User manual

Barrett Technology, Inc.
BA4-310 System User Manual Version 1.1
66
Figure 35 - Proper Position of Wrist Cables for Pre-Tensioning
The left and right circuits of the input transmission, with their three stages of reduction, require
extra attention during pre-tensioning. The procedure for both the left and right cabling circuit
begins by tightening the worms to 0.23 N-m (32 oz-in) until the cables in the first stage are taut.
Then carefully back-drive the wrist through a full cycle and back again. Listen for cables
scrubbing against each other, and if you feel resistance, investigate. Cables may be running
over each other or stuck in termination slots. They should be evenly spaced on the pulley
surfaces.
The third stage cables must be carefully placed to prevent both scrubbing between cables
placed too close together, pulling at odd angles, or falling into termination slots if cables are too
far apart. Cables placed too far apart so that the winding angle is severe will eventually
reorient themselves, and they may not go where you want them.
Once the wrist has been rotated through a full cycle and returned to its starting position, be sure
that none of the cables run over the splits in the pulleys and pinions. Once the cables have been
repositioned as shown in Figure 35, re-tension to 0.23 N-m (32 oz-in) by turning the worm.
Repeat the process of running the wrist through its range of motion and re-tensioning until all
the cables are tight.