Chapter 4  Angular Measurements
Angular Position Measurements
Measurements Reference Guide 4-45
Creating the control link
The main goal of the procedures below is to connect the angular position 
measurement fixture to the machine’s spindle or other lifting mechanism 
while ensuring there is no outside force on the clutch control shaft in any 
direction. The fixturing aids listed in Figure 4-17A/B/C/D are provided to 
help you do this.
In long linkages, the Agilent posts may be too flexible, so custom fixturing 
may be needed.
Taking care of the measurement fixture’s clutch
See Figure 4-25.
The angular position measurements fixture’s friction clutch prevents 
unwanted movement of the precision index table’s top when it is 
disengaged from the table’s base. 
NOTE The clutch must never carry any of the weight of the linkage after final 
assembly and tightening of the linkage.
To prolong clutch life, do not rotate the clutch control shaft with respect to 
the rest of the fixture when the clutch is engaged. The clutch is normally 
engaged. To disengage it, rock the control shaft or press it toward the 
fixture’s base.
If the clutch has not been used for more than about two days, it may be 
difficult to disengage it. Before using the clutch, you should manually 
disengage it. In this case, you can rock the clutch by manually tilting the 
clutch control shaft with respect to the rest of the angular measurement 
fixture.
To keep the clutch from being rocked or disengaged during installation, 
whether due to the weight of the linkage assembly or due to tightening, 
hand-tighten the clutch breakaway nut onto the clutch shaft.