Subject: [Shop-talk] must be mowing season

From: John Innis <[email-masked]>
Date: Mon, 11 May 2015 09:12:40 -0500

Because the grass is tall, my mower is acting up and shop talk is flooded
with mower questions!

Saturday we a rare dry day and I was trying to get ahead of the grass.  Got
almost done when the mower started acting up.

The mower is a circa 2000 Grasshopper 725K will less than 700 hours on is
since new.  This unit has twin "Gemini" (Eaton) hydrostat units, one for
each drive wheel.

The left side is working great, but the right side is running VERY slow in
forward.  It seems ok in reverse, but with the drive controls all the way
forward, the left side is going MUCH faster than the right.  Traveling in a
straight line with the right control all the way forward, the tractor speed
a much slower than it has been in the past.

I checked the linkages, adjusted the neutral point, checked the hydro fluid
and brakes, and found no issues.  Fluid is full, belts are in good shape
with no evidence of slipping.  I lifted the frame up and confirmed that the
speed difference occurs even if there is no load on the wheels.

New filters and belts are on order, and will be installed with new fluid
when they arrive, but I suspect they won't solve this issue.  The thing
that is bugging me it that the transmission seems ok in reverse, so likely
not a clogged filter or slipping belt issue.  Also seems like it's not a
pump or motor problem, as one of these being weak would likely be weak in
both directions.

I have been warned that tearing this hydro down is not a job for a the home
mechanic, but even if I get brave, I'm not sure where to look.  This unit
doesn't work anything like the hydros I have serviced in the past.  Anyone
on the list have any ideas or helpful troubleshooting tips?

John Innis
Cedar Rapids, IA

-- 
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= Never offend people with style when you   =
= can offend with substance --- Sam Brown  =
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Archive: http://www.team.net/archive

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From: [email-masked]
Date: Mon, 11 May 2015 10:13:23 -0400 7.0.1|January 17, 2006) at 05/11/2015 10:13:27, Serialize complete at 05/11/2015 10:13:27

John asks about his mower's 'uneven' speed.

John, I'm not a hydro guy, but it seems like this would be the drive 
motor.  (I would also look at the throttle linkage for both sides, but you 
said you checked that.)

The motor is the only thing that would be single sided. 

I've also heard that they are not for shadetree repair.  (but I've also 
heard they rarely go bad since they are constantly lubricated.)

I know that's not much help, but I would try to put pressure gauges on the 
feed lines for both drive motors.  If they are the same, you have a bad 
drive mower.

Sent from my Commodore 64 on a 2400 Baud Modem.
Eric P
"Be as beneficent as the sun or the sea, but if your rights as a rational 
being are trenched on, die on the first inch of your territory." Ralph 
Waldo Emerson 
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From: John Innis <[email-masked]>
Date: Fri, 15 May 2015 18:25:29 -0500

Well I figured out my problem, some additional troubleshooting showed that
the right side hydro unit (combined pump and motor) was running slow.
Input speed was the same at 3300 RPM on both sides but the right side maxed
out at 70RPM output where the left was over 100RPM.  Changed filters and
fluid and checked the hoses.  Found nothing.  Pulled the transmission.
Eventually got the transmission open and found the the pump cam ring
cracked.  Never seen one break like this.  Parts on order, meanwhile the
grass continues to grow....

On Mon, May 11, 2015 at 9:12 AM, John Innis <[email-masked]> wrote:

> Saturday we a rare dry day and I was trying to get ahead of the grass.
> Got almost done when the mower started acting up.
>
> I checked the linkages, adjusted the neutral point, checked the hydro
> fluid and brakes, and found no issues.  Fluid is full, belts are in good
> shape with no evidence of slipping.  I lifted the frame up and confirmed
> that the speed difference occurs even if there is no load on the wheels.
>
> I have been warned that tearing this hydro down is not a job for a the
> home mechanic, but even if I get brave, I'm not sure where to look.  This
> unit doesn't work anything like the hydros I have serviced in the past.
> Anyone on the list have any ideas or helpful troubleshooting tips?
>
> John Innis
> Cedar Rapids, IA
>
> --

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