Humboldt H-4210A Portable, Static Cone Penetrometer - Manual (Page 4)

Maintenance
Your Cone Penetrometer is a ruggedly-designed device intended to tolerate a reasonable
amount of field abuse.
The most critical requirement is keeping foreign matter outside the annulus between the
Inner and Outer Rods. It is recommended that a drop or two of lightweight machine oil
be applied frequently to the annulus. (A schedule of every 2-3 days is recommended if
the unit is being used daily). The Inner Rod is a surface-ground stainless steel rod which
will not rust. The Outer Rod is made of a high-strength alloy steel tubing which is subject
to ru sting. The machine oil will curb that tendency.
Always make an attempt to apply a normal (vertical or in-line) thrust on the assembly as it
is pushed into the ground. A severe horizontal thrust coupled to a normal, vertical thrust
could produce a situation in which the rods could be bent. It is infinitely easier to avoid
bending the rod than to straighten the rod.
Periodically inspect the Cone Assembly. If the Cone Assembly has suffered excessive
wear, it needs to be replaced. The original diameter of the Cone is 0.544". When the
outer diameter is reduced to a diameter of 0.520", it is recommended that the point be
replaced.
Repair
If you notice that your penetrometer is leaking or will not hold pressure, you will need to
replace the “0 ” ring (Item 5) on the Adjustment Screw (Item 4) and/or the piston (Item 6).
Adjustment Screw“0” Ring Replacement:
1. Remove the Outer Rod Assembly (Item 8 or 11) from the Head Assembly (Item 1).
2. Clamp the Head Assembly in a vise with the brass Adjustment Screw pointing up.
3. Remove the Adjusting Screw from the Head Assembly and discard the “0” ring.
4. Install the new “0” ring, being careful not to damage it.
5. Fill the reservoir with automatic transmission oil until flush with the top.
6. Drop in the Adjustment Screw and thread clockwise until flush with the top. (Note:
Oil will run out during this step preventing air from being trapped inside).
7. Screw the Outer Rod Assembly into the Head Assembly.
8. Continue to screw the brass Adjustment Screw clockwise until the needle on the
gauge begins to move. At this time, back off the screw until the gauge reads zero.
9. The Static Cone Penetrometer is now ready for use.
Piston “0” Ring Replacement:
1. Remove the Inner/Outer Rod Assembly (Item 8 or 11) from the Head Assembly
(Item 1).
2. Remove the Insert (Item 7) from the Head Assembly. (Note: For this procedure, you
will need a 3/8"- 16 x 2" long bolt and nut. Screw the bolt and nut into the insert
and use the nut to jam the bolt; this will prevent the bolt from backing out of the
Insert. Now, use the bolt to screw the Insert out of the Head. This procedure can be
made easier if the Head Assembly is slightly heated at the Insert. (Leaving the nut
and bolt in the Insert will facilitate reassembly).
3. Remove the Adjustment Screw (Item 4) and drain the oil from the unit.