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Model C hydraulic problem

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=208745
Printed Date: 03 Nov 2025 at 7:47am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com


Topic: Model C hydraulic problem
Posted By: John426
Subject: Model C hydraulic problem
Date Posted: 02 Nov 2025 at 10:38am
Hi,

I had a problem with insufficient pressure in the hydraulic lift of my Allis Chalmers C. I replaced the weak discharge spring, which was too weak. Now I have the correct pressure, and the lift functions properly. However, it doesn't hold the load. The cylinder lowers as soon as I release the lever.
The entire pump was disassembled, cleaned, and the balls were replaced; everything seemed fine. There were no marks on the ball seats.
What could be the cause of this problem? 
Is there an adjustment I need to make?



Replies:
Posted By: SteveM C/IL
Date Posted: 02 Nov 2025 at 12:36pm
not familiar with a C but sounds like an adjustment or simply not operating correctly. WD has a hold valve and linkage adjustments needed when not functioning properly.


Posted By: PaulB
Date Posted: 02 Nov 2025 at 5:29pm
When rebuilding the pump, did you replace all of the ball seats? When you replace the seats, you need to take a NEW ball and use a good size punch and hammer to give the ball a solid WHACK. This will assure that the seat confirms to the roundness of the ball. Then that ball gets thrown away and a NEW ball is used on that seat. A new ball must be used in this process for every seat, and in turn that ball gets thrown away and then the next seat...  

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If it was fun to pull in LOW gear, I could have a John Deere.
Real pullers don't have speed limits.
If you can't make it GO... make it SHINY


Posted By: steve(ill)
Date Posted: 02 Nov 2025 at 7:20pm
i had that happen... NO HOLD... when the external friction plate and backer plate ( #33- #34) got stuck together.. I think that spring #14 ( external ) broke... This allows the SPOOL #12 inside to not seat on the flat spot on the shaft #13......  Work the outside plate and see that it moves free, the friction plate is not stuck to it, and it seems to "SEAT" when you release the plate.( feel the DETENT.... The "SEAT" is the relief spool #12  setting on the flat spot of the #13 shaft for the "HOLD - DETENT" position... If everything OUTSIDE is OK... You might have internal  problem with the spool / shaft  / seat face ..




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Like them all, but love the "B"s.



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