Parr Instrument A1120HC10 - Manual (Page 3)

A1120HC10 Magnetic Drive
w w w . p a r r i n s t . c o m 3
The O-Ring Seal
The 1137HCHA O-ring, which seals the top plug in
Parr magnetic drives, is made of PTFE. O-rings of
alternate materials are available to meet specifi c re-
search applications if required. PTFE O-rings should
be replaced each time the drive is re-assembled.
Servicing the Outer Drive
The outer drive is supported by two high quality
sealed ball bearings which do not require lubrica-
tion. Any oil leak or noise from the bearing will
indicate that the seal or the bearing has failed and
the bearing must be replaced.
To disassemble the outer drive:
1. Remove the four socket head screws located
near the top of the outer housing; then lift the
cover from the housing to expose the upper
snap ring. Peel the snap ring out of its groove
with a small screwdriver; slide it upward and
remove it.
2. Take a fi rm grip on the outer drive housing and
pull it upward to separate the outer assembly
from the magnetic drive housing. The lower
bearing may not come out with the housing. If
not, remove at this time.
To reassemble the outer drive:
1. Slide the lower spiral snap ring back into its
groove; then slide the lower ball bearing onto
the inner hous ing. The inner magnets should
hold the bearing at the middle of the housing.
2. Slide the outer drive assembly over the rotor,
thereby pushing the lower bearing down against
the lower spiral snap ring. Hold both parts fi rmly
during this step so that the magnets do not slam
the outer drive into place.
3. Insert the upper wave spring into its groove in
the outer drive housing and slide the ball bear-
ing into place against the wave spring, then an-
chor the bearing by pushing the retaining snap
ring downward until it snaps into its groove
above the bearing. During this step suffi cient
pressure must be applied against the snap ring
to force the wave spring downward and allow
the snap ring to drop into its groove. This can be
done with a pair of screw drivers, using alternat-
ing pressure on the snap ring. This must be done
carefully to be sure that the screw drivers do
not slip and damage the seals in the bearings.
To simplify the opera tion, Parr offers a magnetic
drive assem bly tool (Part No. 2086HC) consist-
ing of a properly sized cup which can be pushed
downward against the snap ring to force it into
its groove.
4. Replace the top cover and secure it with the four
socket head screws.
Cooling Sleeve
The A2685HC cooling sleeve mounted on the
1135HC4 magnetic drive body includes two 827HC
O-rings which seal against the body. After extended
operation these O-rings will require replacement.
To replace the O-rings, remove the magnetic stir-
rer from the vessel head as described previously.
Remove the 825HC retaining ring from the 1135HC4
body and slide the cooling sleeve off. Remove the
O-rings from the inside of the cooling sleeve. Care
must be taken not to scratch the O-ring grooves.
Clean any accumulated lime deposits from the
inside of the sleeve. To reinstall the cooling sleeve,
insert new O-rings into the grooves, moisten the
O-rings with water, slide the sleeve back onto the
housing, and reinstall the 825HC retaining ring.