TM 9-4910-638-14&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 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, there is 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 bearing, four large clamping screws and four smaller locking
screws.
The adjustment is made by setting each set of screws separately beginning with the center adjusting screws and
then the upper and lower screws.
First loosen all four setscrews. Tighten the center clamping screws while moving the handwheel back and forth
until a drag is felt on the handwheel. Tighten the lockscrews of this set until it leaves a slight drag on the handwheel
as the sleeve is moved down. Should this adjustment leave no drag or too great a drag after tightening the
lockscrews, loosen the lockscrews 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 THE MOST IMPORTANT AND SHOULD BE MADE PROPERLY.
Adjust the top and bottom screws in the same manner. The drag on the handwheel should be increased after
locking each of these screws to insure that there is a good bearing on the top and bottom bearing areas of the
sleeve. There should be a very definite drag on the handwheel as the sleeve is 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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