“Adjusting Cylinder Carriage Bearings Vandercook SP-15, SP-20, SP-25, Universal Models”
by Gerald Lange
Press bearings need to be oiled on a daily basis. Wipe the bearers’ top and bottom, with a freshly oiled rag, each time you set up the press. Clean the bearers at the front of the press and then move the cylinder to clean the bearers at the rear of the press. If particles of metal show up on the rag after wiping, your bearers have begun to erode. This is not necessarily a reason for adjusting the bearings, but it does indicate that your bearers are worn and disintegrating and that the bearings may need adjustment to compensate. A more important consideration is impression balance, or the relationship of the cylinder to the bed, from side-to-side, from end-to-end. Unless you are mechanically inclined, however, and know what you are doing, cylinder carriage bearing adjustments are best left to a press mechanic (it is highly recommended that this be done on a periodic basis). An even impression across the form is determined by printing a heavyweight proof sheet without inking. Examine the sheet in cross light to detect any variance in impression from one edge to another. Do not overly tighten the lock-up before this test as it could force the form to rise and give a false reading. If impression is off from one side of the bed to another, the most likely problem is that the cylinder carriage bearings or bearers are off balance or worn and will need to be adjusted. [Note: bearings themselves can be replaced. NA Graphics supplies such replacement parts for various models of Vandercooks.] The cylinder carriage bearings consist of the bearings mounted to an impression wheel eccentric. These are adjustable from the outside of the cylinder carriage. There are three sets on each side of a Vandercook SP-15 and four sets on each side of a Vandercook SP-20 or Universal I. The top bearings work in conjunction with the roller height adjustments. Turning the eccentric to raise the bearings upward will cause the rollers on that side of the carriage to drop (downward movement). These bearings are adjusted on “print” mode. The bottom bearings control the amount of impression. Turning the eccentric to raise the bearings upward reduces the play in the cylinder, thus increasing impression. These bearings are adjusted in “trip” mode (off impression). Note: Vandercook made its initial settings with the cylinder carriage positioned in the middle of the bed. This is the recommended carriage position when adjusting the bearings. To adjust the bearings, unlock the eccentric’s bolt head and the small bolt head that controls the movement of the eccentric. Turn the triangular-shaped plate to make the adjustment, and tighten the bolt heads.
In adjusting a SP-20, this procedure seemed to work best in affecting drop:
The rear (feed board) top bearing was turned toward the rear to increase drop. The front (bedside) top bearing was turned toward the front to increase drop.
Both bottom bearings were turned toward the front to increase drop.
Note: the direction of these adjustments may vary from press to press.
After re-tightening the bolt heads, check for any drag in the bearings. They should spin with finger pressure and there should be a slight drag on the rail (the cylinder carriage should move without difficulty). The bearings will normally be “loose” in trip mode, but tight in “print” mode.
The cylinder should be packed at a normal setting for the press. Place several long, 36-pt wide, type-high rule down the bed length, one on each side of the bed. A piece of .001 tissue should just pull out from the compression of the cylinder against the rule. [Note: The original specifications for the SP-15 allowed for the top carrier bearings to be set at .005 to .007 for the rear bearings and .001 to .002 for the front bearings, but without an appropriate manufacturer's gauge there is no other practical way of making this measurement.]
If this adjustment is correct, ink the press and pull a proof on tissue to reveal inking and impression. Pull further proofs on heavier stock and examine the backside for impression consistency from one side to another. Re-adjust the bearings to correct inconsistencies.
Check the lay of the cylinder on the ink drum by dropping the roller cage down on the ink drum and then lifting it up again. The cylinder needs to be perfectly horizontal to the ink drum. [Some Vandercook models, such as the SP-20 allow for separate ink drum adjustments, others do not.] There should be an even ink strike-pattern of 1/8 to 1/4 inches from end to end revealed on the ink drum.