44 Hydraulic system no PSI

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D2Denny

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Trying to complete my D2 for Portland. Last issue is installing blade but there seems to be no pressure in the hydraulics. Some Background. Unit has not been operable in over 8 years. I pulled the pump unit and drained it of old fluid. removed the filter and washed it out and reinstalled. Resealed the input shaft. All new hoses and all the hard lines steamed and blown out. Filled with 5 gal of new hyd fluid. Tried bleeding the cylinders at the hose connection, have fluid but no real PSI. Pulled the block off plate at the valve to switch hydraulics to the rear, drilled and tapped it for a PSI guage with none showing on the guage. Pulled the filter and tried without, still no luck. Shaft and pump are turning. Drained and pulled the front cover, insides look to be clean. The controll arm moves freely. Befor I start disassembling the innards is there a PSI pressure relief valve that could be stuck in the open position?

If I can't get this sorted out in the next day it will come to Portland sans blade.
At least I can ride around on it and maybe pull something.

Also has anybody come up with a reasonably priced filter for a late model 44 series 9W hydraulic system?

Thx

D2Denny

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Tue, Aug 24, 2010 7:59 AM

edb

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Hi Team,
here is a scan from the Cat Hydraulic Controls and Equipment SRB Form No 12914-01 Dated 08-1954.
The valve is a pilot operated relief valve assembly and is seen as mounted on the side of the pump body. Fairly straight forward if you lay out the parts in the order as dismantled. Usually gunk jaming open the pilot operated valve spool.
Others may chime in on the filter issue.
Cheers,
Eddie B.
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Tue, Aug 24, 2010 10:57 AM

Old Magnet

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Reply to edb:

Hi Team,
here is a scan from the Cat Hydraulic Controls and Equipment SRB Form No 12914-01 Dated 08-1954.
The valve is a pilot operated relief valve assembly and is seen as mounted on the side of the pump body. Fairly straight forward if you lay out the parts in the order as dismantled. Usually gunk jaming open the pilot operated valve spool.
Others may chime in on the filter issue.
Cheers,
Eddie B.

Before you go ripping in to it did you try reving up the engine a little. These are vane pumps (selected for the reason they do not put out at low rpm as a feature for low starting loads). Was a little startled myself when this first occurred to me. If you still get nothing then you will have to go in. No option on the filter.

Also what weight oil are you using. Heavy weight can be a little sluggish to build pressure on cold start up.

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Tue, Aug 24, 2010 11:33 AM

D2Denny

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Reply to Old Magnet:

Before you go ripping in to it did you try reving up the engine a little. These are vane pumps (selected for the reason they do not put out at low rpm as a feature for low starting loads). Was a little startled myself when this first occurred to me. If you still get nothing then you will have to go in. No option on the filter.

Also what weight oil are you using. Heavy weight can be a little sluggish to build pressure on cold start up.

EDB
your scan of the pressure relief valve was most helpful. Pulled apart the valve and found some rust in the bottom main valve bore where a drop or 2 of water collected that stuck the plunger. Also found valve # 11 stuck and spring #14 broken. Cleaned it all up, jury rigged the broken spring, and reinstalled along with fresh hyd oil. There was only a very slight improvement. I'm thinking that if the pump is a vane type perhaps some small accumulation of moisture might have rusted the some of the vanes tight in their slots. Could you possibly scan and send along the directions to the pump? Also do you have a parts manual for this 44 hydraulic unit? I'd like to get the part number to the # 14 spring that was broken.

I'm close to getting this 3 year project done here is current photo.

Thanks for your help

D2Denny
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Wed, Aug 25, 2010 7:26 AM

dpendzic

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Reply to D2Denny:

EDB
your scan of the pressure relief valve was most helpful. Pulled apart the valve and found some rust in the bottom main valve bore where a drop or 2 of water collected that stuck the plunger. Also found valve # 11 stuck and spring #14 broken. Cleaned it all up, jury rigged the broken spring, and reinstalled along with fresh hyd oil. There was only a very slight improvement. I'm thinking that if the pump is a vane type perhaps some small accumulation of moisture might have rusted the some of the vanes tight in their slots. Could you possibly scan and send along the directions to the pump? Also do you have a parts manual for this 44 hydraulic unit? I'd like to get the part number to the # 14 spring that was broken.

I'm close to getting this 3 year project done here is current photo.

Thanks for your help

D2Denny

WOW!!--very nice job on that D2!! 👍

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Wed, Aug 25, 2010 8:01 AM

Old Magnet

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Reply to dpendzic:

WOW!!--very nice job on that D2!! 👍

Post the serial number of the #44 unit.

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Wed, Aug 25, 2010 8:30 AM

bryani289swmi

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Reply to dpendzic:

WOW!!--very nice job on that D2!! 👍

Denny,

Very nice job on the D2, I look forward to seeing it at the show!

Bryan

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Wed, Aug 25, 2010 8:32 AM

Cysco

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Reply to dpendzic:

WOW!!--very nice job on that D2!! 👍

That is a very sharp looking D2 ! Good job for sure.

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Wed, Aug 25, 2010 8:33 AM

SpragueM

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Reply to Cysco:

That is a very sharp looking D2 ! Good job for sure.

Part number for that spring is 7F7802, for serial numbers 7W1-7W9365.
The vanes float back and forth through the vane rotor. This spins inside an elliptically shaped housing. Picking up oil in the larger part of the ellipse and exiting it out under more pressure in the smaller area of the ellipse.
If the vanes were stuck the unit would not be able to rotate. More likely that there is excessive wear allowing the fluid to escape rather than become pressurized.
There is also a pump locating pin that can become sheared. Then the entire pump rotates rather than just the vanes and rotor.

Matt

RD4,RD6 ,D73T, #11 Grader, 977F

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Wed, Aug 25, 2010 8:57 AM

edb

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Reply to Old Magnet:

Post the serial number of the #44 unit.

Hi Team,
here are scans for the Vane pump. Grab 'em now before they are removed to post something else. Sorry no Parts Book for the 9W or any 44 HCU.
Again this thing has loaded the scans out of any logical order ~SORRY ~ I have them numbered so you can sort it out yourselves. Bugger, makes a bloke look un-professional !!!!

Hope this helps.
Cheers,
Eddie B.
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Wed, Aug 25, 2010 9:02 AM

Old Magnet

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Reply to edb:

Hi Team,
here are scans for the Vane pump. Grab 'em now before they are removed to post something else. Sorry no Parts Book for the 9W or any 44 HCU.
Again this thing has loaded the scans out of any logical order ~SORRY ~ I have them numbered so you can sort it out yourselves. Bugger, makes a bloke look un-professional !!!!

Hope this helps.
Cheers,
Eddie B.

That's not quite right on the pump vanes. If they stick in the slots in the retracted position the pump will rotate alright but the vanes need to extend to move any oil. Looks like a pump inspection is in order.

edb,
Your're whipping a dead horse...I've complained a couple of times about the picture posting order....and the double wording. This has been going on since the latest BB revision....appears to be beyond the capability of the canned (as in cheapo) program and the administration.

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Wed, Aug 25, 2010 9:37 AM

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