The chain brake lever is activated by your left wrist when the saw tip rotates toward you. Note the tool-free tensioning mechanisms.
A trend in chainsaws of all sorts is providing tool-free chain adjustment, a feature found on the Craftsman models, the Remington, and the Stihl MSE 180. This is supposed to allow you to more easily, and therefore more frequently, optimize your chain tension during a job. In reality, oil and sawdust can gunk up the works and make the smaller tensioning wheels difficult to turn with your fingers. Tool tensioning is always reliable but slightly less convenient. It's really a toss-up.
A more-established trend is the use of automatic oilers for lubricating the bar and chain. This feature is offered on all but the oldest tool, the Makita 5012B, which has been sold with a manual oiler for almost 30 years. Many find this to be a benefit, however, as it is the only model that lets the user decide when to use oil more sparingly, such as to avoid staining a nearly finished wood surface. The automatic oilers are non-adjustable and, when working properly, are constantly releasing a small stream of oil that can eventually make its way off the tip of the saw as a fine spray. In fact, looking for this spray stain with the saw running without a load is how you test if your oiler is working.
Another common chainsaw feature are spikes, called dogs, on the front of the saw body that provide a fulcrum for the user to lever against to apply a downward force without having to push down too hard. Using the dogs allows more stability and therefore more safety. Dogs on the test models ranged from small plastic bumps to jagged steel teeth. Most were able to grip rough wood well enough, and the more aggressive grippers were more likely to leave marks on the workpiece.
One feature worth mentioning is the coast-down brake on the Stihl MSE 180 that stops the chain when the trigger is released. This feature, while welcome on all types of saws, was especially handy on a chainsaw. Not only could I lift the bar out of a kerf or safely set the saw down immediately after a cut, but when cutting to a marked depth line, the brake kept the saw from over-cutting.
A typical sprocket nose bar runs with much less friction and heat. It should be kept lubricated via its small grease port.
Kickback, which occurs when the top half of the bar tip contacts an object and the chain's rotating force literally kicks the bar back and upward toward the operator, is the No. 1 chainsaw safety hazard, so manufacturers incorporate a lot into their design features to reduce its potential.
To comply with UL standards, electric chainsaws have to meet a maximum kickback angle requirement adopted from gas chainsaw standards and feature a minimum of two other devices to reduce the potential for kickback injury. These include chain brakes, low kickback chain, reduced kickback bars, and tip guards. Most of the saws in this test have three devices; all come supplied with safety bars and chains, and all but the Makita 5012B and Remington have chain brakes. The Makita 5012B's third device is a tip guard. Only the Remington has the bare minimum two safety features.
Chain brakes serve to stop the chain and motor when part of your body contacts the guard lever adjacent to the front handle. Most are automatic brakes that also feature inertial activation of the brake lever without direct contact. The Craftsman 34107 and Milwaukee have non-automatic brakes. In my testing, only the Craftsman 34118, Husqvarna, and Stihl MSE 180 brakes activated readily by their inertia function.
The inline design of the Husqvarna saw applies your weight directly over the bar, providing more control.
Remember, like any other serious power tool, chainsaw use requires safe user habits regardless of how many safety devices are built into your saw. Recent figures show that at least 36,000 chainsaw injuries occur each year in the U.S. alone and that the average injury requires 110 stitches! Work carefully and respect the saw and some of this year's 4 million stitches can be prevented.
Another UL requirement is the always-annoying, 1-foot, shrouded-end pigtail cord found on outdoor power equipment. An interview with UL explained its necessity: Basically, the shroud is to keep the conductors from contacting anything wet, and its length (less than 18 inches) keeps the receptacle connection up off the ground. Since you usually use an extension cord with these tools outdoors anyway, two added benefits include no downtime or tool repair needed if the cord is accidentally cut during use (because it will be the extension cord), and the fact that the cord connection is within reach and allows you to pull on the extension cord directly when dragging it around rather than tugging the cord connection loose.