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HD-21 Converter

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=71634
Printed Date: 27 Jun 2025 at 9:04pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: HD-21 Converter

Posted By: Ray R
Subject: HD-21 Converter
Date Posted: 10 Jun 2013 at 6:49pm

Hi, I need some advise. Own a mid 60's HD-21 with a clutch or torque converter problem. Any mechanics out there familiar with these machines?

The old girl has a wet clutch, torque converter, and power shift trans. Power is slow and weak making it through to the drive shaft. After first starting the engine the crawler will not move (after shifting) but as it warms up will begin to respond but even then does not seem to push like it should.

I have changed to atf and filter, cleaned the screen at the bottom of the torque converter and cussed the hell out of it....no luck. Any ideas?

And Thanks!!
Ray

Replies:

Posted By: James Coons
Date Posted: 10 Jun 2013 at 9:44pm

Hi, welcome to the forum! I'm not familiar with 21 but I'm sure someone will chime in that has a better idea. Happen to have any pictures?

Posted By: Ray R
Date Posted: 10 Jun 2013 at 9:51pm

Posting still pictures is sorta the issue, would much rather post a video of the old thing pushing a pile of dirt.....

Posted By: steve(ill)
Date Posted: 10 Jun 2013 at 10:19pm

THe motor doesnt drag down when you put it in gear ? Depending on the age, these had brakes that apply in neutral. Need hydraulic pressure to release. (steering system oil). Use to get brake band wear and material would plug the filter and cut down oil flow to release brakes or steer unit. AFT may be o.k., but we always used 10 wt motor oil in trans / converter.

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

Posted By: steve(ill)
Date Posted: 10 Jun 2013 at 10:21pm

First thing we always did when we had problems was to get the transmission oil pressure and steering oil pressure at the filters to make sure everything was O.K.

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