Late Model Sunstrand Transmission Question

[Simplicity7013H 95]

Hello Guys, okay so I'm still getting used to my Sovy 18 and how it operates but the transmission operates a bit funny. You have to get the engine up to a good speed before it will start going faster. I took off the spring that goes between the pintle shaft and the frame and operated it then and it's okay but I know the spring is there for a reason so why is it delaying getting up to full speed? 

You help is appreciated,

Elliott

[MikeES 458]

To smooth out the response so it is not so jerky.  

4 hours ago, Simplicity7013H said:

You have to get the engine up to a good speed before it will start going faster.

But I don't understand the above?

[SmilinSam 4,032]

Generally the faster the engine speed the faster the tractor will go when the lever is all the way forward. The engines are meant to be run at full throttle as far as I have read in the owners manuals. The only place I have ever read to run the engine speed at less is for sickle mowers.

In any case you could check the belt tension on the transmission belt. On many occasions the shaft that the idler arm rides on will get rusty and when the brake pedal is pushed the arm will not go back tightly against the belt, or at least tight enough to keep proper tension when running. If this is the problem, will be able to push the brake pedal and let back off, then get off the tractor and you will be able to pull the idler arm up some by hand.

If thats the case, you can pull the idler arm off, punch the sleeve out, polish and clean it, then grease it up and re-install.

You could also make sure that push valves are all the way up, though id=f they are stuck down at all, the tractor generally wont move at all.

Is the tranny filled to the proper amount?

Thats all I got..

Edited October 4, 2016 by SmilinSam

[1978Simplicity7016H 39]

Elliott: I had this problem with my Sovereign and I found this to work.

The black washers are OEM, I put the silver washers on. This tightens up the clip and prevents the whole assembly from moving, which is supposed to do for smoother operation, but by doing this you get full control of transmission speeds. I wish you luck completing this as I had a hard time getting it all back together even with two Vise-Grips. You also must keep the spring in place.

Edited October 4, 2016 by 1978Simplicity7016H

[Mike_H 92]

Mine has had this done previously as well, though they did not do as nice a job putting it back together.  My brackets are bent

[Simplicity7013H 95]

Hello, I tried to put in more washers but I couldn't get the roll pins holding the washers in out of the rod. I'll keep trying. I also put a weaker spring on pintle which helped some. 

[1978Simplicity7016H 39]

When taking the pins out be careful not to smash the ends which would prevent the pin from sliding through the hole in the shaft. 

[BLT 718]

Parts book page 22. Item 32 has a habit of getting loose. Check that out. It might looki a little different on your machine.

http://bsintek.basco.com/BriggsDocumentDisplay/jgEDGP_csH7tG8EPl7mRgtLvBCd6.pdf

 

[Bill725 1,177]

Hydraulic pumps simply provide (2) things, fluid pressure and flow. More engine RPM = more pump RPM = higher pressure and more available fluid flow. Higher pressure provides more power/torque and more fluid flow provides more speed at the rear wheels. The beauty of a hydrostatic transmission is you can run the engine speed at full torque RPM and still vary your speed. The only negative I have found is while rototilling, the tiller can at times push the tractor.

[Simplicity7013H 95]

20 hours ago, BLT said:

Parts book page 22. Item 32 has a habit of getting loose. Check that out. It might looki a little different on your machine.

http://bsintek.basco.com/BriggsDocumentDisplay/jgEDGP_csH7tG8EPl7mRgtLvBCd6.pdf

 

That did it Bob! Thanks a lot! 

[PhanDad 3,622]

Glad to hear BLT's suggestion fixed your issue.

I've also had the "delayed response" issue with several Sundstrand hydros.  Did the cleaning and lube routine on all the pivot points - that would help for a while..  Tried increasing the spring pressure, but didn't like the response (may have tightened it too much).

In a post a while back, someone said replacing the plastic roller that rides in the cam solved the problem.  Even though the rollers didn't look in too bad of shape, I decided I'd try it.  It worked. 

New ones are black and are a little smaller in diameter than the original red ones.  Or maybe the old ones bulge on the ends as the groove is worn in the center.  Some pics:

[CarlH 419]

I purchased a length of Teflon tube with appropriate OD and ID from McMaster Carr.  Not very expensive as I recall.  I now have a lifetime supply of replacement bushings!

[MikeES 458]

I have also found that the roller is critical to smooth and positive operation.  With a good roller you can use the benefit of the spring box to get smooth transitions, (instead of locking up the spring box) and get the speed control you need.

One of my hydros have a hole in the rod on the outside of each end of the spring box that I have put in a hair pin in temporarily to lock up the spring box, until I got a chance to replace the roller.

 

CarlIH, Do you remember the appropriate OD and ID?

Edited October 15, 2016 by MikeES

[Tarheel 77]

On 10/8/2016 at 9:29 PM, BLT said:

Parts book page 22. Item 32 has a habit of getting loose. Check that out. It might looki a little different on your machine.

http://bsintek.basco.com/BriggsDocumentDisplay/jgEDGP_csH7tG8EPl7mRgtLvBCd6.pdf

 

 Item 32, ( 1650358SM, offset link) is NLA. A few sites online are still showing them. I have 5 to mow today and won't pull my Agco apart until later but I had the exact same problem with the hydro lift and the hole in the bell crank was worn hourglass shaped. The pin is hardened but the bellcrank is soft.  It is my hope that the same will be true of the link on the control lever.

 I have an older, very well used 70 or 7114 I can maybe use the parts off of. I haven't seen this problem in the older machines. I would imagine that flat sided hole is broached into the parts (anyone know what that type hole is called?). Maybe I could buy a broach to cut it.

[Mike_H 92]

its called an obround hole (I believe).   Anyway, I was able to order a bellcrank not that long ago for a hydrolift.  If they are not available any longer, you can weld up the wear, and file the flats back in.  

[bigdog46 2]

If you are having problems with the Sunstrand being jerky, you should also check the bolts that fasten the side plates to the bevel gear box.  There are 3 bolts on each side that require a 5/8" wrench to tighten.  There are 2 behind the pto that you can get to if you engage the pto lever.  If the bolts become loose the hydro starts acting very weird as I found out on my 916H this weekend.