Construction and other equipment - Allis Chalmer HD 7G

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Allis Chalmer HD 7G

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=75960
Printed Date: 28 Jun 2025 at 7:12am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: Allis Chalmer HD 7G

Posted By: delmer
Subject: Allis Chalmer HD 7G
Date Posted: 28 Aug 2013 at 1:38pm

I have a HD 7G track loader that has no 1st forward gear. Everything else seems to work fine. Is there some way to test that the clutch packs are getting pressure to engage? Is this a common problem? Should I be looking for something right away to save time and make this repair efficient?

Replies:

Posted By: doctorcorey
Date Posted: 28 Aug 2013 at 7:00pm

There are pressure taps on two transmission shaft bearing housings on the front of the transmission. Tapping into these will tell you the apply or lube pressure being exerted to each of the four clutch packs. Are your transmission pressure gauges on the dash working? You really need a service manual to properly diagnose this if you don't know the location of the pressure measuring points. I might look in mine and see if I could describe the location when I get home.

Posted By: DMiller
Date Posted: 28 Aug 2013 at 9:23pm

On my own 7G I have lost low reverse, will come and go at times so I suspect seals. I have also a weak high forward, low forward being reasonable which I also attribute to seals as it will connect better at times. I agree with Corey, there are two caps on the lines to the lower shaft support cover, these are the ports of the directed oil for shift on it, the same is true to the upper shaft but these are just pipe plugs.

There are three seals in the housings to direct oil to specific sections of the drilled shafts, either these or the clutch pack piston seals are bad in mine as lube and trans clutch pressures are good just not maintained at those points.