PDA

View Full Version : WALKER MDDGHS GEar Box Problem


70stang
06-16-2007, 04:17 PM
Just purchased a used 1999 MDDGHS with a little ov 1000 hours on it.
Thrid time I did the lawn (great job) I noticed a oil slick on the lawn when I was almost done.
Checked out tractor found main PTO gear box, empty and dripping oil on floor.
Removed mower and I can clearly see a crack on bottom front corner of box.
Now interesting this PTO Box looks new (nice and clean)and the I found two of the four bottom mounting bolts to be loose.
Could this have caused the crack?
Is this a common problem?
Now what is the trick to removing this gear box from the tractor?
There seems to be no room to get this thing out?
Do I need to remove the blower or the hydro & wheel drive gear?
Can I purchase just a new case?

Thanks
Paul

tomo
06-17-2007, 04:30 AM
hello, pto box damaged cracked leaking etc
?Is the pto box u have, the earlier version [u can identify if it has a traditional slip on triple groove pulley ]
The later box has a bolt on triple groove pulley .
Apparently the bolt on pto box can be removed out the sideafter pulley is removed
Removing the earlier pto box requires at least blower removal . I personally own a MT unit gaser . It is very easy to remove engine on this model .

If u own a diesel ghs unit the rotation is opposite to the MT ghs .Then there is the non ghs models .If u order part out side of dealer make sure u have correct part no . U will also need the upgraded pulley

The earlier pto casing halves are not available any more .This is a decision from walker as the only places these boxes come from is walker .They are made for walker by american gbox company .

Loose pto mounting bolt is caused by to many objects being hit in the grass ,this causes a shock load in drive train even if the unit is equipped with shear pins . Make sure these r all in good order eg proper specs not high tensile bolts etc

VIBRATION via drive shaft
Secondly is the slip joint in the drive shaft have only minor play or is it trashed
Thirdly The quick release coupling on the end of the pto out put shaft .
On the mating surface splines are they worn causing even minor play . This is another cause of damaging vibration .

The quick release coupling is a crap idea as it is spring loaded . When the vibration starts the coupling vibrates on the adjoing spline causing major wear and potential damage to other parts such as loosening of the mount bolts

This is the most heavy duty box that the american g/box company has in this series

As with other g/boxes on walkers and other machines that use this brand they r not heavy duty enough

Problems with the pto box in walkers is not un common and in the extreme cases bolts will all come out and the box will smash itself to deathand other components .

One can only hope that hydraulic drive to deck is more common in the future .
Nothing wrong with pto system when built properly .!!

The casing halves do not like being removed and over hauled to many times as the bolt hole areas r VERY VERY WEAK they eventually get hairline cracks

If u o/haul cases and they donot require repairs [metal putty etc ]reseal them with
loctite sealant for alloy cases 508 or 510 or512 checkup ,if u use the incrrect type it will leak eventually .The correct type allows 4 flex in the alloy under load

tomo:waving: :waving: :drinkup:
ps the mount can also crack where pto mounts

Have i ever had issuses with the pto box'' you bet ya''

70stang
06-17-2007, 11:01 AM
Thanks for the reply.
I have the latter gear box with three bolts holding the drive pulley groove belt.
I will try removing the pully and see if I can get the box out the side, still looks tight.
This is my first walker and have only owned it 3 weeks.
I think it will be my last.
I have used old BOLENS ( no longer mfg) equipment since 1966, they have the same spring loaded quick coupling drive shaft-- however they made there own gear box with CAST IRON cases. I never had a gear box issue even when cathing rocks in the snowblower and hitting roots with the mower. Broken blades, bent augers YES, but never a PTO or drive train issue.
I am very sad to see such a nicely designed tractor have such a poor PTO design.

tomo
06-17-2007, 06:18 PM
hello,
If u choose to rebuid make sure the dirt slinger [looks like an extra seal] is located on the out put shaft . If u run without this the output seal faces the front where all the grass debris is flying around and dirt etc will get under seal causing leaks .
tomo:waving:

70stang
06-20-2007, 09:06 PM
I checked the shafts from the main PTO gear box to the mower center gear box.
Not sure which one is bent but whenthey are coupled there is a large bend, a good 1/2 in the center.

So now I plan to order new Main PTO gear box and both shafts to the mower.

Started disassembly, had a lot of trouble getting shear pin out of shaft on mower end. Now I cannot get the shaft off the mower gear box shaft.
Will not budge.
Shouldn't this just pull off?
Any idea?

Thanks
Paul

tomo
06-21-2007, 04:01 AM
I checked the shafts from the main PTO gear box to the mower center gear box.
Not sure which one is bent but whenthey are coupled there is a large bend, a good 1/2 in the center.

So now I plan to order new Main PTO gear box and both shafts to the mower.

Started disassembly, had a lot of trouble getting shear pin out of shaft on mower end. Now I cannot get the shaft off the mower gear box shaft.
Will not budge.
Shouldn't this just pull off?
Any idea?

Thanks
Paul

hello
the shaft that is attached to the pto output shaft has a quick release coupling .If u push the collar [a thin large washer either forwards or backwards it releases the spring loaded ball so u can remove coupling ]The only other reason this will not come apart is if the splines are binding from excessive wear[generaly it does become a looser fit ]

please buy a manual for both parts and service 4 your model . These will be a huge help for becoming familiar with your machine and importantly it also has some specs that will be important . EG pto belt tensioner adjustment
and hydro motor tracking adjusment procedure


tomo:waving:

70stang
06-21-2007, 08:10 AM
I know the shaft connected to PTO is a quick release coupler.
I have that side off.
I talking about the shaft that connects to the mower center gear box.
The side with the shear pin.
I had a lot of trouble getting the shear pin out, finally got the pin out and now I can't the drive shaft (which is bent) to pull off from the Mower gear box shaft.

I have the manuals, it just shows pulling the shear pin and the shaft sliding off.

Thanks
Paul

tomo
06-21-2007, 09:54 AM
hello,
there is 2x pins u need to remove from the yoke . [one end takes uni and other fits onto input shaft ,female hole ]
One pin u remove is the saftey pin which fits not to tight in most cases.Although it can deform making it difficult to remove . Its function is to transmit the drive . It installs thru one side of yoke then thru the shaft and thru the other side of yoke .From memory a split pin is installed once installed


The second pin actually retains the yoke on the input shaft to deck box in the advent u breakthe shear pin. This must be punched thru also . Difficultto explain on web . Once u have apart u will see
A groove is machined in the deck input shaft [around the shaft ]
The ""retainer pin"" enters the side of yoke and passes thru the grooved are a and back out other side of yoke . When u pull on the yoke it pulls the pin up against groove machined into input shaft .

Once apart the yoke should fit on the input shaft without to much slop.
When they have reasonable play shearpins can break more often [components work on ythe pin ] Generally if there is a heap of play it has broken many pins . The wear is caused by the yoke spinning on the input shaft.


tomo:waving:

lucforce
06-21-2007, 11:57 PM
I have to disagree on the gearboxes being "under-designed." If it looks like a shiny part as mentioned, then I would assume that it has been replaced. This is the case, I would then assume that it was not properly installed (loose bolts). At only 1000 hours on the machine, I would further assume that the machine has not been properly maintained and serviced. I say this because the Walker will live with the original gearbox much beyond 1000 hours if maintained. Additionally, we can not really say that the machine was well maintained if there are parts falling off of it.

That said, you will have a hard time locating the bare cases. You would just about have to find someone that is parting a machine out.

Your shaft must be rusted in the splines.

tomo
06-22-2007, 12:55 AM
I have to disagree on the gearboxes being "under-designed." If it looks like a shiny part as mentioned, then I would assume that it has been replaced. This is the case, I would then assume that it was not properly installed (loose bolts). At only 1000 hours on the machine, I would further assume that the machine has not been properly maintained and serviced. I say this because the Walker will live with the original gearbox much beyond 1000 hours if maintained. Additionally, we can not really say that the machine was well maintained if there are parts falling off of it.

That said, you will have a hard time locating the bare cases. You would just about have to find someone that is parting a machine out.

Your shaft must be rusted in the splines.

hello, industrial gearboxes
have dowels locating both casing halves
bearing preload by shim adjustment etc
casings are not typically made from alloy or at least when they are have 3/8 inch thick casing
better mounting bolts that pass thru casing to sandwich box to its mounting
The pto box fearures none of the above :hammerhead: :hammerhead:

quick release coupling although good idea in practice this is where the problem starts .Coupling needs to be held firmly on shaft but still easy to remove . A spring loaded ball does not hold coupling firmly

Universal joints and the bearings in the pto are at max rpm of the specification listed by there makers .Running a unit at 100% does not encourage long life

The shiny situation u r talking about can also be caused by excessive oil leaks washing case alloy .Common when bad oil leaks r present .

On machines that ""have not"" seen regular maintenance pto box [including the drive to deck components ] failure and excessive wear and tear is common .

Late model cases available from walker or complete unit either walker or aftermarket suppliers

The same with the gasers i have seen engines fail at 6oo hrs also although not that common, engines failing at 1000hrs is typical if maintenance is poor

If maintenance is important as 70 stang is discovering it cannot be underestimated with a walker .
WALKERS R A HIGH MAINTENANCE MACHINE

TOMO:waving:

tomo
06-22-2007, 04:53 PM
hello, how did the pto box o/haul/replacement go ??

tomo:waving:

70stang
06-22-2007, 07:48 PM
Still waiting for parts to be ordered. Since I am doing the work myself dealer will place order until he has a order himself.

I cannot find just a case, however I know have everything disassembled.

I opened gear case and everything inside is in "like new condition".
As you said before case is light duty no keying dowels.

I can easily flip the case, wich would put the small hole on top which could be easily migged and sealed with an adhesive type sealer. (we use it on cars in low pressure applications)

In looking at the case the bolt holes are much deeper then the bolts I removed.
I am wondering if the problem was caused by improper size bolts.
The bolts I removed were 5/16-18 x 5/8 long.

With the thickness of the frame that leaves very little bolt holding the box. The box cracked exactly at the end of the bolt.

Was lenght bolts should be holding the gear box?

Also after reading the other notes. I want to say this machine appeared well maintained. All oils clean, new filters, no oil leaks, no fluid leaks.


Paul

tomo
06-23-2007, 03:05 AM
hello, check with dealer on bolt length , sounds right but then again? There listings will tell u the length etc
As u can imagine i am being alittle cautious being that i cannot actually see the pto box .
I would be cautious welding case as distortion may cause other issues eg make the bearings not sit corectly . Remember not all alloys can be welded well it depends on the material .
Look for discolouration in the in any runing surfaces.Grey colour where the bearings run not good and especially if there is pitting .Silver to very light grey is ok .
Teeth on gears should not have wear u can feel ,no excessive pitting .Tooth profile should not be ^ .Either side of teeth should beslightly rounded .
Check output spline with a new coupling ,if this is worn replace box.
The shaft that sticks out 4 the ghs blower pulley ,the keyway maybe worn out . This wears when there is alot of play in drive to deck components .
The areas where the the seal runs on shaft can have no marks from seal wear . If it does it will only leak prematurely if u do not have them welded and machined smooth
The cases cannot be flipped .[upper or lower]
Repair case if repairable with a alloy suitable putty """'Devcon"""

I am aware j-thomas carries the one for the MT model but you will require part no from dealer 4 the diesel

post a photo if u can of damage

All my info comes from experience with the earlier box but mine has a very very slow leak. [top up once per 3wks ] Looked into late box the very first time i did box around 2000 . I have now ordered the replacement should arrive this week .I ordered the later pulley also .

tomo:waving:

70stang
06-25-2007, 09:08 PM
Thank you for all your help.

I have learned a lot.
The gear box in my tractor is the newer style and I really do not think it has many hours on it. The seals and gears are like new, no metal filings in the case, no wear at all anywhere.

The 2 case halfs are excatly the same. Except for one half has threaded holes for the 8 bolts to screw into.

I put the bottom on the top, and the top on the bottom. Sealed the hole with Por 15 Epoxy putty, and put everything back together, using Permatex RTV gasket maker for a gasket. (factory used the same thing)

I just need my new shafts to themower and I am all set to go. I did install my old shafts and ran it slowly but you can easily see the bend in them when rotating.

I now believe the box was replaced a short time ago and the shafts never checked. The vibration caused the box to lossen up and crack.

The shafts are in stock so I should have them on Wednesday.

I let you know how it runs with the new shafts.

Paul

lucforce
06-26-2007, 12:19 AM
Good deal.

I would bet that the box was replaced due to that bent shaft.