Machine Design‎ > ‎Examples‎ > ‎

Gear Challange

Hands–On Gear Homework

Solve the problem below before lab using the Gear Exercise Worksheet on the other side of this page. In lab, your team will test your result on the Wall of Moments in the hallway outside the Design Studio. If the weight tests for both the moment exercise and this gear exercise are successful and this FBD write-up is correct, the team will receive an extra high power component to add to their robot kit!

Step 1: Review the Gear-Pulley Mechanism. The rigidly connected gear and pulley combination on the left is subassembly 1, and the combination on the right is subassembly 2.

The known parameters are:

 Radius of pulley 1 p1 = 2cm 
 Radius of pulley 2  p2 = 3cm
 Pitch radius of gear 1 r1 = 2.5cm 
 Pitch radius of gear 2  r2  = 5cm
 Mass of subassembly 1s1 = 40g
 Mass of subassembly 2 s2 ­­= 84g 
 Mass hanging from subassembly 1 m1 = 60g 

The challenge is to find the values of mass m2 that will initiate motion

.2. Draw the FBDs of both subassemblies 1 and 2 below.  

FBD of Subassembly 1

FBD of Subassembly 2

3. Write out the equilibrium equations for each subassembly below.

Subassembly 1

Subassembly 2

4. Determine the equation for mass m2 that would keep the system in equilibrium.