Step 14.3: Compound Gear-Trains

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Step 14.3: Compound Gear-Trains

Compound Gear-Trains

Schematic of Compound, three stage, Gear Train.

Schematic of Compound, Three-Stage, Gear Train

A Compound Gear Train has a minimum of:

•two Gear-Pairs

•two gears on one or more shaft

The image to the left is a Compound Gear Train. There are three Gear-Pairs. There are four shafts in total. Two of the shafts have two gears.

See Also: Simple Gear-Pair, Simple Gear-Trains, Planetary Gear-Trains

 

Compound Gear Train – Gear-Pair 1

GST-14-TRAIN-001

We can use the model from in the previous  - Step Add a Gear-Pair with Fixed-centers

Edit the number-of-teeth as follows.

Here, the number-of-teeth are:

Z1=20Red-14-2, Z2=40Red-14-3.  

The Gear Ratio is Z1/Z2 = 2

Gear-Part 2: Prepare

GST-14-TRAIN-002

Line 1 / Part 1 : LineRed-14-5 in PartRed-14-4 is available from Gear-Pair 1

Line 2 / Part 2 : The Line that joins the gear-centers

1.Edit the Base-Part

2.Geometry toolbar > Add LineRed-14-1b AND Add DimensionRed-14-2 (the actual length is not important).

IMPORTANT rule: You must MERGE PointRed-14-3 and PointRed-14-4

3.Hover + Drag to add LineRed-14-1b from PointRed-14-3  

OR

3.Geometry toolbar > Merge-Points : Click PointRed-14-3 and then click PointRed-14-4

4.Click the graphic-area to complete Merge-Points.

5.Close the Part-Editor.

GST-14-TRAIN-003

GST-14-TRAIN-004

Line 3 / Part 3 :

It is a new Part - it will be the Driven-Gear.

1.Kinematics-toolbar > Add Part: Drag to the PartRed-14-6

2.Kinematics-toolbar > Add Pin-Joint : Click the start-Point of CAD-Line in PartRed-14-6

Click the end-Point of LineRed-14-1b

The length the CAD-LineRed-14-7 along PartRed-14-6 is not important.

Add Gear-Pair 2

GST-14-TRAIN-005

Add Gear-Pair 2

1.Click Machine-elements toolbar > Add Gear-Pair  

2.Click the elements, Red-14-5Red-14-7Red-14-1bRed-14-2 from top to bottom - refer to Preparation images, above

3.Click OK-tiny-11-15  at the bottom of the Command-Manager.

 

GST-14-TRAIN-006

You can see the Gear-Pair 2Red-14-2

 

There are two new gears.

This is a Compound Gear-Train.

You can do the same actions to add more Gear-Pairs.

This last image is a Compound Gear-Train with three Gear-Pairs.

How to add MD-Solid to gears:

1.Use the ALT+H to move the model to the home position - this is important.

2.Click Solids Toolbar > Add Polyline

3.Click a Gear in one of the Gear-Pairs

4.Do 2 and 3 for each Gear-Pair

5.Click Solids toolbar > Add Profile

6.Click each Gear with a Polyline

7.Do 5 and 6 for each Gear

8.Shift+Click each Profile to show the Profile and Extrusion in the Selection-Window.

9.Edit each Extrusion, to offset it etc, to give a model similar to the image to the left.

10.Edit the Parts to add shafts etc.

GST-CompoundGB