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Helical Gears
Click on a link below to learn more about the different types of helical gears CMG manufactures.
Helical Gear
Double Helical Gear
Herringbone Gear
Internal Helical Gear
Helical Gear
A helical gear, sometimes referred to as a spiral gear, is a gear designed to provide uniform rotation on an axis perpendicular to the transverse plane, however the teeth are at an angle to the axis of rotation. A helical gear can be a cylindrical shape in itself or part of a shaft as a helical geared shaft. Advantages to helical gears include having more teeth in contact for a greater contact ratio and helical gears are generally quieter. A disadvantage is that a helical gear causes axial thrust.CMG utilizes the hobbing process to manufacture helical gears up to 16” in diameter. The range of diametral pitches we typically have tooling for is from 3DP to 32DP (.5 Mod to 10 Mod metric) and the length of the gear face not to exceed 12.0”. CMG is limited to a range of +/- 45 degree helix angles. CMG, depending on pitch and material, can obtain an AGMA 10 rating on helical gears that are not heat treated. CMG can also gear grind the tooth profile and achieve up to AGMA 13 on helical gears up to 400mm(15.75”) in diameter on gears that have been heat treated. CMG can also hob helical gears on shafts. Our capacity for helical geared shafts depends on many geometric parameters inherit to the design of the shaft, so a print is typically needed to determine the feasibility of it. A larger size for us typically involves a journal of no greater than 4.0” in diameter and a length of no greater that 40.0”.
CMG has the ability to reverse engineer damaged sets for replacement.
Double Helical Gear
Double helical gears are two helical gears of opposite hands on a common gear blank with a space between the meeting of the two gears. The advantage of a double helical gear is that it eliminates axial thrust.CMG can manufacture a double helical gear. CMG would only be able to make this type of gear out of one piece if the clearance in the space between the meeting of the two gears allowed for appropriate hob clearance. Otherwise the gear would have to be constructed out of two pieces. This makes this type of gear costly due to fixturing and line up requirements. CMG does not typically encounter this type of gear.
Herringbone Gear
Herringbone gears are similar to the double helical gear in that it is two helical gears of opposite hands, however in this case the two gears meet (no space between them) at the apex. A disadvantage of herringbone gears is the cost due to special gear shaping equipment and special cutting tools.CMG does not produce herringbone gears due to the cost of special equipment and lack of demand in our customer base.
Internal Helical Gear
Internal helical gears are similar to internal spur gears in that the teeth are on the inside of the blank, but the internal helical gears teeth are at an angle to either the left or right hand and mate with the same hand external gear. Internal helical gears require special guides or new generation guideless shaper machines and special cutters.CMG has been involved with internal helical gears when the customer has been able to provide guides and cutters compatible with our gear shaping equipment. CMG does not typically produce this type of gear because of that constraint.
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