craig0a
Mechanical
- Apr 8, 2014
- 10
Hello,
I am having some trouble with theory not matching practice in a spur gear train that I designed. The train consists of about 200 1" stainless steel spur gears held in place in a horizontal plane between two plates. They are driven from above by a vertically mounted motor connected via a flexible shaft coupler.
Problem 1: In theory, spur gears don't have any thrust. But when running this system, the motor/mounting system is actually being lifted upwards (over 20lbs.) I am not sure where this thrust force is coming from: small angles in my train being accumulated?
Problem 2: Slowing down and speeding up the system to/from rest is not happening uniformly over the gear train. So what happens is that either the motor is being torqued by the moment of inertia of the gears or the motor isn't putting out enough power to turn the gears at the slowest speed and it is torquing itself; in either case the net result is that my flexible shaft coupler is being very twisted, probably almost to the shear point, and my gear train locks itself (that is, before attaching the motor I can turn it by hand, but after the bad slow down, I can turn it by hand in the opposite direction of rotation, but it is locked against rotation in the direction the motor had been driving it). Is there a safe way to slowly introduce and remove rotational speed to the system so that components aren't being caught between resistance and drive?
I apologize if these are commonly known problems which standard solutions; I am still in training as a mechanical engineer.
Thank you for any suggestions and help!
Best regards,
A. Craig
I am having some trouble with theory not matching practice in a spur gear train that I designed. The train consists of about 200 1" stainless steel spur gears held in place in a horizontal plane between two plates. They are driven from above by a vertically mounted motor connected via a flexible shaft coupler.
Problem 1: In theory, spur gears don't have any thrust. But when running this system, the motor/mounting system is actually being lifted upwards (over 20lbs.) I am not sure where this thrust force is coming from: small angles in my train being accumulated?
Problem 2: Slowing down and speeding up the system to/from rest is not happening uniformly over the gear train. So what happens is that either the motor is being torqued by the moment of inertia of the gears or the motor isn't putting out enough power to turn the gears at the slowest speed and it is torquing itself; in either case the net result is that my flexible shaft coupler is being very twisted, probably almost to the shear point, and my gear train locks itself (that is, before attaching the motor I can turn it by hand, but after the bad slow down, I can turn it by hand in the opposite direction of rotation, but it is locked against rotation in the direction the motor had been driving it). Is there a safe way to slowly introduce and remove rotational speed to the system so that components aren't being caught between resistance and drive?
I apologize if these are commonly known problems which standard solutions; I am still in training as a mechanical engineer.
Thank you for any suggestions and help!
Best regards,
A. Craig