surging hydraulics

[Steve t Kiraly]

I have a Lull 644D-34. Serial number 00AL25w24. The hydraulics seem to surge every 5-6 second at idle with no hydraulics in use. when I use the hydraulics the surging is harder and about every 3 seconds. does any one have any ideas?

 

[BillG]

Check the nitrogen charge on the accumulator. Also check the charging valve if the nitrogen pressure is ok.

 

[Steve t Kiraly]

Thanks for the reply Bill. I did check for pressure at the accumulator and it only had about a few pounds of pressure in it and a little bit of hydraulic fluid came out of the filler valve
I did order an accumulator rebuild kit for it but I won't see it til mid April. Then I was reading my repair manual and it does state that the accumulator is to hold pressure for the brakes and steering. Do you think this is correct? Or do you have any other ideas?
Thanks for your reply
Steve K

 

[HATCHEQUIP]

check the suction strainer also maybe

 

[BillG]

Thanks for the reply Bill. I did check for pressure at the accumulator and it only had about a few pounds of pressure in it and a little bit of hydraulic fluid came out of the filler valve
I did order an accumulator rebuild kit for it but I won't see it til mid April. Then I was reading my repair manual and it does state that the accumulator is to hold pressure for the brakes and steering. Do you think this is correct? Or do you have any other ideas?
Thanks for your reply
Steve K

Oil coming out of the charge port indicates the piston seals are leaking which also means the nitrogen escaped out the other end. If this were mine I would disassemble it first and check the bore and the piston for scoring before ordering parts. The most important aspect of the accumulator is the useful volume and pressure. You can use any style nitrogen accumulator as long as it meets the spec.

 

[Steve t Kiraly]

Thanks again Bill. Where can I find specs on the accumulator. I do no the one on the Lull is a discontinued part. I will probably have to order a replacement if the piston and tube checks out bad?
Thanks
Steve K

 

[BillG]

Thanks again Bill. Where can I find specs on the accumulator. I do no the one on the Lull is a discontinued part. I will probably have to order a replacement if the piston and tube checks out bad?
Thanks
Steve K

There may be a label on it by the manufacture. If not just measure the internal volume and subtract the volume of the piston and the end caps. The only volume you need to know is piston travel.

 

[Steve t Kiraly]

I will try this Thanks Bill

 

[tractormech]

You had asked about the accumulator function. It does provide reserve pressure for braking in the event of engine failure. Very little volume so steering is not really helped. The orbital steering would exhaust the accumulator in a hurry. It also provides a sort of cushion to the hydraulic system due to pump pulsation. A bad accumulator will make it cycle like crazy just like yours is doing.

 

[Steve t Kiraly]

I would like to thank all of you that responded to this problem. I had a lot of problems findind a compatible accumulator. However I found a NOS one on ebay. But it did the trick no more surging hydraulics. Thanks