess labor hours.

On the road

If the chipper can’t attach to the truck, it stays at the yard, so the hitch is first on our list of items to inspect. Be sure that the hitch itself is not damaged and the latching mechanism is in proper working order with all the pins and clips needed. Homemade modifications have no place on a hitch latch. Check the safety chains for damage, make sure the hooks are in good shape and have safety clips still attached. Make sure they are the right length and are not dragging on the ground.

Check the trailer plug harness for damaged or exposed conductors. Plug it in and have someone check the lights for proper operation. Be sure the license plate is in good, clean condition. Traffic stops by law enforcement average 20 minutes. Check the lug nuts and tires for inflation, condition and wear. Keep the bearings well greased. Check the oil and fuel and note the date last serviced.

At the job site

Chock the wheels and set up your work perimeter and signage as needed. Put on your protective gear. Turn on your safety lights. Identify car and pedestrian traffic routes. Before operating the unit, thoroughly check the exterior for damage and missing parts such as guards, covers and hardware. Chippers have extremely fast-moving parts, so proper protection from the moving parts is critical. Maintain the safety decals. Be sure that the muffler, exhaust guard and spark arrester are in place and in good condition. Operate the clutch system without the machine running to be sure it is free. Check the discharge chute to see that it’s rotating freely. Make sure that the safety bar at the feed entrance operates freely.

Learn the manual, as different chippers have different procedures for operation and shutdown. There should be an operation checklist in the manual. Consider laminating it and making extra copies. Be sure all your operators have read the manual. Knowledge is safety.

In the garage

To determine when it’s time to service your chipper, you need to take multiple things into consideration. There will be an hour meter on the unit, and it’s highly important that the oil and filters on these units are changed regularly. The environment they work in is heavily laden with dust and is considered an extreme environment. Don’t forget the hydraulic oil filter. Hydraulic components are precise, delicate and expensive. Don’t wait until your unit stops chipping well to service it. Put it on a 100-hour schedule and don’t miss an interval. Check the belt and grease the bearings at the same time. Look the machine over thoroughly and talk to your operators. They will know if something is wrong.

Safety equipment

There are a variety of devices put in place on your chipper to keep the operator safe. These can include guards, shields, safety feed reversing bars, lights and decals. It is crucial not only for operators, but also for customer safety that these items are in proper operating condition. Keep the manual on the chipper and read it. Learn exactly what equipment your machine has and keep those items in proper operating condition.

The blades

Be aware that some manufacturers use special blades. Some have hardened blade edges and attachment hardware varies. Be sure to follow the manufacturer’s recommendations for replacement blade and hardware specifications. You can determine blade sharpness and bed knife adjustment by looking at the quality of the chips and by listening to and watching the operation of the unit. Sharp blades but a poorly adjusted bed knife will create long stringy chips. Dull blades will have broken, smashed looking chips. Both situations will reduce the efficiency of the unit.

Lock the unit out and open the cover and visually inspect the blades. Wear will be obvious. Rounded edges show normal wear, whereas chipped blades are a sign that the operator is not being careful with what goes into the chipper. Wear gloves and a long-sleeve shirt as the blades are very sharp and the sap can be irritating to the skin. The bed knife is a blunt block of hardened steel that the blades pass by. Its position is adjustable and also critical to the machine’s efficiency. Read the manual for proper bed knife measurements, and check the drum or wheel in multiple spots for adjustment as the blades can vary slightly.

Some companies invest in a blade-sharpening machine, some send them to a machine shop for sharpening, and some just replace them when worn. On some machines they are reversible, giving two cutting edges per blade. The bed knife edges, while blunt, also need attention, as the corners must be perfect 90-degree angles. Whatever your program, keeping a spare set of blades on the shelf is an advantage. Read the manual for blade torque specifications, because if a blade comes loose it is dangerous and destructive.

Who can maintain a chipper?

Anyone with the proper training and tools can do the work needed on a chipper, but be sure that they are trained and qualified. Chippers are complex machines, with parts moving at high velocity and at very close tolerances. They need to be serviced with care and attention to details such as interlocks and stop functions.

Don’t just let the tree crew work on it because there is no tree to work on that day. One loose bolt can literally destroy your entire chipper.

The manufacturer can provide you with a list of authorized repair facilities in your area. Some manufacturers have mobile service, so the work can be done at your location.

With proper care and common sense your wood chipper will continue to be the moneymaking workhorse it was engineered to be. Take the time to become familiar with the unit and its features and requirements. Be sure your operators are trained and understand the features before they operate the unit. Take the time to maintain your unit or have it done. The small amount of time and money spent upfront on maintenance is a great investment in the future of your operation.

Altec aerial lift

Photo: Altec

Aerial Lifts

Aerial work platforms, often known as bucket trucks, can be key to an arborist’s success and profitability. The key to the successful operation of an aerial work platform is maintenance and inspection. Through proper preventive maintenance, costly breakdowns can be virtually eliminated, and with a rigorous inspection program the level of safety for those working in and around the platform can be increased. Engineers spend countless hours trying to design and build the safest, most reliable equipment possible. Once it’s in your possession it’s up to you to keep the bar as high as the manufacturer has set it.

Preventive maintenance and inspection

Inside the operator’s manual or parts manual of most aerial platforms is a preventive maintenance and inspection checklist. This is created especially for the unit you are using, and is designed by the manufacturer to be part of a comprehensive inspection and maintenance program. The inspection intervals vary from unit to unit, as do the maintenance requirements, but all will be clearly explained in the manual. Any aerial equipment operator needs to be intimately familiar with the preventive maintenance and inspection checklist.

Frequent inspection and maintenance

Usually first on the list is a daily walk-around inspection. This is a mandatory preoperational checklist that needs to be completed before the unit is used for the day’s work. This can be done at the yard or at the job site. Doing it at the yard before the unit is taken on the road makes the most sense because your operator will already be doing a preoperational check on the truck itself, checking motor oil, tires, lights, etc. A log of this information should be kept, and any discrepancies need to be reported to a supervisor or fleet manager immediately so the situation can be remedied before a small issue turns into a lost time issue. If your operators could use aids on how to perform this inspection, the manufacturer can provide training and the necessary supporting information, such as forms and procedural instructions. This step needs to become habitual, just like checking the fuel level before leaving for a job site. It only takes minutes, and the value it adds to your workday can be tremendous.

Periodic inspection and maintenance

The preventive maintenance and inspection checklist will have sections with time frames of when certain procedures must be performed. This will be daily, monthly, six months, one year, two years, and four or five years, depending on the unit. These time frames usually will have an hour rating along with them, such as one month/85 hours. Again, it is important that you refer to the manual and checklists that come with your machine. The procedures required vary in their complexity, some being visual and operational; some will require special tools to measure and test individual components for wear and tolerance. At some of the longer intervals some larger components may need to be replaced or serviced such as leveling or drive cables. These components usually have manufacturing dates stamped in them so there is no question about their age. The manufacturer may also contact you when their system shows that these are due for replacement.

Dielectric testing

Some units are rated for dielectric strength, providing insulating features to help protect the operator from electric shock. These units require testing with a specialized dielectric testing machine. This test puts a large potential voltage at the platform of the unit while the machine is elevated, and then checks for leakage to the uninsulated section of the unit. This, along with good work practices and personal protective equipment, keep the operator safe from the voltage present at wires he may encounter while operating the unit. The insulated section of the boom is only one part of the equipment that is required to keep the operator safe from high-voltage lines. Special insulating gloves and protective items are needed as well as training.

Even if you don’t expect to encounter a situation with a high-voltage wire, if your unit is insulated, it must be dielectrically tested to pass its 12-month preventive maintenance inspection. Refer to the manual of your unit if you have any questions or contact the manufacturer.

What does the law require?

ANSI A92.2 clearly states that the unit must be maintained and inspected as the manufacturer recommends. Anything less is noncompliance. This means that a form that is created by anyone other than the manufacturer will not comply with this law unless it contains all of the items on the manufacturer’s form.

There are many third-party companies out there that will supply an “annual” for a discounted price. These “annuals” may provide some indication of the condition of the unit, but unless they comply fully with the manufacturer’s instructions on the inspection and maintenance of your unit, in the eyes of ANSI, you are in noncompliance.

If you have any questions about the law and what is involved, you can obtain a complete copy of the ANSI A92.2 on their website, or contact your manufacturer representative and they should be able to supply it for you.

In-house or subcontract?

Some equipment owners choose to do all the maintenance and inspection needed on their units in-house, while others have it done by the manufacturer or a third-party contractor.

The most important thing is to be sure that whoever is doing the work is qualified and is using the proper preventive maintenance and inspection checklist. Using factory service is an excellent value. It can save the owner money by increasing the reliability and safety of the unit, and often the manufacturer can do the job more cost effectively because of the increased efficiency that a manufacturer-trained technician has. You may be surprised at how affordable factory service can be, and in many instances you can have the service bundled with chassis requirements such as DOT or BIT inspections and chassis engine service to save even more money and reduce downtime by having everything done at once. The day you take to service your unit is a good day to have safety training for you operators.

Record keeping

Complete records must be maintained by the owner. These can be paper or electronic files. The person who does the work for you may keep copies and be able to provide a copy if needed, but it’s a good idea to maintain your own set of files on your machines.

A file folder with two subfolders, one for chassis BIT and DOT records and one for aerial unit records, would be sufficient. The main thing is to keep them – keep them accessible and keep them accurate. Your insurance company may require a copy of these documents as well. This will also pay off when you decide to replace your unit with a new one, as the value will be increased if you can provide documentation of proper maintenance.

OEM parts

According to ANSI A92.2, only parts that are identical in specification and function to the original aerial device parts or components or shall provide an equal or greater factor of safety can be used. Trying to find such parts and determine if they are truly identical in specifications can be difficult. When in doubt, use parts from the manufacturer. Bargains may be out there, such as off-brand filters where you can save a dollar or two, but the tolerances may not be the same.

Many parts installed on a unit are specifically designed and calibrated for use in this specific application. It is not worth risking all that you have riding in your bucket to save a small amount of money. A filter that fits but has a different micron rating will allow premature contamination of the hydraulic components in your system. An OEM hydraulic filter for a 55-foot arborist unit costs about $14. A main hydraulic valve, which can be damaged by unfiltered or improperly filtered oil, can cost $2,000 or $3,000 just for the part. It’s just not worth it.


Seasonal changes can affect the operation of your unit, especially in places with extremely cold temperatures. The hydraulic oil can thicken, which makes the components have to work harder and can reduce the efficiency of the unit. There are many ways to mitigate this: oil additives, tank heaters or simply running the tool circuit for a few minutes before operation. There are self-adhesive tank heaters that attach on the outside of the tank and require no additional plumbing. There are also devices that can plug into the tool circuit and estrict the flow of oil, heating it rapidly to operating temperature.

Units left to sit in the rain can develop rust and corrosion as well as moisture infiltration into the hydraulic oil. If possible, store the unit inside or under a cover. You may want to increase the greasing interval when operating in wet weather.

In the extreme heat, it’s important to keep the hydraulic oil tank full and free from external debris, as the tank acts as a cooling vessel. Debris buildup can insulate the tank, and low oil levels reduce the system’s ability to shed heat, potentially overheating the oil and damaging components.

Your mobile aerial work platform has been rigorously engineered to be a reliable workhorse providing years of trouble-free operation. By providing your machine with the maintenance outlined in the manual, you will ensure your aerial work platform is operational, profitable and safe.