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Lou1982

Intermittent Blade Engagement

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Lou1982

Hi Everyone, 
I am new...my brother gave me a used Toro 71225 16-38HXL to cut grass for my new house. It starts great and looks to be in fairly decent condition. Did my research and replaced things like the oil, fuel filter, air filter, spark plugs, and blades to give it a "tune up". I also noticed that the gas tank cap had a cracked, so I replaced it as well. 

So upon using it, I noticed that there appears to be either an intermittent blade engagement problem or maybe the cutting blades intermittently lose velocity - not sure which of the two is happening. I can tell when this happens because the mower gets quieter while riding and then cuts less. When the blades appear to be re-engaged, the mower gets louder and the cut on the grass is perfect. My first instinct is to check the drive belt for stretching by removing it, but before I did this I wanted to see if I was barking up the wrong tree. Upon inspecting the belt while it is installed, it doesn't appear to have any visible damage on it.

Any ideas would be greatly appreciated. 

Thanks in advance, 
Lou

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boovuc

I don't know the 16-38XL vertical shaft at all so I don't know how the blades engage. If it has an electric clutch, I would be looking at that first. If you engage a lever to engage the blades, then I would be looking at that belt or pulley system. Also since you changed the blades, make sure they are on tight and didn't loosen up. Centrifugal energy will spin them if they aren't in high grass. When you get in high grass, they will lose rotation. Slow down or get into low grass and they will spin up again.
That's all I can give you but there are some guys that own this model and they should chime in soon.

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oldredrider

The 16-38 models engage the deck with a lever. Lever is connected to a cable that tensions an idler pulley on the deck. It's possible the cable needs to be adjusted at the deck.
On this, and similar models, all mounting points on the deck HAVE to be properly adjusted for everything to work right. Downloading a manual would be a good start to understanding the operation of the mower. I'm sure there is one in the files section of the forum. The 12-16 xl and hxl models are similar with the difference being horsepower and transmission type.

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Lou1982

Thanks everyone for your responses!
Paul is correct that it has a lever with a cable that when raised engages a tensioner pulley to remove the slack from the drive belt. 
There is the drive pulley from the motor, the pulleys for each of the two blades, and then the tensioner pulley all connected by the drive belt. The pulleys all appear to be in good shape.

I located the adjustment point for the PTO cable. Does anyone have a basic rule of thumb on how tight the belt should be? I looked in the manual and did not find any information on this. 
What I did to check the tightness of the belt was engage the PTO lever, and then bull the belt by hand. I was able to move the belt. When I did this, the pulleys from the blades spun, but the belt slipped over the engine pulley. The belt was not installed tight enough to spin the drive shaft. I dont find this surprising, but should the belt be installed tight enough such that you cannot pull it by hand?  I have a lot of experience working on cars...I cant physically move a serpentine belt by hand when it is installed and the tensioner pulley is engaged. Is how the drive belt on this tractor is supposed to be tensioned?

Thanks for your help!
Lou

 

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bmsgaffer

You should not be able to spin the belt without turning the engine pulley.

On the horizontal shaft engines the rule they use is that when tight, there should be less than 1" deflection when you push on the belt. Im not sure if that would apply here, but the idea is that it should be pretty tight.

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stevasaurus

I like the 1" rule of thumb...try that first.  You don't want it so tight as to mess up your pulley bearings over time.  :)
BTW...Welcome to Red Square.

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Lou1982

Thanks guys! I will give that a shot. 

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Don1977

That system uses a spring to engage the blades. It could the that the spring has got weak,or someone has used the wrong spring.

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