Assume a multistage gear reducer (used in forklifts or bed lifts) like the one presented in the following image. Assume that the motor is connected to shaft 1 and the load on shaft 3.
Which gear pair has the highest stress?
- Is it the slowest moving gear towards the lifting end, or
- is the stress equal throughout the mechanism? An internet search has been fruitless.
My intuition is #1. Since the mechanism converts velocity to torque, it has high velocity and low torque on the motor side, but low velocity and high torque on the lifting side. So while the strength of individual gear teeth is the same throughout the mechanism, they're subjected to higher forces on the lifting side, and this is where they'll break first.
I'm been presented with the counter argument that it's simply an energy converter, and the same amount of total energy is present throughout the mechanism. So the stress is the same on the motor side as it is on the lifting side. This feels counterintuitive, but I'm unable to refute it.
TO CLARIFY: The question is about multiple gears in succession, e.g. a series of 5 gears, and whether the output stage is under more stress than the input stage, or whether all teeth experience the same stress throughout. I do readily accept that a simple two gear reducer would have the same stress between the teeth of each gear.
Example would be like this, with motor input on the right and load output on the right, and whether the stress is higher on the output stage teeth (left).