7
TUNING FOR NON-STANDARD TRAYS
(Note: See “Special Trays and Attachments”)
If it is necessary to tune the unit to an off-size or
non-standard tray, follow this procedure:
1.
Attach the tray, making sure that all lockwashers
are in place and the fasteners tight.
2.
Energize the unit at the nameplate voltage
and frequency.
3.
(a) During tuning if a hammering or striking
noise occurs when the unit is turned off and
on quickly, the displacement is well in excess
of normal. Whether striking or not, if the
displacement exceeds the normal range for
that particular size of tray (see Tuning Guide-
General Information), it must be reduced by
substituting a tuning spring leaf or leaves of
displacement and feed rate.
(b) During tuning if the displacement at full
voltage is below the nominal range for that
particular size tray, and greater displacement
is desired, increase the tuning spring stiffness
by substituting leaves of greater stiffness or
by adding more leaves.
TUNING FOR DIFFERENT
CONDITIONS OF TRAY LOADING
Units with Eriez-built trays are factory tuned for
normal displacement (approximately .110" to .120"
[2.8 to 3.0 mm]) with light loading (light head load,
light materials, limited depth of flow of heavier
materials). Ordinarily this tuning will not need to
be changed. In no case, however, should the unit
be permitted to deflect more than .120" (3.0 mm)
without load.
CAUTION: A small amount of striking during
tuning is permissible, but must not be allowed
during regular operation since damage to the
feeder can result.
Operation and Maintenance (cont.)
Repairs
SPRING CHANGE OR REPLACEMENT
Although the non-metallic springs used in the Feeder
have outstanding life characteristics, failure may
eventually occur, especially if the displacement is greater
than normal. The symptoms of such failure will be:
1.
Erratic behavior of the unit, or
2.
Greatly reduced displacement.
If spring failure is suspected, the tuning spring stack
should be removed by removing the six bolts attaching
it to the body and the tie bar (see Figure 4).
Carefully examine each tuning spring for signs of
delamination or breakage, especially in the area next
to the spring shims. A failed spring can be recognized
by the appearance of the spring surface. If this surface
is discolored or has a patchy whitish appearance,
perhaps accompanied by surface burying or other
irregularity, the spring is defective and should be
replaced with a new spring ordered from the parts list.
NOTE: After any spring change or replacement, it
is very important that the moving plunger be
checked for alignment in the bore of the body
casting. To do this, remove the coil through the
rear of the unit. Now inspect the position of the
plunger. If the plunger is off center in the bore
hole, first loosen the six spring bolts again, then
insert a screwdriver in the narrow gap and pry the
plunger until it becomes centered. Leave the
screwdriver in place and tighten the six spring
bolts. The plunger is now correctly centered and
unit can be reassembled