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Loss of power/boggin down

jcbforme

New Member
Joined
Oct 17, 2012
Messages
3
Location
Australia
Hi
Read a thread here bout an 5t excavator with a similar issue to my JCB Robot skidsteer, but they never posted the answer/fix.

In brief, after about 1hr of operation, the loader begins moving slower and slower. It bogs down while loading, and gets steadily worse. Filters have been changed. I have noticed if the bucket is raised while moving, the drive (forward and reverse) will slow to a crawl. Also noted; when lowering the arm/bucket slowly while moving the machine forward, and the ground speed is increased more than just leaving the bucket/arm fixed in one position. Sort of like the release of pressure off the lifting arm, allows the machine to increase ground speed.

Is this a hydrolic problem, or a fuel problem? I would have thought a fuel blockage would make the slowing ground speed evident from start up, not just after an hour of running the machine. When loading, it does bog down from start, but worse after an hour.

Are the drive-chains driven hyrdolically or mechanically?

I guessed it would be lack of power delivered from the engine to the hydrolic pump, but the engine rpm doesnt seem to change, unless trying to load/scrape causing it to bog down/almost stall.

It doesnt blow any smoke, unless it bogs down, and that is a black smoke, but it isnt like a cloud or anything. I would have thought too, if it's lack of fuel, then it wouldnt have the black unburnt fuel smoke.

Also, what/where are the pressure relief valves? I did disconnect the low oil switch (which is on low pressure line from the oil tank) but it was doing the bogging down before that (the switch internal oil seal failed, and started leaking oil out of the switch). I have checked oil levels, and all seems fine there.

ok, that's about all I can think of for now. Ok, not so much in brief it would seem, but any help you guys could offer would be great.

cheers
 

jcbforme

New Member
Joined
Oct 17, 2012
Messages
3
Location
Australia
Have you checked the hydraulic filters?

Hi,
Yes, I have checked the hydrolic filter, and only replaced it less than 100hrs ago. I would have thought if it was a filter problem, it would be doing it from cold. But the machine works fine when it is cold, for the first hr or so.
 
Joined
Oct 4, 2019
Messages
5
Location
Canada
I have a JCB Robot 170 with exactly the same problem, just wondering if this thread was ever solved?

I think it's a fuel related issue. Is there another filter/screen other then the main fuel filter element, that could be clogged?
 

Delmer

Senior Member
Joined
Jan 3, 2013
Messages
8,864
Location
WI
Old thread warning!

There's plenty of places that can plug up on anything. The original post didn't sound like a fuel problem or a muffler problem to me.

What is yours doing? if everything is exactly the same, then it's not fuel.
 
Joined
Oct 4, 2019
Messages
5
Location
Canada
So it runs great for about half an hour then loses power and bogs down. It will barely run without wanting to stall, like it's running out of fuel. It's got new fuel and hydraulic filters. If you don't think it's fuel related, what would you suggest?
 

Delmer

Senior Member
Joined
Jan 3, 2013
Messages
8,864
Location
WI
The other one didn't drop engine speed, and blew black smoke when it bogged down, not sure how both of those are possible. What does yours do?

If it blows black smoke when you bog it down, then I doubt it's fuel related. I don't know that system, so I'd get a service manual or start figuring out how it works.
 
Joined
Oct 4, 2019
Messages
5
Location
Canada
Mine drops engine speed but does not blow black smoke that I have noticed. I'll start digging into it, don't have any manual for it
 

Delmer

Senior Member
Joined
Jan 3, 2013
Messages
8,864
Location
WI
There's plenty of places that can plug up on anything. rubber hoses, any elbow or fitting, screens in the tank or inlet of transfer pump, leaking hoses sucking air, garbage floating around the tank. Yours does sound like fuel.
 
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