Construction and other equipment - 715D Dipper Cylinder

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715D Dipper Cylinder

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=176998
Printed Date: 01 Dec 2024 at 6:30am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: 715D Dipper Cylinder

Posted By: JCS1
Subject: 715D Dipper Cylinder
Date Posted: 22 Dec 2020 at 10:08pm

I have 715D and the dipper
cylinder is being rebuilt. They called today and said my ring cap on the end
of the cylinder has bad threads they are concerned about it staying on
under pressure if they put it back on. They had a hard time getting it
off. Minnpar doesn't have part number on their website, which I got from my parts manual. The shop said
the last ring (cap) they had made was about $500.00. As my 715 is
getting older and parts harder to find, as mentioned in some of the recent posts, that many of the cylinders were interchangeable with other
backhoes. Any ideas on what I might be replace my dipper cylinder with.

Replies:

Posted By: Coke-in-MN
Date Posted: 26 Dec 2020 at 11:58am

For some reason the cap and the threads on cylinder barrel seem to wear or stretch , cast iron cap and steel of the tube become a weak bond .

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"Challenges are what make life interesting; overcoming them is what makes life meaningful."

Posted By: JCS1
Date Posted: 26 Dec 2020 at 2:41pm

We decided to make a new cap if we can't find an easily replacement cylinder at Surplus Cylinders for a reasonable cost. He said the barrel, piston and rod looked fine, but I'm sure after 44 years those threads are stretched out some too and contributed to making the cap hard to get off. Fatigue could be another factor with pressure on and off.

We discussed the possibility of added tie rods. The clamping idea was a good one, reminded me of pipe riser clamps.

Posted By: Coke-in-MN
Date Posted: 27 Dec 2020 at 7:04pm

I would try the riser clamp idea first - or have that cap made and when turned go a few thousands smaller on ID threading

Posted By: LeonR2013
Date Posted: 28 Dec 2020 at 1:30am

What I do in a case like this. Get everything put in place, seals and all. Then lay it in a tank of water on it's side with just a little bit above the water. Use short piece of half inch and weld it to the cylinder below the jam nut. One on each side will probably be enough. Then make a plate to go over the piston against the cap and draw it together. Has worked good for me in the past. I know it sounds a bit difficult but it's really not. Anyway it may give you a starting point Leon

Posted By: LeonR2013
Date Posted: 28 Dec 2020 at 1:36am

I failed to put in the top line that the piece of pipe doesn't have to be over 3/8"X4" long. Just skip weld it three places. Leon