[AT] Ford NAA with aux tranny??

[Dudley Rupert]

-----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

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