Gear Technology Magazine
www.geartechnology.com/articles/21128-line-of-action-concepts-calculations

Line of Action: Concepts & Calculations

January 1, 1993
In the past gear manufacturers have had to rely on hob manufacturers' inspection of individual elements of a hob, such as lead, involute, spacing, and runout. These did not always guarantee correct gears, as contained elements may cause a hob to produce gears beyond tolerance limits.