My 330cl boom drops too fast .

[Cat_man320]

Well I finally got the 320 working great....... because of a wire off the resistor down behind the Limp mode switch in the cab .
Just wondering why the boom on my 330 drops so fast and it doesn't really want to stop when you let go the stick. First time i went to load the tandem I almost beat the side off the box . It drops like a rock. Wondering if it could be a weak pressure relief valve on the valve body , or the spring broke.
Can the relief valve for each function be adjusted? its a 330 cl .

 

[Bob/Ont]

There is a drift reduction valve on the boom up and stick out. The one on the boom circuit might be sticking. Take machine where it can drop and not hurt anything, work it up and down, stall the boom up then let it down slowly. Move up and down from various hieghts and see what happens.
Later Bob

 

[uffex]

Good day
To help please check when you raise the tracks if the machine falls to the ground when you let go of the levers.
Re
Uffex

 

[Cat_man320]

Thanks for the replies , I can raise the tracks off the ground with the boom and it will hold but soon as I let it down it drops like a rock., Bob i never got a chance to check the boom as you say . I will let u know what happens when i get a chance to try it .

 

[uffex]

Good day
I suggest the following procedure to establish the fault, first lets take the control aspect. The pressure at the spool cap should raise progressive with the control lever in the cabin.Install a low pressure gauge to the lower side of the spool cap ("T" Connect 0 -100bar). Check the pressure should raise evenly according the the position of the lever. If this is OK you can take for granted that the control is good, if not you may have a lever issue. Next the main hydraulics, according to the schematic I have there are a couple of possibilities, 1/ there appears to be a lock valve between the main spool and that of the feed to the jacket side of the cylinder. Mostly this is located where the boom jacket connection goes into the valve chest, in many cases this consist of a logic eliment which can be removed for trouble shooting but you need to plug the small lines that activate this valve. This valve should completely open before the main spool shifts in that way the main spool controls the lowering speed. If this logic valve is damaged it could be the cause. 2/ we come back the main spool I suggest the following to establish if this is sticking - rest the back hoe on the ground remove and plug the spool control hose to boom raise, with the aid of an assistant move the boom lower control slowly and progressively
with a small tool inserted in the spool cap observe if the spool moves progressively, be aware that the total spool shift is not so very much may be about 12mm (1/2" American money) . If you cannot locate the issue after this procedure please come back to me and I will try to help.
Kind Regards
Uffex

 

[Aron]

do you check the boom cylinder kit?Is it all ok?

 

[Cat_man320]

Thanks for the replies, I really never had a chance to do much investigation on the 330 . Trying to finish up some excavation work with the 320 and 315 and its getting cold here now . here in Newfoundland we have a foot of frost in the ground .
Aron , the 330 can dig, load , dipper in and out and boom up and down great . I think if a seal kit was gone the boom up with full bucket would be very slow , but that is not the case . Its just that when I go to lower the boom with full bucket it drops too fast for me and when i let go of the stick it might take another 3 ft before the boom will stop.

Uffex , thanks for the info , i will try over the winter to see what is going on and take your suggestions and see how far I can get with it. Just wondering .........my 330 got the long dipper stick I think its 14 ft from pin to pin plus a quick bucket detach which would make it close to 16 ft from the boom/dipper pin to the bucket pin. Just wondering if that would have an effect on the control .

Bob, I have to find all the valves and controls , I would love to get a set of manuals , maybe over the winter i'll find a set and do some investigating the winter/ spring

You all have a very Merry Christmas and a prosperous and healthy New Year

 

[CAT385]

Well I finally got the 320 working great....... because of a wire off the resistor down behind the Limp mode switch in the cab .
Just wondering why the boom on my 330 drops so fast and it doesn't really want to stop when you let go the stick. First time i went to load the tandem I almost beat the side off the box . It drops like a rock. Wondering if it could be a weak pressure relief valve on the valve body , or the spring broke.
Can the relief valve for each function be adjusted? its a 330 cl .

kindly check the boom stem spring and pilot pressure for proper modulation otherwise i dont see there could be any other reason for faster boom lowering

 

[Oxbow]

A fellow I used to work for had a 325B that used to do exactly the same thing. I believe he traded it before the problem was solved. It was'nt too bad to run if you stayed on that machine all the time, but switching back and forth was dangerous!

 

[uffex]

Good day sir
The length of the arm should not affect the lower control, longer arms in many cases reduce production and burn more fuel.
Kind regards
Uffex

 

[cjplanthire]

Smart boom causes this function even if its switched off the oil on that particular movement is faster than standard

As far as I know all 330cl and dl models have this function

When you get used to it it really does speed up productivity

Another movement may be the boom out

This may also be slightly faster than standard and you would notice is at truck loading

I hope this helps I know this because I own a couple 330cl and 320cl machines but I'm not a big car fan

Happy holidays and more importantly happy digging