The saying goes: “There are many ways to skin a cat”. However, this sounds a bit cruel, so lets change the saying to: “There are many ways to represent gears in Adams View”. This article will show you just a couple of ways to model gears in Adams View, from using to couplings for a purely mathematical representation to using full three-dimensional models for the gears using Adams Machinery.
The model that will be used for the demonstration will be the original cordless drill. It is a simple design that will never run out of battery power, but more importantly, this design has a simple gearbox consisting of a spur gear pair and a bevel gear pair.
Couplers - Joint
The first method that will be shown is probably the simplest and easiest to set up, the joint coupler. With this representation you will not be modelling the gears, but rather the ratio between the motion of two revolute joints.
The first step is to model the drill in Adams View. This was done using revolute joints for the three shafts and adding a motion to the revolute joint attached to the crank or input shaft. The image below shows the wireframe Adams model (note that the gears were not added for this example).
The next step would be to connect the relevant gear pairs. First lets connect the input revolute joint to the center revolute joint. This connection will represent our spur gear connection. Go to the Connectors tab and in the Couplers section select the bottom icon, named “Joint (Add-on Constraint): Coupler”.
Once you click on this icon it will appear as if nothing happened. That is because this tool does not open an additional window, you will need to keep an eye on the bottom left hand side of your screen for directions.
The first step that is asked for is to select the driver joint, so we will select the Input Revolute Joint. The second step is to select the coupled joint, we click on the Center Revolute Joint. As soon as you’ve selected you second joint the coupler icon will appear. The coupler icon is shown in the figure below.
In order to assign the correct gear ratio between the two revolute joints, double click on the coupler icon in order to open up the modify window shown below. You’ve got various options in this window. The first is whether you want to create a two joint or a three joint coupler, for now we are going to stick to a two joint coupler. The second is whether you want to define the ratio between the joints with a scale, a displacement or by a user defined function. For this example, since we are working with gears, it would be the easiest to work with scales. For the scales we can use the number of teeth on the gears, so for the first joint (input revolute joint) we set the scale to 38 and for the second joint (center revolute joint) we can set it to -14. Note that you need to set one of the scales to a negative value to account for the change of rotation direction.
The same process can be followed for the bevel gear set, where you create a new coupler between the center revolute joint and the output revolute joint and define their respective scales as 35 and -16, as shown in the image below.
When you review the results you will see that the center shaft rotates in an opposite direction to the input shaft and at a faster speed corresponding to the 38/14 gear ratio that was input and the output shaft rotates in the correct direction at a speed of 5.9375 times the input speed (38/14 x 35/16).
Next time we will automate the drill by adding a motor from the Adams Machinery Simulation Suite.