312-8 climbs up but rolls down hill

[squonk 42,855]

As belts wear they get thinner. This is what everybody thinks is "the belt stretched" Belts do not stretch. When the sides wear in too far they don't grip the sheaves so the only gripping point is the inside of the belt which is not designed to grip. When you get the guard off, lets see a pic of the belt.

[daveoman1966 3,829]

Another reason I like my C-160 Auto....  does not free-wheel on down-slopes.  

[Jhatch13 31]

2 minutes ago, daveoman1966 said:

Another reason I like my C-160 Auto....  does not free-wheel on down-slopes.  

I would expect this out of a hydrostatic,  a uni-drive with an 8 speed gear box.....not so much

[Jhatch13 31]

44 minutes ago, squonk said:

As belts wear they get thinner. This is what everybody thinks is "the belt stretched" Belts do not stretch. When the sides wear in too far they don't grip the sheaves so the only gripping point is the inside of the belt which is not designed to grip. When you get the guard off, lets see a pic of the belt.

Heres a few

[Tractorhead 9,108]

If the lower Pict is with engaged clutch, than the Belt is definitiv too loose.

I see a wear on belt undersite, but on that picts i cannot exactly see how the belt fit‘s into the Pulley as @squonk mentioned.
when the belt touches the Pulley bottom on the lower side, than it‘s a to worn belt or even a wrong sized Belt
try a pic along the belt facing to the Pulley, to see how it fits.
but as far as i can see on that Picts it seems it‘s to worn.

 

 

what i see so far is firstly a to loose Belt, that causes in a lost friction,

what explains also your traction loss. 

 

The to loosen belt can be also seen on the upper Pict, short after the Pulley.

there is a lightly wave, what shouldn‘t be.

[Jhatch13 31]

1 minute ago, Tractorhead said:

If the lower Pict is with engaged clutch, than the Belt is definitiv too loose.

I see a wear on belt undersite, but on that picts i cannot exactly see how the belt fit‘s into the Pulley as @squonk mentioned.
when the belt touches the Pulley bottom on the lower side, than it‘s a to worn belt or even a wrong sized Belt
try a pic along the belt facing to the Pulley, to see how it fits.
but as far as i can see on that Picts it seems it‘s to worn.

 

 

what i see so far is firstly a to loose Belt, that causes in a lost friction,

what explains also your traction loss. 

 

The to loosen belt can be also seen on the upper Pict, short after the Pulley.

there is a lightly wave, what shouldn‘t be.

Both pictures were with the clutch pedal not being depressed. 

[Tractorhead 9,108]

Ok, than you found your problem.

 

next thing is solve it.

 

look along the Belt, if it touches the pulley inside with Belt bottom, it‘s to worn or wrong belt size

[Jhatch13 31]

It started storming here so I had to put it back together and bring it inside ( limited space to work it the garage). This is from the front side of the pulley (towards the grille pointing camera towards the rear end). The clutch was not depressed in this picture either. 

[Tractorhead 9,108]

No, i meant from the other side, where the belt is running into pulley.

[Jhatch13 31]

Just now, Tractorhead said:

No, i meant from the other side, where the belt is running into pulley.

I will have to take the belt guard off later and get another picture. Thanks for the diagnosis!

[Tractorhead 9,108]

Try also if there is a play in the belt spanner.

 

The spring must pull the spanner to the Belt with a bit of Force so about 2-4 Kilos.

if there is a play, maybe just your spring is a bit lame

[Stormin 9,983]

1 hour ago, Jhatch13 said:

 

 

 If only light pressure, if any, is on that belt, then to my mind it's well slack. The top will be tight under forward drive, but the bottom will be flapping about like mad.

[squonk 42,855]

23 minutes ago, Jhatch13 said:

It started storming here so I had to put it back together and bring it inside ( limited space to work it the garage). This is from the front side of the pulley (towards the grille pointing camera towards the rear end). The clutch was not depressed in this picture either. 

That belt is sitting too low in the pulley. Replace it

[Jhatch13 31]

47 minutes ago, Tractorhead said:

No, i meant from the other side, where the belt is running into pulley.

Here is the front and rear pulley. Excuse my lack of photography skills. The belt measures 3/8 on the bottom of the "V" and 1 inch on the top. I believe 5/8 is what it should be.

[953 nut 58,370]

it seems to me that the laws of physics can't be overlooked here. When the engine is transferring power to the transmission  the lower half of the belt is doing the work. Your engine pulley is turning counter clockwise PULLING the belt toward it. The belt clutch tensioner is just taking up the slack on the lag side of the belt.

When you are headed down hill the engine is turning the same direction but slower than the transmission so the lag is on the bottom half of the belt and the driven tension is being applied to the spring loaded clutch tensioner on the top half of the belt.

Your owner's manual tells you to avoid steep grades.  Be safe and follow the manufacturer recommendations

.

 

[Jhatch13 31]

53 minutes ago, 953 nut said:

it seems to me that the laws of physics can't be overlooked here. When the engine is transferring power to the transmission  the lower half of the belt is doing the work. Your engine pulley is turning counter clockwise PULLING the belt toward it. The belt clutch tensioner is just taking up the slack on the lag side of the belt.

When you are headed down hill the engine is turning the same direction but slower than the transmission so the lag is on the bottom half of the belt and the driven tension is being applied to the spring loaded clutch tensioner on the top half of the belt.

Your owner's manual tells you to avoid steep grades.  Be safe and follow the manufacturer recommendations

.

 

 Below is what my owners manual says. According to #44, im doing everything that I should be (aside from being able to mow uphill, not ascending backwards) in regards to mowing downhill, and its not working currently. 

Edited June 22, 2020 by Jhatch13

[skrusins 128]

I have several steep hills. I find that if I try going down forward my 312-8 slides and turfs up the lawn even applying the brakes. I go up the steep part of the hill forward and back down backward. I feel that I have more control then I use second gear to finsh the hill.

[Jhatch13 31]

2 minutes ago, skrusins said:

I have several steep hills. I find that if I try going down forward my 312-8 slides and turfs up the lawn even applying the brakes. I go up the steep part of the hill forward and back down backward. I feel that I have more control then I use second gear to finsh the hill.

This hill is fairly long and somewhat steep.  Im afraid that if I backed down it, i may get the same result, or have it flip over and land on top of me.

 

Ill probably just stick with the 211 until it breaks.  At least i know it works. The 312 is in too nice of shape to keep trying and have something break or roll out of control and flip. If i can find a snow blade locally i may keep it for plowing,  but I may just sell it.

[skrusins 128]

Did you try to go up and down the hill at a angle by shifting your weight on the seat instead of straight. I do that on some of my hills.

[lynnmor 7,629]

Hopefully someone will buy it, tighten up the belt and have a good tractor. 

[gwest_ca-(File Mod) 11,284]

If this tractor has a dampener on the idler pulley it is likely misadjusted for a worn belt or the dampener is sticking. The first ones were an air shock and you can wash them out so they work again. It is a dusty environment for this type of shock.

 

Garry

[Jhatch13 31]

3 minutes ago, lynnmor said:

Hopefully someone will buy it, tighten up the belt and have a good tractor. 

Hopefully they wont have any steep grades to use it on. 

 

I dont think that changing the belt is going to make that big of difference as far as my hill is concerned. Everyone who owns the same model seems to have the similar issues, regardless of the belt being new or worn. I would also add AG tires, but if i end up with the same result thats alot of money for nothing.

 

I think that the greater friction from the 211s setup, the lower center of gravity, and the ability to put all my weight over the rear wheels helps versus the larger 312. It just may not work for what I need out of it.  Better that it goes to someone who can use it than to sit or get damaged.

[Darb1964 1,100]

I have seven wheel horse tractors three c series, ten, eleven and twelve HP. With eight speeds. A three hundred, four hundred and two five hundred series with hydro and eight speeds.every one will go up or down a steep grade, I have a hill that is probably a little steeper than recommended and they will go up or down that hill with out free wheeling. I weigh two hundred give or take a few. A three hundred pounder results may be different. I think you need a new belt or adjustment free wheeling is not normal under normal working conditions.

[tom2p 2,394]

have a 312-8 that I've used since late 90's 

 

including up and down hills 

 

no issues - engine / transmission braking works well 

 

do have to be careful when grass is wet and when applying brake though - too much brake and one rear wheel will often lock (and / or begin to spin backward)

best to use brake sparingly or no brake - and allow engine / transmission to provide brake 

 

I use Wheel Horse OEM belt - off-white belt with Wheel Horse and part number stamped on a small black rectangular part of the belt

 

Edited June 22, 2020 by tom2p

[kasey54 305]

I have loaded and unloaded lots of gear drives on much steeper ramps than the tractor should be driven on.

The only time they free wheel is with too little belt tension. If you determine if its a tensioner  problem , or too long of belt

or too worn fix it you will have no issues except traction. Then one wheel will skid or turn backwards. Don't give up on it.