I think what you really need as a start is an Operation & Maintenance Manual. This will help you with the controls and also if you are doing your own maintenance. The Cat Publication reference is SEBU7468. I don't see anything used for sale at the moment but you could download a copy from the Cat Publications web site for $52. Alternatively send a message to member @Deimos and see if he can assist. Regarding a hydraulic schematic I'll send you one. Check your message inbox.