Hi all,

My name is Jay and I am fairly new to the hole solidworks thing (including spur gears). I am trying to get some gearing to work, but the gears just wont line up.

The gears are evolvent module 4 and created by the toolbox (ANSI Metric > Power Transmissions > Gears > Spur Gear). The center distances are as many calculators give me, but the bottom gear (T3) just wont line up. What am I doing wrong?

Center distances:

T1 > T2	72,000mm
T2a > T2	101,823mm
T2 > T3	88,000mm
T1 > T3	122,689mm

Thanks in advance!

Cheers,
J

 

How made your calculation? Did you take in consideration the velocity of each spur gear, the material of them, and verify if the modules you chosen are right? Using solidworks toolbox is a handy way to design spur but after you calculate what you need for input in that toolbox. The info given is not useful - from my point of view - to find what is wrong in this design. From where start movement and with which speed? This is only for distraction or you want developed real engineering skills? If you want to understand how to do this I can help you but need to communicate more info about this mechanism.

 

Hi, try taking out one of the T2 gears and see what happens.

 

Your system will not work. If you need a drive as illustrated then gear T2A or T2B needs to be, say double width and the lower T3 off set to miss the other T2/3 gear.

 

You can do it with mitcalc, Mitcalc - addons for SW

 

The Arrangement will work , If you change T2a>T2 and T1>T3 to values which are dividable with 4.

 

Could you explain this? And is this even possible? I mean, when I change T2a>T2b, than the result T1>T3 will be a result of a calculation (triangle angles etc). If I set T1>T3 is will be vice versa...

Besides this I feel that there is a lot of space between the tooth.

 

You are on the right track. If T2a>T2b is changed the value of T1>T3 will change accordingly. This requires many iterations till the correct values are arrived. You can draw a quadrilateral with the corners as the centers of the gears and then start your calculations.
There is space between the tooth as you say, but the gears will not mesh as the interference is on the opposite flanks. From your fig., at the left hand mesh, the interference is on the right flank, and that on the right hand mesh it is on the left flank. The gears will mesh only if T2a>T2b is increased and T1>T3 decreased correspondingly.

 

Well ok, this is what I have done so far:

Code:

     Tooth  Pitch   Outside
   T1    18    72mm     80mm
   T2    22    88mm     96mm
   T3    27    108mm    116mm

Code:

T1>T3    120mm
T1>T2    80mm
T2>T3    98mm

First I calculated the angles of the left triangle (T1, T2a, T3). With cos-calculation I got the following angles:
Half T1: 54.33dgrs
T2a: 84.13dgrs
Half T3: 41.54dgrs

Second step was to calculate the triangle T1, T2a, T2b. So with de values above I could calculate the length of T2a>T2B. I got a length of 129.98mm.

Third step is to calculate the vertical distance between T1 and T2a/b. You can do this by calculating the triangle T1, T2a and the center (90dgrs angle). The vertical distance is 46.65mm.

Last step is to calculate the vertical distance from the center to T3, this is simply 120mm-46.65mm, so this is 73.35mm.

These last two values can be checked with pythagoras.

So calculating the 'diamond' is not that hard, but it is hard to get the tooth to line up correctly.