Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I have a 536.889251 Craftsman snowblower with a hydro trans, it won't move forward or reverse.
When blocked up, it spins the wheels very slowly, but they will stop if I apply slight pressure.
Yes, the belt is properly adjusted.
Any ideas?
Thanks,
Jim

   The speed control rod could be out of adjustment.   The turnbuckle to Shift Yoke length could be out.

 

   The drive engagement cable could be out of adjustment.

 

   Are the wheel locks engaged?

 

   Drive belt pinched by guides?  Upper guide has 1/16 clearance, lower guide 3/16.

 

   Can’t tell from the drawings just how the hydro unit gets engaged.  It looks like Control Arm Extension would be the engagement and I think a cable going to the top of the hydro block for speed adjust.  Check both to see if the dash controls are moving the parts on the hydro.

 

>>>When blocked up, it spins the wheels very slowly, but they will stop if I apply slight pressure.

  

    Not sure what was meant.  It seems like they are spinning before the “slight pressure” which may mean you engaged the drive clutch.

 

1.      Its blocked up.

2.      “It” spins the wheels.  What spins the wheels?  How did the wheels get to spin?  Do they spin on their own or did you do something to make them spin?  

         It’s confusing because you then say when you “apply slight pressure”.  If you are engaging the clutch for the light pressure that implies the wheels were turning before that which they should not.   Maybe the light pressure is you lowered the machine and just barely hitting the ground makes the wheels stop.

 

Thanks for replying.
The trans is getting power via belt, i don't believe the issue is with linkage or tension.
With the snowblower on wood blocks, wheels raised off the ground,  wheels barely spin and will stop spinning when slight pressure from hand is applied to either wheel.
Belt to trans unit is properly adjusted.
I also disconnected control rod to manually move the lever that is connected to trans unit to rule out adjustment issues.

i hope that clears up what i am trying to describe.

   The speed control rod could be out of adjustment.   The turnbuckle to Shift Yoke length could be out. <--correctly set.

 

   The drive engagement cable could be out of adjustment. <-- It is not.

 

   Are the wheel locks engaged? <-- Yes.

 

   Drive belt pinched by guides?  Upper guide has 1/16 clearance, lower guide 3/16. <-- No, nothing is pinched.  I believe the problem lies within the trans unit.

 

   Can’t tell from the drawings just how the hydro unit gets engaged. <-- Lever on right side for forward and reverse, left handle engages trans drive belt.

   It looks like Control Arm Extension would be the engagement and I think a cable going to the top of the hydro block for speed adjust. <--correctly stated.

  Check both to see if the dash controls are moving the parts on the hydro. <-- They do.

     Remote, but one other thing would be the bolt that ties the axle to the hydro drive.  It's a Murray machine and I've seen that break on a Murray friction drive that tied the drive to the axle with a single bolt. 

     No exploaded view in the manual or part number listed for the transmission.  If you dive in post a picture of the internals.

JimmJ wrote:

The cream color of the fluid is usually an indication that there is water in the fluid.   It should be more of a red or red/brown color.  Having said that, the hydro drive systems on blowers
meaning the pump.  Isn't like a car auto trans. where you've got very high temperatures and rpm.  So I wouldn't think that if there is water in the fluid that it's as big an issue as
it would be in a car.  But I would for sure get the specs. and replace the fluid just to be on the safe side.  Or at least call a dealer and ask about the color.

I would also look at the axle shear bolt the that trouts2 talked about.  It should be on the right side of the trans.  Even if you see it there in place.  I would put a wrench on it
and make sure that it isn't sheared.  I've seen them where they look fine, but if you turn one end with a wrench, one or the other ends falls off.

Not the bolt, checked that. When I rotate either wheel, the opposite wheel spins with it in the same direction.

JimmJ wrote:
Did you check the bolt by rotating the wheels?  Or did you actually put two wrenches on the bolt and see if it's still in one piece?
Having both the wheels rotating together doesn't rule out a sheared shear bolt.  Just wanted to be clear about your answer.

Is there a way to check the fluid level? I don't own anything with a hydrostatic transmission, unfortunately. But from what I've read in passing about the ones used in lawn tractors, it sounds like low fluid levels can lead to it slipping.

"Forcing" them also isn't good for them. Such as moving the pedal/lever further when your tractor's ground speed starts to slow down while going up a hill, while the engine speed remains the same. Unlike in a car, pushing the pedal further on a hydrostatic is simply trying to alter it to a higher gear ratio (faster ground speed), which is the opposite of what you need if it's starting to slip. In that case, you want to ease off the pedal and let it climb at its own pace, in a lower "gear", which is easier on the transmission.

I presume a similar scenario for a snowblower would be getting to a big snowbank, seeing the transmission slow down. and moving the lever further to try and speed the machine up again.

On at least some of the lawn tractor hydrostatic transmissions, it sounds as though they are often not rebuildable. So if they have problems, you can try to top off or maybe change the fluid, but beyond that, people apparently sometimes have to look at replacing them. I hope that's not the case here, of course.

Does the machine have a feature to disengage the transmission, to make it easier to roll the machine when it's not under power? I was trying to help a neighbor with her hydrostatic lawn tractor last year, which wouldn't move, and had spent 5-10 minutes checking over the "obvious" stuff, before I noticed a lever on the back, hidden by the bagger. It was to disengage the tranny. Flipped that back into position, and off it went

>>>Not the bolt, checked that. When I rotate either wheel, the opposite wheel spins with it in the same direction.

 

   That would happen with or without the bolt broken as it’s a straight unbroken shaft. 

 

    Unless you just bought this thing or working on it for the first time what happened the last time out?   If something went it probably would have been noticeable the last time out like a snap or grinding of trans internals.  I don’t think the internal gears are keyed.

 

    It’s looking like a broken trans but some head checks would be:

 

    Turn the wheels by hand in neutral with the clutch disengaged.  They should be fairly free.  Note the position of the transmission drive end to axle.

    Turn the wheels by hand in gear with the clutch disengaged.  I would think drag would increase slightly.

    Turn the wheels by hand in gear with the clutch engaged.  You probably can’t turn them without great effort.

     Pull the start rope with it in gear and the clutch engaged.  The machine should move slightly.  Put a mark on the belt and transmission pulley to note movement.  The way your machine is acting I would think you can pull the rope with only a slight increase in effort from usual as the trans internals are slipping for some reason.   The belt and transmission marks should have moved.

 

I was told by a Craftsman tech that the fluid is  not red in these transmissions, it is  almost clear like new motor oil.    As already suggested, make sure that the

freewheel control on the back os the bottom case in in the engaged position.