GEH-764AB
Polyphase Switchboard WaHhour Meters
ing the meter register from right to left.
The test constant marked on the nameplate or disk
is for use only in calibrating and checking the meter
and must not be used in connection with the register
reading.
end of'
disk shaf't
Cal
Upper jewel
assembly
Fig.
2.
Open-type ball bearing
MAINTENANCE
Bearings
The lower bearing may be one of two forms as
follows:
a. The oiltight jewel-pivot bearing.
b. The open-type ball bearing.
The oiltight jewel-pivot bearing, Fig. 1, consists of
a jewel assembled within an adjustable bushing at the
bottom of the meter frame, and a pivot which is
screwed into the lower end of the disk shaft.
The open-type ball bearing consists of a ball held
between an upper and lower jewel and protected with
a sleeve as shown in Fig. 2.
The upper bearing consists of a guide pin mounted
in an adjustable top-bearing plug and a guide bushing
set into the tip of the disk shaft.
1.
Lubrication of Oiltight Jewel-pivot Bearing
All jewels shipped from the factory in meters are
properly lubricated. Since meters may be stored for
indefinite periods before use and since the length of
time between tests is increasing, it is recommended
that all jewels be examined for proper oil level before
the meter is placed in service and that General Electric
6
Watthour Meter Jewel Oil be added, if required, to
raise it to the level indicated in Fig. 1. It is not al
ways necessary to disassemble the jewel screw for a
second oiling, as there is little chance for the oil in the
reservoir to be lost.
Jewels shipped separately as supplies are not oiled
at the factory and must therefore be oiled before they
are installed in meters.
The following directions for initial oiling of the Oil
tight Jewel Screw are given with reference to Fig. 1:
a. Remove the guide bushing by means of the
combination jewel-and-pivot wrench.
b. Invert the screw and allow the jewel-setting
plug to drop out. If the plug does not drop
out readily, gently tap the head of the screw.
c. By means of a wire-loop oil applicator, put
two drops of G-E Watthour Meter Jewel Oil
in the reservoir of the jewel screw. Allow a
short time for the oil to run to the bottom of
the reservoir. It is necessary that this reserv
oir under the jewel plug be filled.
d. Drop the jewel plug in the screw.
e. Replace the guide bushing and screw it down
tightly.
f. Put in another drop of oil which will run down
through the oil slot of the guide bushing into
the jewel cup.
g. Inspect the oil level, which should be as shown
in Fig. 1. Because of minor variations in me
chanical dimensions of the reservoir or varia
tion in size of the drops obtained from the
wire loop, three drops of oil cannot always be
taken as the correct amount. If more is need
ed to fill to the right level, it should be added.
The pivots require no lubrication other than that
obtained from properly oiled jewel screws.
The top-bearing assembly should require no atten
tion during the normal life of the meter.
2.
Replacement of Oiltight Jewel-pivot Bearing
At each test period the jewel screw should be re
moved, inspected for oil level, and re-oiled with G-E
Wattthour Meter Jewel Oil if necessary.
If a meter requires a new lower bearing, both the
pivot and jewel should be changed. Pivots are in
jured by operation in badly worn or damaged jewels.
The following procedure is recommended for re
placement of a pivot and jewel:
a. Loosen the top-bearing clamping screw so that
the bearing plug is free to move.
b. Remove the jewel screw from its adjustable
bushing. Do not disturb the setting of this
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