Grooves on a gear Grooves on a gear spigor (Mechanical) (OP) 24 Jul 15 06:52 I have seen some gears for the agriculture machines having one or more shallow grooves on the outer dia. http://files.engineering.com/getfile.aspx?folder=9... What are these grooves for? Thank you in advance for your input. http://files.engineering.com/getfile.aspx?folder=900bc5de-f941-406e-8ce1-30 RE: Grooves on a gear 3 tbuelna (Aerospace) 25 Jul 15 00:40 Those are identification markings (one groove, two grooves, three grooves, etc) indicating what application the gear is used for. Sometimes a basic production transmission design will use a slightly different gear set for specific applications, with variations in tooth geometry (pressure angle, addendum modification, etc) made to optimize efficiency, performance, fatigue life, etc. All of the gear variants might use the same number of teeth and have a very similar visual appearance, but each would only mesh properly with the correct mating gear. The reason for using a series of grooves on the tooth top lands is because it provides a quick and fool-proof method to visually confirm the correct gears are being used. Back in the olden days, before the availability of laser marking systems, turning a set of grooves in the OD of the gear blank was a cheap way to permanently ID the part. Here's a related link.