I'd say it will develop as you go...all depends on what specific work you get into and how well supported the line is (special tools provided by the shop / mfr).
A couple of things come to mind, though:
Pressure gauges / assorted adapters for testing hydraulic systems.
Optical tachometer for checking power transmission (pulleys / shafts) speeds.
Big adjustable wrench for odd hydraulic lines / fittings (some are cast pieces neither metric or standard wrench sized)
Assortment of cheapo wrenches to cut up / weld to in order to make special / limited access tools.
I have just recently started to add on a lot bigger metrics (over 21mm) as that is getting more and more common.
^^^ sounds about right.
When looking at crows feet make sure they have the indent in the drive square for a locking detent, or find a set of locking extensions that work with them. It is a true PITA to be fishing around in the belly pan of some huge unit with a flashlight and magnet trying to retrieve them.
Most shops have gauges, get your own digital 0-10000 psi that has a min/max memory for setting and adjusting relief valves. As you become familiar with your common brands of jobs collect the couplers you need, get a -4 (min 6000psi) hose made up, I have 3', 6' and 15' ones that get used regularly. Find a clean tub, toss all of the hydraulic fittings and caps/plugs that you aquire during installs in it, they will save your *** on that oddball job that no one has the right connector for.
It is an expensive purchase but do not cheap out (I dont mean you have to buy truck brand though) on your large wrench set, I use 1-3/8" to 3" a few times a week. But I have a huge range of equipment come through our shop/field calls. It may be wiser to buy them individually, depends on the situation. A LARGE (4" jaw) adjustable wrench is a great thing to have.
If you do a lot of hydraulic cylinder rebuilds a large heavy duty chain wrench is great for removing rod guide caps if the shop does not have a cylinder bench hydraulic wrench (a must for most cylinders larger the 4" diameter) some of the piston end nuts on a large excavator cylinder are torqued to 1700+ Ft/Lbs.
Take a look at the kits the seasoned guys in your shop are using, some will have huge collections others not more then basics. My personal rule is if I borrow it more then once in a 3 month period I start shopping for a good deal, if I need borrow it more then once in a month I go and buy it immediately, if budget permits. Most shops are pretty good about supplying large specific tools, talk to a lead hand or Forman before pulling the trigger on big ticket items.
