Mower deck belt tension

[lotus1967 0]

Just replaced bearings on the Mule Drive Pulleys and now want to avoid overtensioning the belt and burning up another set. Not sure this was my origional problem as they were origional and 22 years old. Anyway, is there a test to set the tension on the belt after removing and reinstalling the deck? My PTO clutch lever sometimes slips out of engagement and I'm worried I've set it too tight.

Thanks for help

[kpinnc 15,721]

I'm certain there is a technical test. That said, if my blades slow down in deep grass, I know they are too loose.

I don't think the mule drive adjustment is capable of adding the required tension to damage those bearings. More than likely, as you said, they were just due a change.

Kevin

[Bow_Extreme 580]

On many applications, belt deflection is generally measured by pushing the belt from a flat surface until you cannot push it any further. The amount of deflection is the distance from the flat you started on until the point you could push no more. I would say personally, maybe 1/2" of flex at the most. I think it's really based on the user and their conditions.

[Duff 206]

My PTO clutch lever sometimes slips out of engagement and I'm worried I've set it too tight.

What year/model tractor are we talking about here?

Some of us have discovered that the PTO lever popping out of engagement is not due to belt tension, but rather to the main drive pulley on the engine having slipped on its shaft so it is running too close to the engine block. This allows the PTO clutch to misalign and can mess up the PTO lever function. There should be at least a full 1/4 inch (experts, correct me on this if I'm wrong) between the engine and the face of the main drive pulley.

As to the bearings on the pulleys you replaced, I tend to agree with the others - it was probably just their time to retire after 22 years, especially if the machine did a lot of mowing. And following up on Bow's suggestion about deflection, I've always been told to check the deflection as he describes, and to do it at the mid-point of the longest section of belt between two pulleys.

Good luck!

Duff :omg:

[W9JAB 156]

You need to know that belts do their gripping on the side of the belt not the bottom, So if you overtighten the belt you just put undue load on the bearings, belts should have approxamently 1/2 inch deflection at the center point. So what will cause a new belt to slip? the pulley or sheave wears out, the walls of the sheave when new are on a "V" taper in time the walls become concaved and surface area is lostd between the belt and sheave. Most belt manufactures recommend that the sheave be replaced or inspected after 3 belt changes.

[lotus1967 0]

Would someone please explain how to adjust the proper tension on the mower drive belt. I've used the tractor for 20 years, removed the deck a minimum of 4 times a season and just replaced the bearings on the Mule Drive pulleys. Through all of this, I have never known, or thought to find out whether, or not, there is a "correct" tension setting for the belt. Is there something other than just "tight"?

Thanks for help

[daemon2525 5]

Like my daddy use to say. Do you want it "tight" or do you want it "damn tight".

[Don1977 605]

I heard the 1/2" rule from the the Wheel Horse Dealer I bought mine from, and that is what I have always used.

The parts list and instructions that came with my base "Adjust the belt by turning the adjusting knob counter clockwise until the two strands of the belt can just be squeezed together with the thumb and forefinger midpoint between the V idler pulley and the PTO clutch pulley"

I have a C120 and that didn't sound right, but I when and checked my belt that's the way it worked. I just mowed some heavy wet grass today.

[gwgdog66 23]

lotus1967,

Mine is a 1975 C-160 (original mule drive pulley and bearings) and I have never had a problem using this method Get someone to help, safety stuff (netural with foot on brake and clutch) run it up to full throttle, engage the mower PTO, and loosen the belt tension until the belt just starts to flop. Then tighten it up just enough to take the flop out.

My grandpa and uncle taught me this. If you get a ruler out and measure the tension as per the manual it is within the half inch travel called for. :drool:

[W9JAB 156]

Go to Grainger.com when you get to the home page look up part # 3hx33 for v belt tension checker it works on 3l 4l 5l a b c d 3v 5v & 8v belts between 10 - 170"

[lotus1967 0]

Duff: The tractor is a 1987 418-8. Thanks for the advice. I'll check the drive pulley tonight. Just mowed the whole yard last night and had no problem, but did apply some belt dressing prior to that.