The swing arm in a Heidelberg GTO offset printing machine may need to be taken out for adjustments or replacement of parts from time to time. Removing it need not be as dreaded as sometimes happens. In my years of experience with Heidelberg GTO machines, I have come across many experts who get uncomfortable whenever such a task is to be performed for adjustments or replacement of parts. This is because the process is very sensitive and affects colour registration. This activity should take less than 1 hour.
I will assume that the degree wheel and zero gauge, though necessary, are not available for this exercise. Crank the machine to the position where the swing arm is about midway between the feed board and the impression cylinder. Mark the position of the arm on the shaft clearly using a center punch or any other means that cannot easily come off. Make sure the marks are clearly visible both on the shaft and on the surface of the swing arm. It will be returned and clamped to this exact position when being fitted back to maintain the timing of paper transfer between the feed table and the impression cylinder. The three 10MM screws securing the arm to the shaft can then be loosened. It is important and safe to switch off the machine at this point.
Remove the machine guards on both operator and drive sides. On the operator side, the swing arm shaft bearing is secured by a set of three 5MM screws on the machine side frame and a chain mechanism attached to an end piece. The end piece holds the torsion rod that gives the swing arm tension to swing during its operation. Carefully and clearly mark the position of the clamping piece on the shaft. To release the tension, loosen the 5mm screw on the clamping piece. The tension will be released and the arm will be completely free. Remove the three 5MM screws securing the shaft bearing and slide off the end piece. The torsion rod is attached to this end piece and should come out of the shaft together with the end piece.
On the operator side, the swing shaft is attached to a lever and locked with three 5MM screws on to the machine side frame. Carefully remove the 3 screws and detach the lower end of the lever by removing the clip locking it after removing the oil tube. The shaft should now swing freely on its bearings on the side frame together with the lever. With the shaft now free on both operator and drive sides, it can be pulled off the machine on the drive side. Ensure that there is enough space between the machine and the nearest obstacle on the drive side. You may need to turn the machine manually if the cam on the drive side is has blocked the lever attached to the swing arm shaft. Pull the shaft and the lever all the way out of the machine, leaving the swing arm in position. The swing arm can then be easily removed from the machine from the front. For the shaft to slide off and come out easily, it has to be very clean and well lubricated. The swing arm can then be easily worked on out of the machine.
How To Remove a Heidelberg GTO 52 Swingarm