Owner`s manual

9
MAINTENANCE
BALL NUT INSPECTION
Disassembly of the ball nut must be completed to
permit inspection (refer to ball nut disassembly on
page 7). A Ball Bearing Replacement Kit containing
bearing balls and ball guide is available from Mar-
ket Forge parts distributors. Should the ball nut show
excessive wear I the entire Saginaw Screw assem-
bly must be replaced. Inspect components for wear
points:
Balls. Check a random sample of 20 balls for
signs of scufng or sh scaling. Diameter varia-
tion between balls and true roundness of each
one must be within .0001 inch. Balls which fail to
meet these requirements should be replaced us-
ing the Ball Bearing Replacement Kit.
Guide. Inspect the pick-up ngers which consist
of short extensions at the end of each half guide.
Minor burrs can be removed and the guide re-
used. If a ball impression appears on the nger
tips or the halves were distorted during removal,
the guide must be replaced.
Ball Nut. Inspect the internal threads of the ball nut
for signs of excessive wear, pitting, gouges, cor-
rosion or spalling in the ball groove area. If these
aws are detected, the entire saginaw screw as-
sembly should be replaced.
BALL NUT REASSEMBLy AND BEARING RE-
PLACEMENT
With the ball nut disassembled (refer to ball nut dis-
assembly on page 7) complete the following reas-
sembly, using either existing bearing balls or substi-
tuting a Ball Bearing Replacement Kit (part number
91-1490).
Clean all ball nut components with a commercial
solvent and dry thoroughly before reassembly.
Slide the ball nut onto the free end of the screw, round
nut end rst, as shown in Figure 5 on page 12.
Replace the stop collar (5) , Figure 5 on page 12.
CAUTION:
BEARING BALLS ARE RETAINED IN ThE BALL
NUT ONLy WhEN IT IS MOUNTED ON ThE
SCREW. TO PREVENT ThE NUT FROM AC-
CIDENTALLy SPINNING OFF ThE SCREW ThE
STOP COLLAR (OR OThER OBSTRUCTION)
MUST BE PLACED ON ThE FREE END.
Center the ball nut grooves on the shaft grooves
by inserting a cylindrical object (a drill bit shank,
or other object of same diameter as bearing
balls), into the ball nut return circuit hole. Care-
fully withdraw, taking care not to disturb nut-to-
a.
b.
c.
1.
2.
3.
4.
screw alignment.
Insert bearing balls into the guide opening using
slight rotation of the screw to help feed them into
the grooves. Place remaining balls into one half of
the return guide.
NOTE: If a Ball Replacement Kit is to be installed,
rst count out the same number of new bearing balls
as the number of worn balls being replaced. DO NOT
try to add extra balls. There must be some free space
in the circuit so that balls will roll and not skid.
Place a dab of bearing grease at each end of the
half return guide to hold balls in place. Place the
mating half return guide over the half lled with
balls and insert the two ends of the ball guide into
the holes in the ball nut. Seat by tapping gently
with a rawhide or plastic mallet.
Inspect for free movement of the ball nut along
the entire stroke. There should be no binding,
squeal, or roughness at any point.
Place guide clamp in position and secure with
clamp screws.
C
RANK SLEEVE REPLACEMENT
The driving end of the Saginaw Screw (2) is formed
into a slotted sleeve which receives the engage-
ment pins of the removable hand crank (1 ). A worn
or chipped sleeve which causes the hand crank to
slip out of engagement during kettle tilting can be
repaired with a Crank Sleeve Replacement Kit (part
number 91-2155).
The Saginaw Screw assembly must be removed
from the kettle to complete kit installation, (see sagi-
naw screw assembly removal on page 7). The col-
lar (next to the ratchet wheel, Fig. 5 on page 12) is
removed by driving out the roll pin which secures it
to the screw shaft. The replacement sleeve is slid
over the faulty shaft end and fastened with a roll pin.
The repair is completed by re-mounting the Saginaw
Screw assembly.
BRAKE MEChANISM DISASSEMBLy & REPAIR
The brake mechanism, shown exploded in Figure 4-
8, functions as an anti-coast device for the Saginaw
Screw. When the hand crank (1) is turned clockwise
(kettle raising) , a ratchet wheel turns freely inside the
ratchet stop. Any “free wheeling” counter clockwise
screw motion is prevented by engagement of ratchet
wheel teeth in the stop and the drag of friction be-
tween the shaft collar, and the ratchet wheel face. Ad-
ditional torque applied by the hand crank, as in kettle
5.
6.
7.
8.