My new Allis Chalmers D272 hydraulic question.
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=204867
Printed Date: 02 May 2025 at 10:25pm
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Topic: My new Allis Chalmers D272 hydraulic question.
Posted By: John426
Subject: My new Allis Chalmers D272 hydraulic question.
Date Posted: 08 Jan 2025 at 4:51am
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I have just completed my collection of small Allis Chalmers with a D272 model built in England. When restarting, the hydraulic system is very weak. I only lift 300kg. After dismantling the hydraulic pump, the relief spring is broken. After changing it, I measure a pressure of 220 bars. This pump is the same as on the C model. Same part number and spring. But I have no information on the hydraulic pressure of the D272 model. I do not have a service manual, only the parts manual. What surprises me is that the integrated cylinder of the D272 measures 76mm in diameter, or 46 cm², which with 220 bars would gives a force of 9.6 tons and provide a lifting capacity of 1.7 tons. This effort of 9.6 Tons seems very high for this small tractor and for the frame which is the stop for the cylinder. Isn't there a risk of breaking the lifting frame? Any information or experiences on this subject?  
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Replies:
Posted By: TramwayGuy
Date Posted: 08 Jan 2025 at 9:44am
| Are you measuring the bore diameter or the rod diameter of the lift cylinder? I don’t think there is piston packing like on most hydraulic cylinders, so it’s the rod area that counts. |
Posted By: John426
Date Posted: 08 Jan 2025 at 10:06am
It is the bore diameter 3" . There is no rod , it is not a standard cylinder.    |
Posted By: Gary
Date Posted: 08 Jan 2025 at 11:51am
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Hi John For reference only, here is a Link to a picture of the Rear of a D272: G https://www.tamarvintagetractors.co.uk/product-page/allis-chalmers-d-272" rel="nofollow - https://www.tamarvintagetractors.co.uk/product-page/allis-chalmers-d-272 |
Posted By: DiyDave
Date Posted: 08 Jan 2025 at 2:44pm
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220 bars converts to 3190 PSI, if I remember right, CA pump was 3500 PSI max, 4gpm flow rate. Have you checked the flow rate of the pump? ------------- Source: Babylon Bee. Sponsored by BRAWNDO, its got what you need! |
Posted By: Les Kerf
Date Posted: 08 Jan 2025 at 8:10pm
Just looking at the pictures it would appear that the relative lever ratios will reduce that lifting capacity by a significant amount. 300 kG may not be too far from reality.
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John426 wrote: