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I got bored (again)

Discussion in 'Heavy Equipment & Pavement' started by bobcat_ron, Jun 26, 2009.

  1. Tigerotor77W

    Tigerotor77W LawnSite Bronze Member
    from Germany
    Posts: 1,891

    Ooops. I meant closed-center. Am I making any sense at all? I guess I meant to ask whether most SSLs are open-center systems, not open-loop/
  2. Total Earthworks

    Total Earthworks LawnSite Member
    Posts: 21

    My understanding is that the Komatsu utilizes a unique Closed loop load sensing system with integrated power control within the hydraulic system. Certainly having test driven various other skid steers such as ASV's, cats etc significant difference is noted in the way the machine manages anti-stall. Other machines give the clear indication that anti-stall is managed through the fuel pump resulting in significant variation in engine rev's and power when bogging into a pile. The komatsu maintains constant engine rev's and instead varies the hydraulic flow to match speed to load, accordingly, as the load increases when bogging into a pile, the hydraulic system reduces the speed of the machine, slowing rotation of the wheels and increasing torque and traction. To some this may appear as being under powered as it will not spin the wheels, however what it does mean is consistent full buckets, minimal tyre wear, less ground disturbance and less shock loading on the machine

    From a usability perspective, I prefer the Komatsu

    Just my two cents worth
  3. SiteSolutions

    SiteSolutions LawnSite Bronze Member
    Posts: 1,114

    I don't really think that's accurate. The old rowing-oars skid I had managed anti-stall via my ears and arse directing my arms to push less. The SJC machine I have now manages anti-stall by destroking the pumps, a.k.a. "varies the hydraulic flow". I would imagine Cat does the same thing. I don't have any gadgetry on my fuel pump to vary fuel flow according to load. That's how a Briggs & Stratton lawnmower manages anti-stall. It's called a governor. My loader aint got one of them, and I bet BC Ron's kitty doesn't have one either... but he would be able to tell you better than me.
  4. bobcat_ron

    bobcat_ron LawnSite Fanatic
    Posts: 10,101

    The engine has a governor, that's the adjustment on the injection pump I made earlier this year, even in the exploded pats manual it shows the governor control bolt and the torque sensor below it.

    And that's another thing, the anti stall isn't just a valve like everyone thinks, there's an actual sensor below the drive gears from the injection pump coming off the crankshaft, if that sensor drops to a slower RPM, then the relief between the 2 piston pumps kicks in and it destrokes the pumps.
    But when you do the "turning up" on the injection pump, you are basically adjusting the governor to keep the sensor from dropping down faster, and when you do the anti-stall adjustment, you are increasing the relief and destroke pressure.
  5. ksss

    ksss LawnSite Fanatic
    Posts: 7,129

    One of the issues with these machines is with the pattern selector. To be able to have a pilot controlled skid steer with a pattern changer your having to assume that all flows to all functions including drive wheels are equal, there not ideally. This is why no else has put a pattern changer in a pilot controlled machine, not TK, not CASE/NH or CAT. If you want to switch patterns you have to change the plumbing via a kit. I cant speak of durability but they give up considerable performance to have the pattern changer. I liked several things about the machine. I liked the feel of the pilots, nearly ideal balance between feel, and resistance in the controls. The lap bar I thought was an interesting idea, putting all the guages on there. Komatsu has not made the progress they were anticipating with this machine, at least not yet. That cab forward thing that Komatsu uses and now BC, makes visibility to the back much more difficult at least with the Komatsu.
  6. Total Earthworks

    Total Earthworks LawnSite Member
    Posts: 21

    Not all komatsu's have pattern changes, Mine certainly does not. In fact mine has the benefit of having pilot controls with foot pedals, I find this setup excellent for working with a Harley rake as with the foot pedals I have far greater control over fine movements than I have experienced with pilot control machines where everything is on the joystick. It allows me slowly lower the rotor of the rake in nice and progressively.

    I don't mind the rear vision on mine, with the optional mirrors fitted on the arms I find that I personally have far better vision than I do in say the Cat 299's, Toyota Huskies or Case machines.

    THEse are all personal and subjective opinions of course, for me the machine works really well and would not hesitate replacing it with a new one.
  7. bobcat_ron

    bobcat_ron LawnSite Fanatic
    Posts: 10,101

    I thought I would bump this back up for someone who has contacted me for information on this topic through another forum.

    The injection pump, the long brown cap is the one to look for, use a vise grip to grab it and whack with a hammer, there is C-clip holding the cap on the jamb nut, it is on the left side, on the bottom of the pump:

    This is what it will look like, not my picture) loosen the jamb nut (the one against the pump housing) and turn out the bolt at least 1/2 a turn, and tighten the jamb nut, or rev the engine until you see a bit more smoke out of the muffler, not copious amounts, just a wisp:

    The relief valve on the valve bank, on the right side of the frame:

    ***Loosen the center nut and turn the outer nut out and tighten center jamb nut, test before and after to verify***
  8. CarterKraft

    CarterKraft LawnSite Senior Member
    Posts: 290

    OK Ron you I am fixing to pull your CAT credentials.

    On a B-series and back machine there is no interface from pumps to engine. The engine drives a load and the pumps pump oil. The speed sensing pressure is proportional to engine RPM so.... As engine RPM drops speed sensing pressure lowers accordingly, thus swashplate angle is minimized and consequently so is flow. Pressure and power remain the same but flow drops causing a reduction in speed. The pump governor is trying to maintain the engine RPM at the predetermined torque check level yielding max engine torque. Again no connection between the engine fuel settings and pump controller. No sensors solenoids etc.

    Now when you raise the speed sensing pressure you are fooling the pump into basically raising the point the anti-stall kicks in, or eliminating alltogether bcuase the destroke doesn't happen as aggressivly.

    You can S-can it all together if you want by moving some lines but why?
    if the tires spin how much power do they put to the ground? Do they wear tires faster? Do more work?
    I am all for hot rods but watch any operator on any jobsite the rookies are the only ones spinning tires.
  9. bobcat_ron

    bobcat_ron LawnSite Fanatic
    Posts: 10,101

    This was only intended for the guys with track loaders, and OTT units.
  10. CarterKraft

    CarterKraft LawnSite Senior Member
    Posts: 290


    no difference from track to tire either, except of course C-series.

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