Catching up with the post stream here...let me ask another question. Are the pumps we're talking about variable displacement or fixed displacement? You can tell by looking for either a pilot hydraulic line (a tiny thing) running to the pump or a wire (for an electrohydraulic or EH) system. I suspect that PT uses a cable on the pedals to stroke the pump's pinnel plate in some of their models, and that's OK too (if kinda old school).
On tram circuits, often there is a variable displacement pump. At idle the pinnel plate is in neutral and even thought the pump is spinning (because it has to - it's mechanically connected to the motor) it's not actually doing much if any work. When you engage the drive, the pinnel tips one way or the other to cause a variable amount of flow to the circuit. So it's kinda weird on the tank turns calculation. Technically at neutral you have infinite tank turns (X gallons of tank / ZERO flow of gal / min) but at full pinnel (or stroke) you get the full rated flow. In part this is where duty cycle comes from for tank turns. Sure you'd turn the tank REAL FAST at full stroke, but how often and for how long do you really tram at full flow? Now that said I've noticed that lots of tramming DOES get things toasty pretty quickly on my PT-425, but not concerningly so thus far. It's not like I drive it miles at a time at full wampum....is more like zip to a pile and zip to someplace else kind of a thing.
That said, to some degree you really should design for the worst case situation that was described earlier. So if you are at full tram, full pto, and somehow full work tool effort on the lift / tilt (how? it's probably possible...) your tank turns get realllllllly small and things get hot. Quick. Like dang hot. But in theory that shouldn't happen too often or too long so often a manufacturer will kinda cheat the calculation a bit.
A fixed displacement pump - like a gear pump, a vane pump, or some low-cost piston pumps - operate in an open loop system where they pump all the time regardless of the control positions and just bypass back to tank when there's no flow to a working circuit. That will also produce a relatively low tank turns calculation too, but since the work being done isn't much (just some flow up and down and around but no real effort) you can run your tank turns down a bit lower than I wrote earlier but it can get risky without a good cooler. On some large yellow machines I'm aware of where the tank turns are a bit on the lower side and you're @riding the cooler@ it pays off to periodically pulse the electric cooling fan backwards to blow the crap out of it so you don't get caught out on heat buildup.
On the very largest wheel loaders - like in mining applications - the drive to the ground is usually either mechanical or electrical, not hystat. One of the big reasons for that is in that size of machine the resulting hydraulic tank size would affect the payload capacity of the machine...because that would be a LOT of oil! Those things are really interesting...but that's a story for another time.
