MODULE DIFFERENCES IN GEAR TRAIN

[Frankieboy]

Hi!

Question:

What problems will we suffer of in case we combine 4 gears in a gear train (gear 1 drives gear 2, gear 2 drives gear 3, gear 3 drives gear 4) in case transversal modules are not the same?

General data:
Pitch: 10 mm
Normal module: 2.75

Gear 1 transversal module: 3.16756
Gear 2 transversal module: 3.18120
Gear 3 transversal module: 3.18120
Gear 4 transversal module: 3.16756.

This indicates the pitch angle of the gears are not the same as well.

Frankieboy

 

[Spurs]

Frankie

The normal base pitches must be equal between any two gears in mesh or they will not mesh with conjugate action.

If you can design two gears with different modiles and pressure angles such that the normal base pitches are identical - you can be sucessful

But

this is extremely difficult to do

ereit@rogers.com

 

[Frankieboy]

Hi Spurs,

the reason I ask this is because we've got a machine suffering of problems. It could be this is caused by the differences in module as described. Problems are:

Low speed (circumferential speed of the gears)up to 100 m/min --> rumbling sound

High speed (circum ..) > 100 m/min --> loud resounding sound and vibrations. Vibrations getting smaller once going faster than 180 m/min.

There are some other things wrong as well, but this is defenately not right. I think we've to replace the gears - am I right?

Frankieboy

 

[Spurs]

Frankieboy

I cannot conclusively say what your problem is from what you have said. It would require much more study to understand what is going on. If you need assistance, contact me at my email address above.

 

[diamondjim]

Frankieboy,
Are you certain that the modules
are correct and that they do not
have profile shifts giving you
false base pitches for these
gears? If they were specified
as you have listed, you should have
had problems from day 1 assuming
these were on parallel axis.

 

[Spurs]

I agree Diamondjim - but he should be able to measure base pitch directly to verify if the different gears match.

 

[Frankieboy]

Hi Diamondjim, Spurs,

I checked data again and found out pitch diameters are really as such they have to result in different angles. I'll contact my gear manufacturer in order to discuss the issue.


We already suffer of problems from the first day we were really able to run the machine decently. As written, rubling noice at low speed and resounding metal-like sound at higher speed. I made some small calculations and found out that in case a teeth at one one side of the first - second gear contacts the teeth of the other gear, there is a play of 0.6 mm between the teeth at the other side. For me, this is inacceptable.

I'm not able to measure at this moment, because I'm not available at the machine site (too far away).

Thanks for your comment.

Frankieboy