looking to design an automated backlash checker for gearheads

[cliff_turnell]

Hi Group,

I am in the beginning stages of designing an automatic backlash checker for small gearboxes (Nema 17 and Nema 23, possibly as large as 34) and wanted to bounce my ideas off this group. the basic idea is to have a stepper motor w/ encoder mounted to the input of the gearhead, "lock" the gearhead output shaft in place, apply a CW torque of X IN-LBS and record encoder count, apply a CCW torque of X IN-LBS and record encoder count, compare those readings to obtain angular backlash, "unlock" gearhead output shaft, rotate gearhead output shaft 90 degrees ( by virtue of stepper motor and whatever ratio I am testing) and repeat process. I plan on controlling the process via PLC (should be a fairly straightforward program). Where I am getting hung up is finding a way of securing the output shaft. I am trying to find a thru bore brake or some sort of air powered clamping mechanism for a .500" diameter output shaft that I can engage via PLC signal. My first thought was to a have a motor/brake combo coupled to the output shaft but I am not sure if I will be able to back drive the motor coupled to the output shaft. If anyone has any ideas as to how I might accomplish this I would love to hear any/and or all ideas! Thank you for your time and have a great day!

Regards,
Cliff

[jboggs]

I would examine the options available for automatic chucks on lathes. They engage and disengage cylindrical surfaces all day long. Maybe some sort of segmented tapered wedge arrangement like an expanding mandrel or some of the high-end hub locking devices.

[cliff_turnell]

a Pneumatic chuck might fit the bill perfectly, or some sort of electric clutch...