shock to hydraulic system?

[bellweather]

I have a BX22 and while attempting to use the FEL, I did not realize that the hydraulic lever was not in the neutral position. The loader would go up OK but the only way to lower it was by jogging the lever into the float position, whereupon the loader would drop and then I would "catch it" by jogging the lever back out of the float position Each time the bucket would jolt to a stop, and I would momentarily jog the lever in and out of the float position until the loader came all the way down. I did this about 6 times while moving some loose top soil (light load).

Obviously, this can't be good for the hydraulic system. My question is, how would I know if I caused any damage? (seems to work OK now, but I can't remember if it used to lower any slower than it seems to now). Is there anything I can check?

Part 2 of my hydraulic question: Is it bad to operate the FEL at low rev? I notice that the hydraulic system whines if the FEL is operated at low rev.

Thanks

 

[Hawkflyer]

While it is not good to drop the FEL using the "float" particularly with a load, (the manual is specific on this point), I am certain you have caused no damage in the few times you did it. The only possible damage from what you describe would be to seals in the control valve or lift cylinders. The only other area would be the hydro lines themselves, and you would know about that right off. If your loader lifts and holds position then the seals are fine.

As to the noise. The pumps make noise all the time. First, you are now looking for a problem that might be the result of the "float" issue, so you are overly sensitive to things you hear. Second, when the engine is running slowly, you can hear the pump more easily simply because it is a quieter overall environment. Also at lower speeds the pitch of the pump is not the same as it is under normal operating conditions, and you will notice the change. It won't hurt it to run slow but it can't do as much work.

If you are relly worried, have the dealer check it out. As for speed of lift, can't help you there.

Good luck!

 

[techman]

bellweather:

Knowing a bit about hydraulics I think I can give you some answers. Running at low RPM will not cause any harm. The reason that the hydraulics sometimes grinds to a halt at low RPM is due to the pump efficiency. All pumps have internal leakage, that increases with load pressure. If you are at low RPMs, the pump is only pumping a small amount of oil, and all of it can go into internal leakage as the load goes up, therefore effectively pumping nothing into the cylinder. As you increase RPMs, the greater oil flow is enough to overcome the leakage and deliver oil to a cylinder (leakage is relatively constant for a given load pressure). For the type of pump used (external gear pump) up to 15% of the total flow can go towards leakage in an average pump, at high pressure. The only downside to all of this is that the internal leakage oil is converted into heat.

As for your FEL situation, the bucket should always try to lower when even lightly loaded, even if the RPMs are low. The fact that it would not could be the same as happened to me. Same symptoms and it turned out to be one of the quick disconnects got popped off. I think a tree branch (from clearing cut trees) hit the collar. It still looked coupled, except that it was just a bit further opened than normal. I saw it, wiggled the hose and realized what had happened, and went to re-couple it. Problem was that the cylinder had generated high pressure in that line, due to the load and "intensification" (two areas of the cylinder increases the pressure), and I couldn't get the halfs coupled. When I would try, as soon as I pushed far enough to open the little internal valve in the coupling, a little shot of high pressure oil would pop the coupling apart again. I had to repeat this step a number of times, each time dumping the small amount of oil that filled the coupling, until enough high pressure oil was relieved, lowering the pressure in the coupling. Then I could finally push it home.

Long story short, check all of the hose couplings.

paul

 

[bellweather]

Thanks for the input guys. You're probably right about being hypersensitive to the noises. I'll see how it goes - if I'm still troubled or suspect something is amiss, I have the dealer check it out.