What is the length of the path of contact ?
In an involute gear, the portion of the line of action that sees actual contact is its length of the path of contact.
As shown below, a and b are the points where the tooth tip circle starts to intersect the line of action and where the contact ends respectively.
This distance ab is the length of the path of contact.
As shown in the formula below, if the length of the path of contact is divided by the base pitch, the resulting value is the contact ratio ε.
ε = the length of the path of contact / base pitch
It should be noted that in the diagram below, the length of the path of contact from the start of contact to the pitch point (the length of the path of contact from a to P) is called the length of the approaching path of contact while the length from the pitch point to the end of engagement (P to b on the path of contact) is called the length of the recess path of contact.
相关链接 - 啮合线长度