Hitachi EX15

[nic9]

Yeah I dont think its that though .. if as the op says, there no change in engine note on the faulty side, its not getting loaded, but at least he can identify the faulty line and trace it back. Either the oil is going back to tank somehow, or the service isnt being pulled on.

I did mention earlier, that Ive had a fair bit of trouble with pilots before, sticking, in fact Ive posted about it on here, still got to say I'd like to see that pulled and inspected first and foremost, it doesent take much for them to malfunction.

I take it no ones had the slew motor off and apart ? cos those are usually lobe pumps that drive the pinion and all the internal sections are 'timed' if someone hasnt reassembled it properly you get all sorts of problems although also less than likely if it was working.

Keeping things simple, I assume its not a fault caused by some interaction with the boom offset service ? what operates that ? is it a pedal on the floor ? cos the same lever controls it.

Slew motor has never been off since I got it a couple of years ago. Machine was working perfectly and I was loading my trailer when I suddenly found I couldn't swing left.

Boom swing is a pedal and I hardly ever use it but I checked it still works normally.

As mentioned earlier, I've swopped the lines on the control lever so I'm confident the left swing pilot is working normally.

When I swopped P1 and P2 on the swing motor I checked that the dodgy crimp was not causing an obstruction in the hose.

[Muz]

Boom swing is a pedal and I hardly ever use it but I checked it still works normally.

So the left hand control grip doesent operate the boom off set ? I take it its a separate rocker pedal on the floor does that ?

[nic9]

So the left hand control grip doesent operate the boom off set ? I take it its a separate rocker pedal on the floor does that ?

Yes, on the floor.

[Muz]

Yes, on the floor.

Yes but its not a switch, you rock it left to make boom go left and right to make it go right ?

[nic9]

Yes but its not a switch, you rock it left to make boom go left and right to make it go right ?

Yes, that's correct. It's linked by various rods and shafts into the control valve.

[Muz]

Well if you are satisfied the pilot mechanism is ok at the handset, it can only be something preventing the spool from opening, either that or it is opening but the oil is bypassing inside the motor somehow it might be worth while blanking off the hose for left slew and seing if the engine revs drop then ?

[nic9]

Well if you are satisfied the pilot mechanism is ok at the handset, it can only be something preventing the spool from opening, either that or it is opening but the oil is bypassing inside the motor somehow it might be worth while blanking off the hose for left slew and seing if the engine revs drop then ?

That would be worth a try, I'll try tracing the hoses to establish which is left slew since it doesn't appear to be P1 or P2.

[v8druid]

Well if you are satisfied the pilot mechanism is ok at the handset, it can only be something preventing the spool from opening, either that or it is opening but the oil is bypassing inside the motor somehow it might be worth while blanking off the hose for left slew and seing if the engine revs drop then ?

That would be worth a try, I'll try tracing the hoses to establish which is left slew since it doesn't appear to be P1 or P2.

Looks like it's not lines P1 and P2. Swopped them over but still swung right (no left), this time on the left lever.

so you are saying that with P1 & P2 swapped over it still slews right ok ... if you move the stick left ???
if that is the case then it is deffo P1 & P2 driving the motor

there's no interaction between the slew and the boom swing so that can't be presenting an alternate route to tank.

As Muz suggests ... blank off P1 or P2 ... whichever is the left slew P feed and see if it loads the engine?

if it doesn't there are three alternative possibilities ....
(a) the pilot is not opening the spool ,
(b) pilot is opening the spool and the pressure is finding an alternate easier route to tank
or
(c) [and this is connected to (b)] .. the circuit pressure relief valve is dumping pressure to tank, as it's not loading the engine currently.

If that is the case, I'd guess a broken spring or a bit of crap (like a rubber crumb) is stuck in the mate faces in the RV and it's just dumping pressure instantly.

Muz / Nic ...... I assume that this is not a swash plate / variable displacement pump on this lil' beasty



After-thought !!

if it's slewing right fine still, by operating the lever left with the pipes swapped over, then it can't be the valve block or pilot circuits at issue, as they're both working fine?? ..... got to be the motor

[nic9]

so you are saying that with P1 & P2 swapped over it still slews right ok ... if you move the stick left ???
if that is the case then it is deffo P1 & P2 driving the motor

there's no interaction between the slew and the boom swing so that can't be presenting an alternate route to tank.

As Muz suggests ... blank off P1 or P2 ... whichever is the left slew P feed and see if it loads the engine?

if it doesn't there are three alternative possibilities ....
(a) the pilot is not opening the spool ,
(b) pilot is opening the spool and the pressure is finding an alternate easier route to tank
or
(c) [and this is connected to (b)] .. the circuit pressure relief valve is dumping pressure to tank, as it's not loading the engine currently.

If that is the case, I'd guess a broken spring or a bit of crap (like a rubber crumb) is stuck in the mate faces in the RV and it's just dumping pressure instantly.

Muz / Nic ...... I assume that this is not a swash plate / variable displacement pump on this lil' beasty



After-thought !!

if it's slewing right fine still, by operating the lever left with the pipes swapped over, then it can't be the valve block or pilot circuits at issue, as they're both working fine?? ..... got to be the motor

Yes, I was getting round to realizing that too!

It is a swashplate motor - see pic below. Do you think the parking brake could be the problem?

swingmotor.jpg

[nic9]

I could send you the manual if you'd like some bedtime reading - guaranteed to put you to sleep....

[v8druid]

Yes, I was getting round to realizing that too!

It is a swashplate motor - see pic below. Do you think the parking brake could be the problem?

[ATTACH=CONFIG]3630[/ATTACH]

Hmm .... was referring to the pump, but that's even more interesting .. was wondering when I saw the pic of the motor ..... the valve section on the top of the motor may well be having an influence on your problem ...... possibly ... and could well be a source of a free flow to tank for either P1 or P2 ... whichever is the left slew feed?
Do you have any more info. on the exact function/functionality of the beast??

If it was parking/slew brake, the engine'd be loading

[v8druid]

I could send you the manual if you'd like some bedtime reading - guaranteed to put you to sleep....

Always up for a read .... PM me for an email addy Nic

[v8druid]

hard to tell from the sectional pic ...... but looks like there may well be some form of RV in that valve section in the P1 / P2 ports ... bit of crud in a ball seat and yer pressure's gonna be heading straight back to tank ..... also looks to be a case drain line in the motor body .. might be worth trying a pug in it .... briefly .... just to see if it'll go left ?? .... do not blow the motor though ... it needs that drain but there shouldn't be a huge flow from it .

Not a betting man .... but my money'd be on the valve section, if I were, I reckon ........any more info you have on that would be real helpful

[Muz]

Yeah Ive not examined a swashplate drive motor for a slew drive .. only ever assumed they worked from a drive going to the 'input' shaft to drive the pistons and hence create pressure

[v8druid]

Yeah Ive not examined a swashplate drive motor for a slew drive .. only ever assumed they worked from a drive going to the 'input' shaft to drive the pistons and hence create pressure

I'd be guessing that the valve on the top is a dump at stall set up, due to the nature of the operation of the motor i.e. an RV at stall pressure ... bit of crud in the left hand valve and you'd have no drive at all and for it to occur suddenly would also support that theory ?? (perhaps)

the ball valves in the section pic

swingmotor marked.JPG

are 'praps hiding under these ......

swing marked.JPG

???

this is a damned good animation of an in line axial piston motor's function ..... only thing missing which could confuse is the drive spindle .....

I'd assume that there is a separate T line due to the need to be able to dump at stall .....
valving that feature, by conventionally just reversing the line flows could present some significant issues and much easier to just go with an additional/independant T line to bleed pressure back to free tank, as and when the motor reached a stall point

It would explain a lot