TM 9-4910-579-14&P
ADJUSTING THE BORING SLEEVE MAIN BEARING
An improper adjustment of the main sleeve bearing on the Cylinder Boring Machine may cause trouble in the
operation of the machine. This adjustment should be checked frequently. The adjusting of the sleeve bearing is a
delicate operation and too much stress cannot be laid upon it. The most important thing to keep in mind in making
this adjustment is that in order to maintain the maximum bearing area on the sleeve, you must have a good fit on
the adjustable bearing at the extreme top and extreme bottom of the bearing area. If you have a good adjustment
on the two center screws of the split bearing and the top and bottom screws are not clamping the bearing down
against the sleeve, the sleeve will not be properly stabilized in the bearing and chatter, size variation and out-of-
round trouble will develop in the bore.
The Cylinder Boring Machine sleeve bearings are properly adjusted when they leave the factory, but due to
vibration and handling in shipment, you have no assurance that the sleeve will be properly adjusted when the
machine is uncrated. Due to the importance of this adjustment, the machine should be readjusted before being put
in service.
Four sets of adjusting screws are provided for this beating, four large clamping screws and four smaller locking
screws.
The adjustment is made by setting each set of screws separately beginning with the upper and lower adjusting
screws and then the two center screws.
First loosen all four setscrews. Tighten the bottom clamping screw while moving the handwheel back and forth until
a considerable drag is felt on the handwheel. Tighten the lockscrew of this set until it leaves a slight drag on the
handwheel as the sleeve is moved up and down. Should this adjustment leave no drag or too great a drag after
tightening the lockscrew, loosen the lockscrew and reset the clamp screw. Over tightening of the lockscrews will
distort the bearing and cause uneven wear.
THE ADJUSTMENT AT THE BOTTOM OF THE BEARING AND THE ADJUSTMENT AT THE TOP OF THE
BEARING IS MOST IMPORTANT AND SHOULD BE MADE PROPERLY BEFORE PROCEEDING WITH THE
CENTER ADJUSTMENT SCREWS.
Adjust the top set of screws in the same manner. The drag on the handwheel should be slightly increased after
locking these screws. Now that both the top and the bottom sets of screws have been adjusted, the center sets of
screws should be adjusted in a similar manner and after all adjustments have been made, there should be a very
definite drag on the handwheel as the sleeve is raised or lowered manually by cranking.
It is extremely important that the sleeve bearing adjustment be properly made when the bar is new and it is
necessary that you have this additional amount of drag on the sleeve during the break-in period. If this adjustment
is carefully made, and maintained during the first few months of operation, it will be possible to then maintain hole
size, eliminate chatter and out-of-roundness for long periods of time without sleeve adjustment.
PROTECT THE BASE OF THE MACHINE Upon its accuracy depends the accuracy of the boring operation. Do not
set the machine on a rough or hard surface. Always set the machine on a soft piece of wood or cardboard.
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