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1. Maintenance/Replacements

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the oil seals, and the timing gears. All are lubricated and

wear should be minimal if clean oil of the correct grade is

always used. Seals are subject to deterioration as well as

wear, and may require replacement at varying periods.

Sealing rings are designed to operate with no rubbing

contact, once temperature and thermal growth have

stabilized. The rings, which are stationary, do rub the

rotating sleeves briefly during temperature cycles which

result from starting and stopping the blower. However,

the hardened sleeves and the sealing rings are treated

with a dry lubricant coating which provides initiallubrica-

tion during break-in wear.

If the sealing rings become excessively worn, greater

leakage from the vents will occur. Seal rings should be

replaced if vent leakage becomes excessive, or if inspec-

tion at the time of blower disassembly shows more than

.010" (.25 mm) axial clearance between ring and groove.

Shaft bearings have been selected to have optimum

life under average conditions with proper lubrication.

They are critical in the service life of the blower. Gradual

bearing wear may allow a shaft position to change slight-

ly, until rubbing develops between impeller and cylinder

headplate. This will cause spot heating, which can be

detected by feeling these surfaces. Sudden bearing failure

is usually more serious. Since the shaft and impeller is no

longer supported and properly located, extensive general

damage to the blower casing and gears is likely to occur.

Oil seals should be considered expendable items, to be

replaced whenever drainage from the headplate vent cavi-

ty becomes excessive, or when the blower is disassembled

for any reason. Sealing effectiveness can vary con-

siderably from seal to seal, and is also affected to surpris-

ing degree by shaft smoothness and freedom from scrat-

ches under the seal lip. Because of these normal variables,

minor seal leakage should not be considered as indicating

a need for replacement.

Timing gear wear, when correct lubrication is main-

tained, should be negligible over a period of years. Gear

teeth are cut to provide the correct amount of backlash,

and gears correctly mounted on the shafts will accom-

modate a normal amount of tooth wear without permit-

ting contact between lobes of the two impellers.

However, a high oil level will cause churning and ex-

cessive heating indicated by an unusually high

temperature at the bottom of the gear housing. Conse-

quent heating of the gears will result in loss of tooth

clearance or backlash, and rapid wear of the gear teeth

usually will develop. Continuation of this tooth wear will

eventually produce impeller contacts (knocking), and from

this point serious damage will be unavoidable if blower

operation is continued. A similar situation can be produc-

ed suddenly by gear tooth fracture, which is usually

brought on by sustained overloading or momentary shock

loads.

Operating problems may also develop from causes

other than internal parts failure. Operating clearances

within a blower are only a few thousandths of an inch.

This makes it possible for impeller interferences or casing

rubs toresult from shifts in the blower mounting, or from

changes in piping support. Foreign materials sucked into

the blower will also cause trouble, which can only be cured

by disconnecting the piping and thoroughly cleaning the

blower interior.

If this type of trouble is experienced, and the blower

is found to be clean, try removing mounting strains.

Loosen blower mounting bolts and reset the leveling and

drive alignment. Then tighten mounting again, and

make

sure that all piping meets blower connections accurately

and

squar~ly

before reconnecting it.

A wide range of causes for operating troubles are

covered in the TROUBLE SHOOTING CHECKLIST.

The remedies suggested there in some cases

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to be

performed by qualified mechanics with a good

background of general experience, using procedures

detailed in this manual. Major repairs generally are to be

considered beyond the scope of maintenance, and should

be referred to the nearest Distributor listed on the last

page.

Warranty failures should not be repaired at all, unless

specific approval has been obtained through a Sales Office

before starting work. Unauthorized disassembly within

the warranty period may void the warranty.

When a blower is taken out of service it may require

internal protection against rusting or corrosion. The need

for such protection must be a matter of judgment based

on existing conditions as well as length of downtime.

Under favorable conditions, protection will probably not

be needed if shutdown is not longer than a month. Under

atmospheric conditions producing rapid corrosion, the

blower should be protected immediately. See long term

storage suggestions on page 3.

It is recommended that major repairs, if needed, be

performed by a factory authorized distributor listed on

the last page. However, it is recognized that this may not

always be practical especially when a spare blower is not

available. If a blower is out of the warranty period,

mechanical adjustments and parts replacement may be

undertaken locally at the owner's option and risk. It is

recommended that Factory Parts be used to insure fit and

suitability. The maintenance of a small stock of on-hand

spare parts can eliminate possible delays. When ordering

parts give Item Numbers and their work descriptions

from Figures 6 or 7 and Table 6. Also specify quantities

wanted, and the blower size and serial number from the

nameplate.

Repairs or adjustments are best performed by person-

nel with good mechanical experience and the ability to

follow the instructions in this manual. Some operations in-

volve extra care and patience, and a degree of precision

work. This is especially true in timing impellers and in

handling bearings. Experience indicates that a high

percentage of bearing failures is caused by dirt con-

tamination before or during assembly. Therefore, the

work area should be cleaned before starting disassembly,

and new or re-usable parts protected during progress of

the work.

In the following outlines of repair procedures,

numbers shown in brackets ( ) correspond to the Item

Numbers used in assembly drawings, Figure 6 and 7 and

parts list, Table 6. It is recommended that the procedures

be studied carefully and completely, with frequent

reference to the drawing, before starting work. This will