Transmission has little power

[skipper124]

I have a Yardman 13.5HP 38" cut. Model 13AC762F755. The transmission doesn't have power. It will move sometimes on flat level ground but when I get to a slope it slows down and stops. If I get off, it moves again and seems normal. The belts are not that old. I replaced the original belts and the new ones don't have many hours on them. I'm pretty sure they are routed right. They seem to be slipping. I used the part number MTD give me for the belts. Is there an adjustment I need to make? I always thought they were self tensioned. I noticed there is a copper colored bar down under there that has threads on the end with no nut on it. I don't know if that could be it or not.

 

[Rivets]

First, the belt numbers you should have used as replacements are 954-04001A and 954-05040. Second, did you make sure that the variable speed pulley was moving freely up and down, before installing the new belts? Third, did you make sure the tensioner pulley, part number 62 on the attached diagram, is in good condition and the tensioner arm is moving freely. Any one of these or a combination will cause your problem. https://www.partstree.com/models/13ac762f755-yard-man-lawn-tractor-2007-walmart/drive-2/

 

[skipper124]

I can't remember it was so long ago. I had Lowes order me the belts for it. Think it would be worth it just to change them again? When you say does the variable speed pulley move freely up and down I'm not sure what you mean.

 

[Rivets]

Part number 63 on the diagram I attached. The center part of the pulley should slide up and down freely with no belts attached.

 

[skipper124]

So you mean vertically straight up and down? It moves forward and backward when I depress the brake. I looked at all the pulleys and they are all moving when I engage the gears. I don't know what else it could be. It just loses momentum when I go up a slope. It don't even have to be a steep slope. Guess I'll try new belts then hope and pray that fixes it. I think I know what you mean now. I watched a you tube video some guy moving that thing up and down between the pulleys. I'll try that next chance I get. Thanks

 

[Rivets]

Variable pulley #63 should move up and down when the engine is running only. Very difficult to see unless you can remove the seat. Please DON’T do that. The tensioner pulley #62 will move forward and backwards when you step on the pedal. What should happen is, as you step on the pedal the tensioner will tighten the drive belt, pushing the center variable pulley to go up. This will change the size of the top of the variable puller, increasing the speed of the variable belt.

 

[skipper124]

I found out what the problem was. That nut holding the main pulley down came loose. I tried tightening it up and it ran better but still won't pull a slope. I'm thinking that hub mount is stripped and I need another one. Any idea how I replace that? Can I do it from the top or will I have to drop the tranny?

 

[MowerNick]

Have you tried resetting the position of the vari pulley? That usually needs to be done if you replace the belts, or the machine stalls while moving, runs out of gas. Put the machine on a flat level spot so it wont roll away. Then get on it start it up. Make sure your shifter is in neutral. Then put your speed control to the fastest speed and let the brake pedal out all the way. You may need to assist it with your foot to make sure it comes back all the way. I usually try that first if the belts dont look too bad. But what rivets said is all good too. If the vari pulley is full of crap or belt dust that could be it too.

 

[Fish]

Make sure that all of the bolts that attach the transmission to the frame are all there, if the ones in the front fall out then everything will flex the more load is on it, like going uphill. And the flexing may let the belts slip.

 

[Rivets]

Should be able to do it from the top. Before getting parts, remove the pulley and pulley hub. Make sure the pulley hub splines are the only part bad. If the shaft splines are also sheared you will need to remove the trannie to replace the shaft.