Posted by David Kelly.
Student on team #234, Cyber Blue, from Perry Meridiam H. S. and Rolls-Royce/ NASA Langley.
Posted on 2/14/2000 7:06 PM MST
This is a qustion for Joe Johnson. I am wondering what the ‘no-back’ rollers in the drill motors are. Can you discribe what they are and what they look like? We are having trouble locating them.
David Kelly
Team 234
Posted by Joe Johnson. [PICTURE: SAME | NEW | HELP]
Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.
Posted on 2/14/2000 8:15 PM MST
In Reply to: ? for Joe Johnson posted by David Kelly on 2/14/2000 7:06 PM MST:
David,
The ‘no-back’ pins are deep in the bowels of the transmissions.
To get to them you have to remove everything but the output shaft (from the inside, this shaft looks like a bow tie).
The output shaft as I said looks like a bow tie from the inside. the round section of the bow tie has flats on it. When the carrier drives the output shaft, these rollers are kept in the middle of the flats by the drive pins on the carrier (these pins also drive transfer torque to the output shaft by pushing on the wings of the bow ties).
As long as the rollers are kept in the middle of the flats, they do not jam up against the ring that is fixed to the housing. BUT if the output shaft tries to drive the carrier, the rollers get to the edge of the flats and bind the shaft to the housing.
Thus, the carrier can drive the output shaft but the output shaft cannot drive the carrier. This is a very useful thing for hand tightening and loosening drill chucks, but a lousy thing for rolling robots around.
To disable this feature, all you have to do is remove the pins. They are steel cylinders approx. 3 mm in diameter and maybe 5 mm in length.
I hope this helps.
Joe J.