Farm Equipment - 8070 Transmission Brake Question

Print Page | Close Window

8070 Transmission Brake 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=179066
Printed Date: 03 May 2025 at 5:31pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: 8070 Transmission Brake Question

Posted By: PAFarmer
Subject: 8070 Transmission Brake Question
Date Posted: 15 Mar 2021 at 3:40pm

Hi All,

I posted this in the thread I started about the 1984 8070 I'm considering purchasing and I think it got buried amongst the conversation in there. I test drove the 8070 yesterday, and things seemed good as far as shifting and brakes were concerned. There was some oddity with the transmission brake that I'm hoping someone here can shed some light on.

I think I read that the trans brake is just a combination of the reverse clutch and a forward clutch that is activated when you push the inching valve past the inching position. When pressing the clutch to stop, the engine would come under load like the transmission brake was being applied but it wouldn't stop until the clutch was pushed farther down. Is it possible this is a linkage issue? Is there something else I should check?

EDIT: I forgot to mention, this is a Power Shift transmission. Don't know if the Power Director has a trans brake, but thought I'd add this.

TIA!

Replies:

Posted By: PAFarmer
Date Posted: 15 Mar 2021 at 4:15pm

I spoke to the owner and he remembered that he had replaced the clutch cable, so I'm going to assume that's the issue. I'll follow the procedure in the Service manual and see if that works it out.

Posted By: DrAllis
Date Posted: 15 Mar 2021 at 8:19pm

The transmission brake is supposed to come on when the inching pedal gets within about 2 inches of the bottom of its stroke and then continue all the way to the bottom. If you noticed, there is an increase in effort to push the inching pedal down into this brake "zone". Properly adjusted and with a experienced driver, you can go down just to where this zone begins and feel it in the inching pedal. Any more down than that applies the brake. Warm oil makes things work differently than cold transmission oil.

Posted By: PAFarmer
Date Posted: 15 Mar 2021 at 8:29pm

Thanks, Dr. Allis. As you described it is exactly how our 8010 is. As you say, if you've spent some time running one of these, you can tell in your foot where the break zone starts. On this 8070 the trans brake comes on basically right away. Maybe after roughly 2 inches of clutch travel. I had let the 8070 sit and idle for maybe 15 minutes on a 50 degree day, so I doubt cold oil was to blame.

I read the adjustment procedure in the service manual this evening, and it seems pretty straight forward. I'll try that and see if it straightens out the issue.

Posted By: johnny s brooks
Date Posted: 16 Mar 2021 at 6:37am

I have what I think may be a related problem. I feed silage with a 7045. Moving from one lot to another the PTO brake against the loaded feed wagon pto telescoping shaft exerts enough tension that the shaft remains tight and will not telescope freely. This plays heck with the gearbox, etc. I installed an over-riding pto clutch tp no avail. I disconnect the shaft between lots. Not convenient. Any solutions?

Posted By: MACK
Date Posted: 16 Mar 2021 at 8:35am

Johnny, your problem is PTO shaft. Drawbar is in wrong hole , shaft needs shortened or shaft needs greased or replaced . Are you sure the two joints are in time? MACK