The Inherent Value Of Hydraulic Circuit Diagrams

As I explained in my previous blog post, in the hydraulics world the ability to read a schematic diagram, and the ability to troubleshoot effectively are often considered to go together, 'hand in glove'. But this is not the case. The ability to read a hydraulic schematic is merely an indication of a certain level of system knowledge--and not a measure of troubleshooting expertise. Furthermore, this means a hydraulic diagram, in whatever its form, is nothing more than a troubleshooting aid.

With this in mind, there are four main types of diagrams which may be used to describe all or part of a hydraulic system, and therefore aid in the troublshooting effort: block, cutaway, pictorial, and graphical.

Block Diagrams show the components of a circuit as blocks joined by lines, which indicate connections and/or interactions.

Cutaway Diagrams show the internal construction of the components and flow paths. Because these diagrams typically use colors, shades or patterns in the lines and passages, they are very effective at illustrating different flow and pressure conditions. This makes them ideal for training purposes.

Pictorial Diagrams are often used to show a system's piping arrangement. The components are seen externally and are usually in a close reproduction of their actual shapes in scaled sizes. This aids in component recognition and identification.

Graphical Diagrams a.k.a. schematics, are the shorthand system of the hydrualics industry. They comprise simple, geometric symbols, drawn to ANSI or ISO standards, that represent the components, their controls and connections. Graphical diagrams are preferred for troubleshooting purposes. A graphical circuit diagram or schematic is a 'road map' of the hydraulic system, and to a technician skilled in reading and interpreting them, is a valuable aid in identifying possible causes of a problem. This can save a lot of time--and money in a troubleshooting situation.

If a schematic diagram is not available, the technician must physically trace the hydraulic circuit and identify its components in order to isolate possible causes of the problem. This can be a time-consuming process, depending on the complexity of the system. Worse still, if the circuit contains a valve manifold, the manifold may have to be removed and dismantled - just to establish what it's supposed to do. Reason being, if the function of a component within a system is not known, it can be difficult to discount it as a possible cause of the problem. Schematic diagrams eliminate the need to reverse engineer the hydraulic system.

But as most experienced hydraulic technicians know, there's usually a better than even chance that a schematic diagram will not be available for the machine they've been called in to troubleshoot. This is unlikely to bother the technician though, because it is the machine owner who usually pays for its absence through prolonged service calls and increased downtime.

Where do all the hydraulic schematic diagrams go? They get lost or misplaced, they don't get transferred to the new owner when a used machine is traded and in some cases they may not be issued to the machine owner at all. Why? Because generally speaking, hydraulic equipment owners don't place much value on them.

So if you own or are responsible for the upkeep of hydraulic equipment and you don't have schematic diagrams for all your existing machines, try to obtain them - before you need them. The nominal cost involved could save you a lot of money in the long run.

Bottom line: failing to keep track of your machine's schematics, or not keeping them up to date, can turn out to be a costly mistake. And I explain six others to avoid in "Six Costly Mistakes Most Hydraulics Users Make... And How You Can Avoid Them!" available for FREE download here.