540 INEDPENDENT PTO

swattley

Member
I have a truck picking up the 70 4000su. it is very cold in midwest where the tract or has been sitting for 3 months they told me they had to take the drive shaft off the brush cutter. either they did not know how turn it off? cansomeone explain how it operates, i have read about the 2 stage clutch but i thought if the lever on rear was moved the pto would not turn no matter how the trans position or gear.
 

4000SU doesn't have 2 stage clutch.
It has independent pto that is hydraulically operated.
Often times in cold weather the pto clutches have enough drag to over power the pto brake or the pto brake is worn out and won't hold.
 
(quoted from post at 21:04:08 02/10/19)
4000SU doesn't have 2 stage clutch.
It has independent pto is hydraulically operated.
Often times in cold weather the pto clutches have enough drag to over power the pto brake or the pto brake is worn out and won't hold.
does the clutch operate the pto at all how does this system work? so i guess the motor is not turning the pto, the hydralic pump. how how does the pto get turned off
 
There is a shaft from the flywheel through the transmissio to the rear axle that drives both the pump and hte PTO. The pump is actually two pumps in one body. The main larger forward section of the pump powers the 3 point lift hydraulics. The smaller rear section of the pump powers the PTO controls. The handle on the left side merely controls a hydraulic valve. When the handle is in the "engaged" position the PTO brake should be disengaged and the PTO clutch should be engaged, and then the handle is in the disengaged position the clutch should be disengaged and the brake should be engaged. The clutch plates are usually slightly warped from usage over time and will provide some drag to make the PTO spin even when the clusth is "disengaged", and the brake usually wears over time so that it doesn't apply as much braking force as it should.

How fast was it spinning the mower and how heavy of a mower is it? Since you say it is very cold there, it is possible that there is water in the system and thigs are frozen such that the brake will not engage and the clutch will not disengage.
 

Yes the engine turns the pto but the pto input shaft (8) is splined to the pressure plate (7) and turns any time the engine is running.
The pto lever is connected to a hydraulic control valve (10) that engages a clutch assembly (3) which is splined to the pto output shaft (1).
This type of pto operates independent of any other tractor operation, it can be engaged or disengaged any time the engine is running regardless of weather the tractor is moving or stopped.


mvphoto31223.jpg


The photo shows the pto turned off with the brake engaged, cold thick oil causing extra drag on the clutches or warped clutch plates can easily over power the brakes holding capability allowing the pto output shaft to rotate when the pto is turned off.

mvphoto31224.jpg
 
Good info for you (as usual) from these
guys.
The one thing I would add or maybe phrase
differently is this:
The pto in an Ipto tractor is not
hydraulically operated.
Rather, it is hydraulically engaged.
I like Ipto but actually prefer Live pto.
What I like about it is you can snap it
out anytime no matter what the tractor is
doing otherwise.
There are a few things I dislike about it.
First, if you get in a jam on any other
tractor you can stomp on the clutch and
that shuts everything down - forward
motion and the pto. And, you can engage
the pto slowly by slipping the clutch.
With Ipto you have to remember which
function you wish to stop - clutch vs pto
or both.
Secondly, if you are running a bush hog
with Ipto you have to remember to idle the
engine way down then bury the mower in
heavy, thick stuff to stop it. If you
don't the mower keeps spinning for a while
and will wear out your pto brake in short
order.
The pto brake is just a cheesy little
thing and nowhere near strong enough to
stop a heavy mower. All it is really
designed to do is keep the pto from
spinning when it is shut off.
Lastly, even if you idle the engine way
down the hydraulic pto clutch really
hammers the drive line of the mower when
it engages.
You can feather it a little but it takes
practice and still hammers a bit.
Ford seems to have had an aversion to
Inching Pedals and feathering valves.
I understand Ford corrected that hard pto
engaging on later models by allowing you
to feather the oil flow to the pto clutch
but on the 1965-1983 4000s and 4600s
they really Hammer the drive line on your
mower when they engage.
People will tell you you can
engage/disengage Ipto any time but you
will learn quickly to Not engage it at
high rpms.
The SUs are very, very good machines
though. They are kind of a dream tractor
for many of us here.
Be glad you are getting one.
 
i agree more i read about the SU, this tractor is going to mean many things to me. first i been trying to find an old ford i can afford for couple years, second something i have not mention, this tractor is almost be given to me it was owned by a best friend i been working with for 30 years, he just passed away at 54, very suddenly. so i will keep it is great condition.
 

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