Veris Technologies Quad 1000 Soil EC Mapping System - Operating Instructions - Manual (Page 31)

OM17-Quad1000
6-10
Procedure #4 Spring Plunger adjustment and replacement
The spring plungers are located in the center of each disk electrode hub cap, and are vital to
maintain good continuity through the disk 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 disk hub bearing preload by grasping disk blade and pushing from
side to side. If there is any noticeable movement, bearings are failing --and
this can damage the spring plunger; see procedure #8 for replacement.
2) Remove the locking nut.
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 4.1 below to view proper clearance.
7) Reinstall locking nut and tighten firmly. Do not allow plunger to rotate while
the locking nut is tightened.
8) Re-test disk electrode continuity
Figure 4.1
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.