Mowing 48" Finish Mower Blade challenge

[Jiminy]

I purchased my PT used. 422 with about 100 hours on a 25 Horsepower Robin, stronger wheel motors, and a few other "upgrades" including a sweet floating seat. Approximately 7 years old. One of the attachments is a 48" finish mower. The middle of 3 blades keeps coming off while mowing. I have fixed 3 times in 1.5 months. It would seem that it is threaded so that it loosens as it mows my uneven 1 acre. Have others had this problem? The outer blades are perfectly fine. Every other attachment has been rock solid. PT indicates they have different mowing configuration now and this deck is unsupported. Their solution, buy the new mowing heads/cylinders and install. I have replaced front wheels and now have no problems with roll off, but this blade is really (finishing school requires omission of this word) me off. Any suggestions. I am going to raise the float even higher if possible.:confused2:

 

[3238dpw]

How is the mower cutting when it is together. I know it is a stupid question but I am wondering if your hydraulic lines are reversed making the mower run backwards. I have seen mowers with the blades on upside down cut kind of good.:confused3: It masks the problem

 

[Jiminy]

Scott, It seemed to be cutting fine. The hoses are male and female, and it appears to be Power Trac fittings. Good idea though. Thanks...

 

[frischtr]

I assume you are using lock washers under the blades? Not sure what the differences are between your configuration and the newer decks.

 

[BobRip]

Have you tried Locktite on the bolt threads. I would think this would help.

 

[woodlandfarms]

Instead of loctite, which I have done and now regret, might I suggest Calk.

 

[toy]

I purchased my PT used. 422 with about 100 hours on a 25 Horsepower Robin, stronger wheel motors, and a few other "upgrades" including a sweet floating seat. Approximately 7 years old. One of the attachments is a 48" finish mower. The middle of 3 blades keeps coming off while mowing. I have fixed 3 times in 1.5 months. It would seem that it is threaded so that it loosens as it mows my uneven 1 acre. Have others had this problem? The outer blades are perfectly fine. Every other attachment has been rock solid. PT indicates they have different mowing configuration now and this deck is unsupported. Their solution, buy the new mowing heads/cylinders and install. I have replaced front wheels and now have no problems with roll off, but this blade is really (finishing school requires omission of this word) me off. Any suggestions. I am going to raise the float even higher if possible.:confused2:

Could it be that the belt is threaded around that particular pulley wrong? Even though the belt may be tight maybe at some point the belt was replaced with either a shorter one or a longer one than what originally came on it in order to either take up the extra length or give it extra length to make it fit tight. If the motor is attached directly to that spindle then maybe it is turning in the wrong direction.

 

[Jiminy]

Guys, I used a new 3/8" grade 8 bolt with Permatex Threadlocker Blue. Red seems to be nearly permanent (like Loctite), so I thought I would go down one level to Blue to see if that will do the trick. If not I will move up the hold scale. The belts and other suggestions seem to be in order. Thanks for all of the tips and thoughts.

 

[J_J]

Have you applied enough torque, using a large wrench or impact wrench. My blades also have a large flat washer between the blade and bolt head. . The blades should be cutting in a counter clockwise direction,looking at the bolt side of the bld, so a right hand thread bolt should tighten up against the direction of force. If the blade hits something, that should also help tighten the bolt.

 

[J_J]

Torque specs, are based on non lubed fittings. Any thread additive, could allow over tightening. You could go well beyond the correct torque for the application.

The torque value is dependent on the friction produced by the threads and by the fastened material's contact with both the fastener head and the associated nut. Moreover, this friction can be affected by the application of a lubricant or any plating (e.g. cadmium or zinc) applied to the threads, and the fastener's standard defines whether the torque value is for dry or lubricated threading, as lubrication can reduce the torque value by 15% to 25%; lubricating a fastener designed to be torqued dry could over-tighten it, which may damage threading or stretch the fastener beyond its elastic limit, thereby reducing its ability to clamp a joint.