HARRISTON INDUSTRIES 4240 CLOD HOPPER, Operator'S Manual, Page: 66 / 84

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5.2.2 BREATHER CLEANING
Each gearbox is equipped with drain, level and fill
plug. Some fill plugs are equipped with a breather
that vents the internal pressure to atmosphere. As the
gearbox temperature increases and decreases dur-
ing the operating and stopped modes, the pressure
in the gearbox will increase or decrease if it is not
vented to atmosphere. An increase in internal pres-
sure will cause the shaft seals to leak until the gear-
box runs low on or out of oil. To check on or clean the
breather, follow this procedure:
1. Place all controls in their OFF or neutral position.
2. Turn the power OFF at the master panel and lock-
out tag-out.
3. All Nord gearboxes are designed with metric sock-
et-head cap screws as drain plugs in the lowest
part of the gearbox for ease of draining. The level
fill plug is a hex head cap screw. Both types of
plugs are equipped with gaskets to prevent oil
leaks when tightened.
4. Remove the fill plug / Autovent breather from the
gearbox.
5. The Autovent plug is brass in color and will be lo-
cated at the highest point on the gearbox. It op-
erates like a check-valve to allow the reducer to
relieve internal pressure while preventing lubricant
contamination during cooling. A spring presses
a ball or plunger against a machined orifice un-
til pressure exceeds 2 psi. Above 2 psi the air is
allowed to escape depressurizing the gearbox.
When internal pressure drops below 2 psi, the
Autovent re-seals thus closing the gearbox to the
outside environment. After shutdown, the reducer
cools along with the air inside the gearbox. The
unit will temporarily maintain a slight vacuum until
normalization occurs.
6. Check that the vent passage through the plug is
open.
7. If plugged, soak in a solvent over night.
8. Use a high-pressure air hose to blow the passage
open. Use a probe to clear the passage if the hole
is caked with dirt.
9. Install and tighten the breather plug.
FIG. 44 AUTOVENT BREATHER (TYPICAL)
Straight
Offset
Schematic
IMPORTANT
Always clean the breather if any leaks
are noticed around shafts.