6
Operation and Maintenance (cont.)
TUNING BY PLUNGER ADJUSTMENT
1.
With the tray mounted, loosen or remove the
hex nut at the back of the unit.
2.
Insert a screw driver into the slot of the plunger
(see Figure 3) and turn it clockwise until the
plunger hits the armature.
3.
Back out the plunger by turning it counter-
clockwise three full turns.
4.
Replace and tighten the hex nut.
5.
Check the deflection. See “How to Measure
Displacement”.
Eriez HS-5 units operate with a maximum tray stroke
between .110" and .120" (2.8 mm and 3.0 mm). If
the deflection sticker reading is more or less than
this, further tuning can be done by turning the
adjustable plunger. To decrease deflection, turn the
plunger counter-clockwise; to increase deflection turn
the plunger clockwise. If this air gap adjustment does
not produce the desired performance, further tuning
by replacing springs is necessary.
TUNING BY REPLACING SPRINGS
To obtain the maximum desirable deflection, it
may be necessary to add, subtract or substitute
tuning spring leaves in the tuning spring stack
(see Figure 4) at the front of the unit.
The following general rules, which apply only to
the Feeder operating ideally on the “normal” side
of its “tuning curve,” should be borne in mind
FIGURE 3
FIGURE 4
when making tuning adjustments to increase or
decrease the displacement:
1.
To DECREASE the tray displacement,
DECREASE the stiffness of the tuning springs.
2.
To INCREASE the tray displacement,
INCREASE the stiffness of the tuning springs.
If decreasing or increasing the tuning spring
stiffness has an opposite effect, it means that the
spring stiffness is great enough that the unit is
operating on the “opposite” side of its tuning
curve. The spring stiffness should be reduced
until the behavior is in accordance with rules 1
and 2. The unit can then be properly tuned to
the desired displacement.
As a guide to the stiffness of individual tuning
springs, each spring is marked with a code num-
ber- example, 5-27. The first number (5) is the num-
ber of fiberglass plies in the spring. The following
number (27) indicates the relative stiffness of the
spring; the higher this number the stiffer the spring.
The total stiffness of the tuning spring stack is the
sum of the relative stiffness numbers. By various
combinations of different ply springs having differ-
ent relative stiffnesses, practically any desired to-
tal stiffness can be obtained.
When tuning is completed, make sure the adjust-
able plunger lock nut is tightened down.