[AT] Ford NAA with aux tranny??

Dudley Rupert drupert at premier1.net
Mon Mar 5 12:38:35 PST 2007


John,

As you probably know, in a tractor without a Howard the Power Shaft, which
is splined on the outside, comes out of the back of the Main Transmission
and protrudes into the Rear Axle Housing maybe a couple of inches.  A
similar shaft driving the rear axle pinion protrudes forward out of the
differential.  These two shafts, which are maybe a foot or so apart, are
connected by a Drive Shaft.

To install a Howard the Drive Shaft mentioned above is taken out and tossed
away.  The Howard is then bolted to the back of the Main Transmission
housing with the two inch externally splined Power Shaft mentioned above
protruding into the front of the Howard.  Since the Howard extends maybe six
inches from the back of the Main Transmission into the Rear Axle Housing a
shorter Drive Shaft is now required.  Note:  This shorter Drive Shaft is
part of the Howard "package" and is different between a TO20 and an 8N.  The
front end of this shorter Drive Shaft is splined on both the inside and
outside.

The Howard Gear Lever on the right side of the tractor has two positions - I
forget what they are labeled on the side cover but just for the sake of the
discussion let's say the positions are labeled "Straight Through" and "Low".

When the Lever is in the "Straight Through" position the shorter Drive Shaft
is pulled forward such that its' inner splines mate directly with the outer
splines on the Power Shaft.  With the Lever in this position the tractor
should behave just as through it did not have a Howard at all.  This is what
I referred to as the heavy duty straight through gear set able to handle the
torque from the transmission Power Shaft.

When the Lever is in the "Low" position the shorter Drive Shaft is pushed
backward sufficiently to disengage it from the splines on the Power Shaft.
The splines on the Power Shaft now drive a couple of reduction gears which
in turn now drive the outer splines on the shorter Drive Shaft.  It is these
gears which are very light duty.

I know this is a ridiculously long answer to a short question but hope it
adds clarity and not confusion.

I am as curious as you as to what you have.  Maybe it is a Howard but it's
hard for me to imagine the shift lever and PTO lever all coming out on the
same side ... it's pretty busy in the bottom of the axle housing with the
Howard extending back over the PTO shaft.

I think Mike gave a good suggestion to contact the factory ... maybe they
offered a different design/installation for the NAA.

Dudley
Snohomish, Washington

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com]On Behalf Of John Wilkens
Sent: Monday, March 05, 2007 8:14 AM
To: Antique tractor email discussion group
Subject: Re: [AT] Ford NAA with aux tranny??

Dudley, what was the use of the Howard heavy duty "straight through
gear set" you mention?     The other issue...I need to determine more
about the aux. trans. that is in this NAA.  I wonder if it is just a
Howard with the shifter coming out the other side (Left) of the
case.  I do hope it is not the light duty Howard rototiller
gearing!  It definitely gives the NAA a slower range in all gears but
when it was running I didn't notice if it changed the rpm of the pto
shaft.      John



At 06:49 PM 03/04/2007, you wrote:
>John,
>
>I have taken three Howards out - one from a Ferguson 20 and two from Ford
>8Ns - and put one Howard in yet another 8N but, as you say, the shift
levers
>always came out on the right side.  There are two shafts coming through the
>back of the transmission housing and into the rear of the tractor - the
>power shaft and the PTO shaft.  If your' tractor has a shift lever coming
>out the left/PTO cover plate then I would guess that it is shifting just
one
>of those shafts but which one is a good question.  Of course we know the
>Howard shifts only the upper power shaft but maybe someone else made a gear
>set to shift only the PTO shaft.  I recall Hupp (sp) making an auxiliary
>transmission for the 8Ns but I thought it was up in the bell housing like a
>Sherman.
>
>Just judging from my limited - but relatively - recent experience I think
>finding a good Howard may be difficult or expensive unless, of course, you
>get lucky.  Of the three Howard's I removed only one was what I would say
>was in good/descent shape.  From what I understand you can't buy
replacement
>Howard gears unless you happen to find someone who has had them stashed
away
>in hiding for a millennium.  The straight through Howard gear set is
>large/strong enough to handle the transmission output torque.  The step
down
>Howard gear set, however, is extremely small and these are the gears that
>have stripped teeth.  The step down Howard was never meant to do anything
>other than move the tractor along with an active rototiller behind.  I
think
>it could more accurately be said that the tiller would be moving the
tractor
>along with the step down Howard merely providing some resistance.  I am
>guessing that the reason so many Howards are "bad" is that guys were
tempted
>at one time or another to actually try and pull something heavy in the low
>Howard gear.
>
>I am sorry to sound negative on the availability of a good Howard ...I hope
>you find that I am wrong.
>
>Dudley
>Snohomish, Washington
>
>-----Original Message-----
>From: at-bounces at lists.antique-tractor.com
>[mailto:at-bounces at lists.antique-tractor.com]On Behalf Of John Wilkens
>Sent: Sunday, March 04, 2007 4:20 PM
>To: at at lists.antique-tractor.com
>Subject: [AT] Ford NAA with aux tranny??
>
>Picked up a Ford NAA that has a nice low range aux. transmission in
>it.  I thought it came as a Ford option but now I'm not sure.  It is
>a gear reduction transmission that is shifted by one lever right next
>to the normal PTO lever (left side).  Was this a standard Ford
>option?  If not, anybody know what it could be?  I don't have it
>running right now and I didn't notice before if this step down
>gearing also slowed down the pto--like the Serman.   I've seen Howard
>transmissions in N series Fords but they all had the shift lever on
>the right side.  Also, anyone know where I could find a Howard or
>even a step down Sherman?   John W.
>
>                     In the wide-open spaces of NE Oregon
>
>
>
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                    In the wide-open spaces of NE Oregon



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