Tree work words: saw chain, bar, fuel and batteries

Chain, bar, fuel and battery words differ between makers and between countries, and the pages that use them rarely define them. This page lists what each named source says a word means, so a term on a parts counter, a fuel can or a battery notice can be matched to a written definition. It describes words. It is not a guide to fitting, filing, mixing or charging.

Every meaning is written in our own words from the page named in its row. A word that none of those pages defines is not listed. The maker pages are cited for the words they print, and they are statements by makers about their own products. The wider A to Z list is the tree work glossary, and the saw words for felling and hand aids are in tree work words: saws and cutting.

Chain and cutters

Term	Meaning and source
Cutter	The part of the chain that cuts the wood. It is one of four basic components of a saw chain. Source: Chain maker's page on saw chain terminology
Rivet	One of the small metal pieces that hold the chain together. Source: Chain maker's page on saw chain terminology
Drive link	The part that passes motion and power from the saw to the cutters. Another page from the same maker adds that it carries the chain along the bar rails and around the sprocket. Source: Chain maker's pages on saw chain terminology and replacing chainsaw chain
Tie strap	The part that keeps the chain stable and in place while it runs. Source: Chain maker's page on saw chain terminology
Parts of a cutter	The maker names the top plate, cutting corner, slide plate, gullet, depth gauge, heel, rivet hole and toe. It describes the gullet as the recessed area between cutting teeth that helps move chips out. Source: Chain maker's page on saw chain terminology
Depth gauge	The part of the cutter that controls how much wood each pass removes, in the chain maker's words. The Canadian fact sheet names a flat file for adjusting it and a round file for the cutters. The HSE leaflet lists depth gauge profiles in its maintenance checklist. Source: Chain maker's page on saw chain terminology; CCOHS fact sheet on maintenance and service; HSE leaflet AFAG308
Gauge	The thickness of the drive link where it sits in the guide bar groove. The chain's gauge and the bar's gauge match. The maker lists .043, .050, .058 and .063 inch and says a worn chain can be hard to measure, so the figure stamped on the drive link is the reference. Source: Chain maker's page on saw chain terminology
Pitch	The size of the chain: the distance between any three consecutive rivets divided by two. The maker lists 1/4 inch as its smallest and 3/4 inch as its largest, and says the drive sprocket and any nose sprocket have the same pitch as the chain. Source: Chain maker's page on saw chain terminology
Kerf	The width of material the saw removes when it cuts. Source: Chain maker's page on saw chain terminology
Chisel cutter	A square cutter. In the chain maker's words it cuts a full-width kerf with every pass. A maker's product page lists a full-chisel chain with the profile entry Chisel. Source: Chain maker's page on saw chain terminology; maker's full-chisel chain product page
Rounded cutter	A cutter that has to re-cut the end grain several times until the full width of the kerf is reached, as the chain maker explains why chisel chain cuts faster. Source: Chain maker's page on saw chain terminology
Semi-chisel	A cutter profile. One maker's product page lists a chain with the profile Semi chisel, and the chain maker's page names semi-chisel as one of its cutter types. Source: Maker's semi-chisel chain product page; chain maker's page on saw chain terminology
Chipper, chamfer-chisel, micro-chisel	Three more cutter types the chain maker names in its list beside chisel and semi-chisel. The text of the page gives no further description of them. Source: Chain maker's page on saw chain terminology
Low profile full chisel	A saw chain described this way in one maker's UK range of chains and guide bars. Source: Saw maker's UK page on saw chains and guide bars
Sequence (standard, semi-skip, skip)	How the cutters are laid out along the chain. The chain maker says standard suits general cutting, and semi-skip and skip suit work where chip clearance matters, such as larger diameter wood. Source: Chain maker's page on saw chain terminology
Low kickback and reduced kickback chain	Two kinds of kickback-reducing device the Canadian fact sheet lists with the chain brake. It says such devices are designed for the saw in use, meet standards such as CSA Z62.3-11 (R2021) or ANSI B175.1-2021, and reduce kickback but do not prevent it. Source: CCOHS fact sheet on kickback
Wear marker	A mark on every tooth of the maker's chain, shown in red on its page. Source: Saw maker's UK page on when to replace a chain, sprocket or guide bar

Bar, sprocket and length

Term	Meaning and source
Rails and groove	The rails are the sides of the guide bar. The groove is the room between them where the drive links sit, and the maker says wear on the rails lowers the groove depth. Source: Saw maker's UK page on when to replace a chain, sprocket or guide bar
Control gauge	A maker's tool that monitors the drive link thickness and the groove width of the guide bar, and is also used to check rim and spur sprockets. Source: Saw maker's UK page on when to replace a chain, sprocket or guide bar
Sprocket	The part behind the sprocket cover that drives the chain. The maker names rim and spur sprockets. Source: Saw maker's UK page on when to replace a chain, sprocket or guide bar; CCOHS fact sheet on maintenance and service
Called length (cutting length)	The length of a guide bar measured from the front of the saw to the tip of the bar, rounded to the nearest inch. It differs from the overall length. Source: Chain maker's page on replacing chainsaw chain
Drive link count	The way chain length is measured: the number of drive links, which has to match the guide bar. The maker says the count follows the chain type designation in the part number. Source: Chain maker's page on replacing chainsaw chain
Chain-oil portal	The opening that delivers oil to the cutting chain. The Canadian fact sheet says sawdust can block it. The saw maker calls the opening the oil inlet hole in the guide bar. Source: CCOHS fact sheet on maintenance and service; saw maker's UK page on when to replace a chain, sprocket or guide bar

Fuel and oil

Term	Meaning and source
Fuel mix (two-stroke mix)	The petrol and two-stroke engine oil blend a petrol chainsaw runs on. Source: Saw maker's UK page on chainsaw fuel mix
Mix ratio	The parts of petrol to one part of oil. The maker states 50 to 1 for its own tools, which is 100 ml of oil in 5 litres of petrol, and says a wrong ratio can seriously damage a saw. The Canadian fact sheet says too much oil makes a saw run dirty and too little damages engine parts, and refers to the maker's recommendation. Source: Saw maker's UK page on chainsaw fuel mix; CCOHS fact sheet on maintenance and service
Ready-mixed fuel	Petrol already blended with two-stroke oil. The safety forum bulletin describes alkylate petrol sold ready mixed with biodegradable oil, and the saw maker describes its own ready-mixed fuel as having a long shelf life. Source: Safety forum bulletin 03.18; saw maker's UK page on chainsaw fuel mix
E5 and E10	Petrol with up to 5 percent or up to 10 percent ethanol. The saw maker says both are suitable for its chainsaws. Source: Saw maker's UK page on chainsaw fuel mix
Alkylate petrol	A petrol the safety forum bulletin says was introduced in Scandinavia in 1988 and does not contain benzene. A field study measured exhaust exposure with two alkylate fuels against a normal petrol mix. Source: Safety forum bulletin 03.18; Field study: 2016 chainsaw exhaust study
Fuel gum	A resinous residue left behind when fuel evaporates during long storage. The maker says it can leave deposits in the combustion chamber and block nozzles and filters. Source: Saw maker's UK page on chainsaw fuel mix
Fuel separation	In mix containing ethanol, oil and petrol separate quite quickly as moisture binds to the ethanol and sinks. The maker gives this as the reason it names 30 days for a mix made by the user. Source: Saw maker's UK page on chainsaw fuel mix
Bar and chain oil	The oil that lubricates the chain and bar. The Canadian fact sheet refers to chain saw oil of the correct grade and type, and a maker's product page names a bar and chain oil with anti-wear additives. Source: CCOHS fact sheet on maintenance and service; maker's bar and chain oil product page
Tackifier	An additive in a maker's bar and chain oil. The page says it keeps the lubrication on the cutting equipment and makes longer lasting strings of oil. Source: Maker's bar and chain oil product page
Biodegradable chain oil	A vegetable-based oil. One maker states that its product biodegrades within 28 days. Another maker's storage page says this kind of oil can gum in the tank. Source: Maker's biodegradable oil product page; saw maker's UK page on chainsaw storage

Batteries

Term	Meaning and source
Lithium-ion battery	One or more lithium cells connected together. Each cell has a positive electrode, a negative electrode, a separator and an electrolyte solution. OSHA says these batteries are usually rechargeable and power devices including power tools. Source: OSHA bulletin SHIB 06-20-2019 and OSHA fact sheet FS-4480
Lithium-metal battery	A battery with lithium-metal electrodes that is generally not rechargeable. Source: OSHA bulletin SHIB 06-20-2019
Thermal runaway	A chain reaction in which heat released by one failing cell damages nearby cells. OSHA lists a rise in battery temperature, venting of gas, vapor or smoke, and fire as signs. Source: OSHA bulletin SHIB 06-20-2019; OSHA fact sheet FS-4480
NRTL and UL 2054	OSHA gives UL 2054 as an example of a test standard for lithium batteries, and says certification by a Nationally Recognized Testing Laboratory (NRTL) applies where applicable. Source: OSHA bulletin SHIB 06-20-2019

Reading these sources

Most chain words come from two makers' pages and the Canadian fact sheet, so the same word can carry another meaning at a different maker. Fuel words come from one saw maker's UK page, a safety forum bulletin and a university field study. Battery words come from OSHA. The page about pitch, gauge and file size by maker sets out the maker figures for chain, and the page on battery saws and lithium-ion batteries carries the OSHA and EPA statements in full.

Contains public sector information published by the Health and Safety Executive and licensed under the Open Government Licence v3.0. The wording above is ours.