The vulcanhammer.info Guide to Pile Driving Equipment features the field service manual for the DGH series hammers. Here we find the following advice during the replacement of the piston ram:
Place 1″ (25mm) wide pieces of soluble paper (such as toilet paper) between the piston and lower ring grooves. Push the rings and paper into the grooves. The paper will hold the rings compressed in place and allow the ram to slip into the cylinder. The paper will dissolve or blow out when the hammer is used. (This is only necessary with the small rings at the bottom of the piston. The larger top rings can be compressed with a ring compressor.)
This was an old favourite of Vulcan’s field service manager, Jess Perry. It was intended to be a simple substitute (in some cases, like this one, the only way to get the job done) for a ring compressor, such as is shown at the right for Russian diesel hammers.
However, in the wake of COVID-19, I never thought I’d live long enough to come to the place where the hard part might be finding the toilet paper…