Farm Equipment - powershift gear selection

powershift gear selection

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Category: Allis Chalmers
Forum Name: Farm Equipment
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=137681
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Topic: powershift gear selection

Posted By: grinder220
Subject: powershift gear selection
Date Posted: 23 Apr 2017 at 9:55am

Which is the better choice for the power train for doing tillage work with a 7040,high rang 2nd gear or low range 6th gear? Both are nearly identical for ground speed.

Replies:

Posted By: Orange Blood
Date Posted: 23 Apr 2017 at 10:20am

I personally like keeping the transmission shafts turning a fast as possible for the desired ground speed selection for heavy tillage, and shock loads. higher speed = less torque for the same work.

Let the two speed and the rear make and take the torque, not the lighter gears of the front.

That being said 6th gear does use the A1 & A2, of which A1 clutch which has the fewest discs and plates of any in that trans, but that is because the torque is less at higher shaft speed (engine speed). On the other hand, 2nd uses C1 and B1, C1 being one of the clutches with the most plates and discs, B1, right behind it with only one less disc and plate.

6th will have the trans operating slightly more efficiently, as the front clutch pack is engaged directly to the input shaft rather than a planetary assembly adding heat.

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Posted By: grinder220
Date Posted: 23 Apr 2017 at 11:54am

That's what I wanted to know, thanks

Posted By: DrAllis
Date Posted: 23 Apr 2017 at 1:22pm

You will have more available drawbar HP in 2nd gear. Hook the tractor to a dyno and check HP in each of the six speed selections and you'll find 5th and 6th are the least efficient HP wise. 1st and 2nd gears are actually more efficient than a P.D. transmission.

Posted By: wekracer
Date Posted: 24 Apr 2017 at 6:04am

What are you pulling that you can run that fast. That's over 7mph. My 8050 with 18' disk likes 5th low. That's 5.5 mph and if I hit a wet spot I need to shift down to 4th sometimes. I have to admit that I've never tried in high range but then I would have no gear to shift down to.

Posted By: LeonR2013
Date Posted: 24 Apr 2017 at 6:45am

Running to tall a gear for the work you're doing will cause the governor to add more fuel, so you can use more fuel to get the job done. Might be a little or might be a lot.

Posted By: DrAllis
Date Posted: 24 Apr 2017 at 7:26am

My advice on running 2nd HIGH is the job should be light enough so there is no need to be shifting down to 1st gear at any time and then shifting back up to 2nd high. Reason?? because the shift from 1st to 2nd is very rough and I personally would try and avoid that under load. 2nd HIGH on a field cultivator works well if the load isn't too great.

Posted By: grinder220
Date Posted: 24 Apr 2017 at 12:24pm

Im pulling a 19ft Krause disc with it with no power issues,in fact I'm only running 2/3 throttle and I'm in clay hills. She handles it just fine.

Posted By: DrAllis
Date Posted: 24 Apr 2017 at 12:27pm

Life is good.

Posted By: automaticdave
Date Posted: 24 Apr 2017 at 1:39pm

I use low range then if I need to back up I don't need to shift from hi to low.