Not that I am planning to abuse the lathe by slamming from forward to reverse, I just want to compare my current pulley backlash with others in the same category and take some action if it is too much. I don't want to open up the "Backgear" box unless it is necessary.
DC critter, not 3-Phase.
Unless the controls are FUBAR, one 'cannot' actually "slam it" from FWD to REV (or the opposite).
Anti-plugging relay wants the RPM to have dropped to 400 RPM or so ('base' at the motor is 690 RPM, so about 60%) before a relatively 'hard' STOP, then REV is permitted.
Not so much 'idiot proofing' as 'tired, distracted, or PANICED proofing'.
Gearboxes DO wear and CAN sustain damage, but stresses below 400 RPM must be 'within bounds', as the gearbox was also used on 5 HP and 7.5 HP DC models. Many have also lived long enough to be mated to 5 HP and 7.5 HP AC 3-P + VFD motors.
In VFD (or Solid-State DC Drives..) the 'tronics provide a similar function with a delayed ramp down (or comparable relay in the Beel/BICL).
As to 'necessary'? Far better to open the box NOW,see what is worn, broken, on-the-verge-of, get it repaired, cleaned, and refilled with the proper clean lube than to risk failure in the midst of a priority project with a tight deadline.
Bill
Of course Monarch's specs were a bit tighter than OMC's allowing only a few degrees of slop.