The document provides step-by-step instructions for disassembling and assembling the piston pump of a 336D2 excavator. It lists 22 steps for disassembly, removing components like housings, seals, springs, and bearings. The 30 steps for assembly install these components in reverse order, noting things like heating and cooling bearings during installation and using tools to set clearances. Personal safety warnings are included throughout to avoid injury from springs.