Veris Technologies OpticMapper - Operating Instructions - Manual (Page 44)

Pub.# OM17-OpticMapper
6-10
Procedure #4 Spring Plunger adjustment and replacement
The spring plungers are located in the center of each coulter electrode hub cap, and are vital to
maintain good continuity through the coulter hub bearings. They are factory preset, and should
not need routine adjustment. If a continuity test shows abnormally high resistance, the plungers
should be checked. This may be performed in the following manner:
1) Check coulter hub bearing preload by grasping coulter blade and pushing
from side to side. If there is any noticeable movement, bearing preload is
incorrect, or bearings are failing --and this can damage the spring plunger ;
see procedure #8 for adjustment or replacement.
2) Remove the 3/8” allen head set screw.
3) Remove the plunger by turning counter-clockwise.
4) Depress the spring loaded tip on a hard surface to determine if
plunger has adequate tension and can move freely.
5) If the plunger will not move freely, replace. Coat the threads with di-electric
silicone grease before installation.
6) If the plunger appears to be in good working order, reinstall in the hub, and
adjust until it bottoms against the spindle end. Rotate 1/2 turn backward to
allow adequate clearance. Improper adjustment will result in premature
failure (too little tolerance) or poor continuity (too much tolerance). See
Figure 3.12 below to view proper clearance.
7) Reinstall locking set screw and tighten firmly on top of plunger. The top of
the setscrew should be even with the face of the hub. If not, remove and
adjust the plunger inward or outward as necessary.
8) Re-test coulter electrode continuity
Figure 3.12
In some cases, you may have to remove the hub cap to service the spring plunger, if the
plunger is rusted in the cap, or if the readings are still unsatisfactory with the new plunger
installed.