It doesn’t have a dedicated PTO tach because the rpm proportion is constant for geared pto’s - and near enough to a constant for hydraulic ones.If it's not clear, your machine has some engine speed for which the PTO will turn at 540. Since the engine probably has a tach and the PTO probably doesn't, you have to find this engine speed somewhere, such as the manual or on a label somewhere. For my machine it's 2510, but yours will probably be somewhat different.