Can gears mesh with different operating pressure angle?

[tarata88]

Hi, I have a question regarding gear mesh. Can anyone please enlight me, thank you.
Considering a gear train system, for ex. 3 gears. If the first two gears are designed with profile shift, making an operating pressure angle, say 30deg, differed from the standard pressure angle 20deg(from gear cutter). Is it required that the rest of the gears in the system, for ex. the 3rd gear, be designed with the same operating pressure angle(30deg in this ex.)? or the rest of the gears can be designed with any arbitary working pressure angles as long as all the gears in the gear train system have the same base pitch for all gear to mesh?

 

[spigor]

A single involute gear can not be designed with any operating pressure angle, because the latter is always created in the meshing of two gears. One gear can be meshed with multiple gears with a different operating pressure angle in each meshing. Both gears in such a pair must have equal normal base pitches, and the contact ratios should be greater than one.

 

[tarata88]

Thank you for you input, I think I understand more.
It means that, the operating pressure angle is not a property of an involute gear itself, rather a calculated value at the status (mating position) when two gears are in mesh. The mating center distance of two gears can be changed/adjusted and in turn the operating pressure angle changed accordingly at the new position.
So as long as any two gears have the same base pitches they can be meshed, and the operating pressure angle will change based on the center distance.
Please correct me if I'm wrong, thank you~

 

[mfgenggear]

OP
Yes if all gears have the same base pitch
They will mesh, how ever it is not good practice. It's recommended all gear have the same modual or diametral pitch and pressure angle. All base pitch gear must pass an involure verification. And must still meet the AGMA or ISO quality requirements.

Engineers will use non standard designs to try and prevent other companies from coping their design. But with the new gear gear inspection , unknown gear software is it is easier to decipher. Reverse engineer.

An other reason a base pitch is used to
Alter the profile shift and prevent sharp major diameter on external gear.

 

[mfgenggear]

Op
Center distance will or can be used to control center backlash , it will adjust the operating pressure angle but all gears require the same pressure angle during manufacture.

 

[spigor]

Thank you for you input, I think I understand more.
It means that, the operating pressure angle is not a property of an involute gear itself, rather a calculated value at the status (mating position) when two gears are in mesh. The mating center distance of two gears can be changed/adjusted and in turn the operating pressure angle changed accordingly at the new position.
So as long as any two gears have the same base pitches they can be meshed, and the operating pressure angle will change based on the center distance.
Please correct me if I'm wrong, thank you~

That's right. There are some further details like contact ratios and shapes of fillet sections, but the general idea is this.

 

[tarata88]

Appreciated for all the replies, thank you~
There is so much too learn, every type of gears has its own subject.

 

[mfgenggear]

Op
There are some very good books to read. Then study the AGMA. For modern techniques.
Dudley vogal, Buckingham Shigleys.
Look at old you tube videos made by fellows, the art of generating gears.