I'm looking at a 2006 used S300 with ~4500 hrs. Current owner never used auxiliary hydraulics. Does presence of third hydraulic coupler (case drain) on lift arm along with High Low light on deluxe control panel mean the machine definitely has high-flow? Is there anything to check confirm regarding auxiliary hydraulics condition with no hydraulic attachment to test them with (rentals are 10hr one-way drive away)? Do the auxiliary and high flow auxiliary hydraulics use the main pump that also drives wheels and lift/tilt, or separate pump(s)? In other words, does the fact drive and lift/tilt all work mean the only things left that could be wrong with aux and high flow would be limited to electronics, valves, leaks, or is there a costly component in the aux / high flow system that could be bad and no way to know without a hydraulic attachment to test it with?
Can't answer the Bobcat specific part. Case drain doesn't necessarily mean high flow on some brands, I believe Bobcat is the same. Skid Steer hydraulic systems are basically the same for the most part across all brands. Things are mounted and controlled differently, but the concept is still basically the same. The engine drives a series of pumps. Two variable displacement piston pumps (one for left drive, one for right drive) and a gear pump that is often referred to as the charge pump. When you move a drive stick, you are moving the swash plate in the piston pump for that side which controls the drive motor for that side based on the position of the swash plate (Pilot and EH controls do the same thing just with different controls). The drive pumps are often "charged" somehow either on the pressure or return side of the gear/charge pump, but can operate in a somewhat closed loop, the charge portion is to makeup for the drive motors leakage to the case. The charge pump is the pump that supplies the hydraulics for all auxiliary functions which would include boom/bucket/aux hydraulics. High flow systems on many machines use either an additional gear pump or a two section gear pump to provide the additonal flow when activated. The additional pump/section is always running, just not being added to the system until activated. IIRC the machine you are looking at uses a two section gear pump. While unrelated to the machine you are looking at, some newer machines offer variable displacement piston pumps with load sensing hydraulics for their high flow machines. These simply provide the pressure and flow that is needed (within the specified limit for low flow) regardless of RPM. When high flow is activated, they can provide higher flow and pressure if the attachment needs it. You can usually differentiate these systems as they often run over 4000PSI while most gear pumps are limited to less than 3500.
Thanks for the detailed explanation, durallymax. That all makes sense. Variable piston pump breaking the direct relationship between RPM and gpm would be slick. Dealer looking up by serial number confirmed various other details but couldn't tell me if it was high flow or not. I read elsewhere that the highflow switch on the panel also doesn't necessarily mean it has high flow. If the case drain doesn't confirm either, what does a guy check to confirm high flow / not high flow on a Bobcat S300?
3rd (center) coupler is there as a case drain. the aux couplers are spring loaded to release trapped hyd pressure, so the hose had to be there anyway.... all g/k series machines have the same LH panel, so the button is there for high flow. does the indicator light up when you press the button? if not, then you dont have high flow. as a quick check you can check to see if your aux are working.. start the engine turn on the aux at the panel use the trigger on the RH handle to lock on the aux, (you should hear the engine bog down) squeeze again to disengage using the paddle switch on the RH handle, rocker it back and forth and listen for the engine pull down in high flow mode,( depending on pump condition, and eng RPM) you should hear a (very) heavy load on the engine, @ idle it may even stall the engine. you can also lift the cab and look at the hyd pump itself. depending on how old the machine is, you may have a single hyd pump( belt driven cooling) double pump ( with hyd fan cooling) the HF pump is piggybacked to the outside (rh) side of those pumps the high flow pump has a solenoid/coil on it the only way to really know what the hyd pump is putting out is to connect a flow meter to the couplers :drinkup
Variable displacement pumps only break the relationship to RPM until a certain point. Unless you get PFC(Pressure Flow Compensated) otherwise known as Load sensing hydraulics, the output will be based on pressure only. Much cheaper to have only pressure compensated hydraulics.
Thanks for the tips on confirming HF/lack thereof as well as a basic check of auxiliary hydraulics. HF indicator light does NOT light up when button is pressed. I wondered if it was interlocked with something else (have never used auxiliary hydraulics, let alone HF), or perhaps locked out with owner code (which present owner isn't sure they have). This gives me some other ways to check (unless lockout with owner code wouldn't prevent light from coming on or would somehow give indication of lockout).
like i said, HF was an option, but the button is in ALL the left panels. most operators cant remember their password, let alone how to lock out HF from the panel.... even if you installed, wired, and plumbed in a HF pump, the option still has to be "turned on" in the controller with bobcat service software.... :drinkup
Under cab pictures Sounds like this machine doesn't have high flow. No owner code is presently available, but I did get pictures under the cab. I'm not familiar enough to be certain. Do you see anything below clearly indicating high flow / NO high flow on this machine?
And any idea what that red capped knob (lower right of first pic above and upper left by throttle lever in third pic) is for? I can't figure out what the symbol on it is supposed to mean, and owner doesn't know either. Here's a close-up:
thats the emergency boom down valve. pull up and 1/4 turn to the right will lower the boom with the engine off :drinkup
the 4th pic is the area you want to be looking... but the fuel filler hose is blocking the view to the area of the pump you need to see.... :drinkup
Thanks! I have one picture showing a bit more there, but not sure if it shows enough: Do I need to lift that cab again?
still not far enough to see all the gear pumps :drinkup