Comments on: Camshaft drive gears http://www.ret-monitor.com/articles/1140/camshaft-drive-gears/ Specific mission-critical info for professionals Fri, 18 May 2012 08:59:38 +0000 http://wordpress.org/?v=2.7.1 hourly 1 By: Terry http://www.ret-monitor.com/articles/1140/camshaft-drive-gears/comment-page-1/#comment-6150 Terry Mon, 17 Jan 2011 05:39:15 +0000 http://www.ret-monitor.com/articles/1140/camshaft-drive-gears/#comment-6150 Making a gear integral with the crank is definitely lighter and more reliable. But if the gear needs to be located close to the main journal, it cannot be finish ground unless the root diameter is larger than the adjacent journal. Making the crank gear with a small diameter is usually beneficial, due to the fact that a 4-stroke cam drive requires a 2:1 reduction. Keeping the crank gear small negates the need for compound idlers, and keeps the cam gear small also. A nitrided gear will have less heat treat distortion than a carburized gear. But it will also have less case thickness, and less contact load capability. The carburized gear will need a finish grind operation, while the nitride gear may only require a rotary honing operation for clean up. Making a gear integral with the crank is definitely lighter and more reliable. But if the gear needs to be located close to the main journal, it cannot be finish ground unless the root diameter is larger than the adjacent journal. Making the crank gear with a small diameter is usually beneficial, due to the fact that a 4-stroke cam drive requires a 2:1 reduction. Keeping the crank gear small negates the need for compound idlers, and keeps the cam gear small also.

A nitrided gear will have less heat treat distortion than a carburized gear. But it will also have less case thickness, and less contact load capability. The carburized gear will need a finish grind operation, while the nitride gear may only require a rotary honing operation for clean up.

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