By Brad Murphy
Tree care equipment is tough stuff. Whether it’s a chipper, stump grinder or log splitter, these pieces are built durable and designed to handle the most demanding conditions. And it only makes sense that the better it’s built, the more reliable it will be. Yet it’s amazing that more customers don’t always pay attention to the most crucial components when choosing equipment — the engine.
All tree care professionals ultimately want the best piece of equipment that will last, not just through the end of the day, but for years to come. After all, productivity and equipment return on investment (ROI) are among the most important factors to any contractor. Sure, it’s necessary to look at factors such as a grinder’s teeth, a splitter’s wedge height, or a chipper’s knives when making the final purchasing decision. But few stop to consider the driving force behind the equipment. Choosing the right engine is crucial when selecting a piece of outdoor power equipment, both for performance and efficiency on the jobsite, as well as the overall bottom line and ROI.
These days, most manufacturers offer equipment with multiple engine options, and dealers and rental centers are taking the initiative to stock more than one brand of engine. Although options are great, they can also complicate things, leaving customers to decide on the engine choice that best meets their needs. But it doesn’t have to be complicated. Selecting the best engine simply comes down to knowing what features to look for. Factors such as design technology, quality components and added features will all add up to a better engine — and a more reliable, more powerful piece of equipment.
Most engines used in large tree care equipment will offer one of two designs — pushrod overhead valve (OHV) or overhead camshaft (OHC). Both offer benefits and advanced features, but each operates differently and will affect the equipment’s performance.
Pushrod OHV engines boast the ability to provide exceptional power and performance in a small package by offering an efficiently configured combustion chamber. The pushrod OHV design has been popular since the mid ‘80s in general-purpose air-cooled engines, and has proven itself as a successful and durable design. But just like cell phones, computers and automobiles, technology continues to advance. And another design has been picking up popularity in more recent years.
Some engine manufacturers have begun to offer OHC technology on smaller engines used for various pieces of outdoor power equipment, including landscape, garden and tree care products. This type of configuration places the camshaft within the cylinder head, above the combustion chamber, allowing the valves to be driven in a more direct manner compared with OHV designs. The placement also eliminates the need for pushrods, the driving force in OHV engines. In a nutshell, the OHC engine is carefully designed to run at an optimal level at all times — meaning the equipment that it is powering will too.
OHC engines are easy starting, produce less noise, and offer superior power compared with other similar-class engines. They also lower fuel consumption and reduce emissions — crucial for meeting strict EPA regulations. Some OHC engines also incorporate a hemispherical combustion chamber, which is carefully designed to achieve maximum combustion and allow the engine to utilize a higher compression ratio, resulting in more power and torque.
Regardless of valve or camshaft design, a good quality engine will go a long way in enhancing equipment performance and increasing efficiency on the jobsite. Some engine manufacturers further optimize engine performance by customizing engines for certain pieces of equipment.
Tree care equipment is like professional baseball — it doesn’t have much of an “off-season,” nor does it get a very long winter break. Aside from maybe a month or two during the winter, this equipment typically runs year-round, and needs an engine that can handle varying temperatures and changing weather conditions. Better yet, some engines are actually designed for multi-season operation.
At the peak of summer, most areas of the country top out at well over 100 degrees Fahrenheit. Overheating is among the leading causes of engine failure. When the engine goes down, so does the equipment. An engine lacking adequate cooling won’t last more than a few minutes in the scorching heat, so it’s crucial to look for a design that offers advanced cooling features. Some manufacturers have designed engines to allow 360-degree airflow around both the exhaust and intake valve stem areas. This provides much-needed cooling and, when combined with other features like heat dissipation fins, enables optimal operation from morning to night.
On the other end of the thermometer, an engine needs to be able to handle cold, damp weather as well. Most contractors don’t have the luxury of taking time off when the mercury dips — and their equipment doesn’t either. Because many parts of the country experience freezing temperatures, damp conditions and even snow, engines also must be able to run well in these types of environments.
Some engines include special features designed to direct heat from the cylinder head back to the carburetor to keep it warm. This ensures ideal engine temperature and aids in easy starting. These types of features often direct heat into the air cleaner system as well, eliminating potential ice build-up and airflow restriction. Additionally, many engines offer strategically placed guards designed to prevent snow and ice from entering the engine and freezing up, causing damage to the governor system, vital controls and linkages. On their own or in combination, these types of features will help optimize engine performance, as well as ensure easy starting — crucial in getting the equipment up and running on chilly days.
Temperature, though important, is only one part of the equation. Another factor that must be taken into consideration when choosing an engine is noise level.
Keep it down!
Every tree care company and municipality that has ever served or operated near residential areas knows the importance of quiet equipment. It’s more than wanting to appease homeowners. Some areas actually limit the decibel level equipment can produce, and a quieter engine will go a long way in keeping the peace. Although most tree care equipment is fairly noisy on its own, an engine that reduces sound will be important on quieter pieces of equipment such as log splitters.
OHC technology reduces noise levels by limiting the number of moving parts. As a result, OHC engines produce less noise than similar OHV units. In fact, some manufactures have engineered models to have up to 33 percent fewer moving valve train parts than similar OHV styles.
Additionally, certain features will encourage reduction in sound levels. Specially designed mufflers provide further sound reduction than a standard engine muffler, and pairing with OHC features, the combination of these two can significantly reduce noise levels.
From optimal uptime and environmentally friendly operation to reduced noise levels and easy starting, there are several factors to consider when choosing an engine. But what makes an engine valuable boils down to more than just engineering and design. Both the materials it’s constructed of and added features will contribute greatly to enhanced durability and reliability.
It’s what you’re made of
These days, more and more plastic is being introduced into internal engine components. Although fine for lighter-duty engines, it’s very important to have precision steel parts in commercial engines. Piston rings, crankshafts, timing chains, rocker arms and cam lobes are all components that should be constructed of steel, as the wear characteristics are much better than those of engines that are manufactured with plastic components.
It will also be beneficial to look for a cast-iron cylinder liner. Most outdoor power equipment engine blocks are made from aluminum, a very soft material in contrast to the steel or chrome rings on the pistons. This variation in hardness causes the piston rings to quickly wear away the aluminum cylinder walls. As the cylinder walls wear down, compression is lost and, ultimately, the engine no longer produces the required amount of power to properly run the equipment. To avoid this problem, look for an engine with a cast-iron cylinder liner. Because this material is much harder than aluminum, cylinders with a cast-iron lining wear much better, leading to increased engine life.
Also important in a quality engine is ball-bearing support of the crankshaft. Ball bearings reduce friction, resulting in an increase of power delivery to the crankshaft. Additionally, ball-bearing support prevents problems caused by placing a crankshaft directly on an aluminum housing. Because aluminum is a soft material, the crankshaft will wear away at the housing and eventually cause oil leaks during operation.
Looking for these types of quality components will increase overall durability and reduce service requirements — along with downtime. Also crucial to engine life are added features — the extra, bonus items that seem minor on their own, but truly add up.
Two main factors will kill and engine: heat, mentioned earlier, and dirt. If dirt gets into the engine, it can infiltrate the oil and cause additional wear on the connecting rod and crankshaft. This is why a high-quality air cleaner system is essential to an engine’s operation and longevity. An efficient air cleaner will reduce wear on the valves and rings by preventing dirt and other harmful particles from entering the engine. An air cleaner with a dual element and small micron size should be selected to ensure optimum protection against fine particles of dirt.
The air filter is an important part of the air cleaner system, and some manufacturers are now offering high-quality washable filters. Generally speaking, a washable filter is typically more effective at trapping and holding dirt, ultimately leading to a longer engine life. As an added benefit, these easy-to-clean filters are reusable, so waste and replacement costs are significantly reduced.
A durable, high-strength recoil guard is also a beneficial feature. A guard, typically made from a durable yet lightweight poly material, will protect the engine’s recoil from damage incurred during transfer and on the jobsite. A recoil that hasn’t been damaged will start much easier and save the operator from repair or full replacement costs.
Another feature to look for in a high-quality engine is a low-oil sensor. If an operator allows the oil to drop below a safe range, the sensor will ground out the ignition and stop the engine before damage occurs. In a world filled with too much to do, and not enough time to do it, this feature can be a lifesaver for busy contractors who may overlook basic maintenance items such as checking the engine’s oil.
Finally, choosing and engine from a reputable manufacturer with a good warranty program and service network will ensure that any problems are handled quickly and professionally. After all, who has time to waste chasing down a service provider or arguing about a warranty claim?
On the surface, it might seem complicated to know which engine is the best choice for a piece of equipment. But simply taking the time to do a little homework and know which features to look for will ensure every contractor gets the most out of outdoor power equipment — both in terms of performance and ROI.
Brad Murphy is vice-president, sales and marketing, at Subaru.