A maximum relief valve setting of 40 psi must be maintained.
Higher pressure may overload the motor or cause damage to the
hoses. At least a 30 psi relief valve setting must be maintained
to assure an adequate coolant supply to equipment.
The water circulating tank should recleaned periodical lyandreplenished with fresh water and lubricant. Oilthe motor shaft
bearings several times a year with a good grade of light motor oil. The pump bearings require no lubrication other than that
provided by the coolant.
Unplug motor from power before making any motor repairs or
4.2 CARBON BEARING REPLACEMENT
It is generally advisable not to replace carbon bearings in the field.
This operation requires tools and experience. If done improperly
it can ruin the pump and/or burn out the motor. Usually, when
carbon bearings are worn out, body and cover casting are equally
worn, and replacement of the whole assembly is indicated. How-
ever, if field replacement becomes necessary, the following pro-
cedure is applicable.
To remove old bearing, heat pump body (or cover) to about 300 to 400 degrees F. Since thermal expansion rate of metal is
much higher than that of carbon, carbon bearings will drop out readily.
Do not heat casting over 400 degrees F to prevent warping it.
To install new earing, make up a proper arbor that slips with
at least 0.005-inch clearance into bearing bore, with a shoulder
slightly larger than the outside diameter of bearing (Figure 4.)
Carbon bearings are made several thousandths
oversize to housing bore to assure press fit.
Use a hand press or bench vise (rather than a hammer) for press-
ing bearing in, Make sure face of casting is at right angles to
movement of arbor. Press bearing in flush with casting face,'
machine flush if necessary. Use reamer of finished bore size
501-,502 in/dial) to ream bearing to proper Inside diameter.
There is approximately l/64-inch stock (indiameter) to be re-
Figure 4. Bearing Installation