L2800-L3400 PTO Making the right choice

[ccsial]

Ok i'm another 2005 L2800 HST owner, I called my dealer to ask about this problem. He called the service rep and within 5 min. had an answer and got the new one way cams on order, they should be in Friday and I will drop my tractor off next week.

This is also what my dealer said. My tractor is 2 years old. I have always said the dealer is more important than the brand.

 

[RayMunising]

I'm no expert and I don't even play one on TV but don't you think the problem lies in the spring (or whatever it is) that forces the 2 cams together when the PTO is engaged? I don't see how the chatter noise from the original cam design can cause any harm to the cams at all. Noisy - yes! Harmful - I don't see it. Actually the new locking cam is going to bang the backside of the cam tooth instead of sliding up the slope that the old cam had. The old cam would make the spring that forces the cams together really work as the overrunning action was spinning. That wouldn't be the case in the new style.

Looking back at the picture of the damaged cams Hammer posted way back when it sure looks to me like those cams would engage with each other without any problem if they were held together. How could they slip? The only way I can think of is the force that holds the cams together was not sufficient. A weak spring? Does that make sense to anyone else?

One thing that's for sure with either the new or old style cams there certainly is no feathering in engaging the PTO. It's going to engage with a heck of a force!

 

[ccsial]

I'm no expert and I don't even play one on TV but don't you think the problem lies in the spring (or whatever it is) that forces the 2 cams together when the PTO is engaged? I don't see how the chatter noise from the original cam design can cause any harm to the cams at all. Noisy - yes! Harmful - I don't see it. Actually the new locking cam is going to bang the backside of the cam tooth instead of sliding up the slope that the old cam had. The old cam would make the spring that forces the cams together really work as the overrunning action was spinning. That wouldn't be the case in the new style.

Looking back at the picture of the damaged cams Hammer posted way back when it sure looks to me like those cams would engage with each other without any problem if they were held together. How could they slip? The only way I can think of is the force that holds the cams together was not sufficient. A weak spring? Does that make sense to anyone else?

One thing that's for sure with either the new or old style cams there certainly is no feathering in engaging the PTO. It's going to engage with a heck of a force!

Your post got me to thinking. If the tiller is causing chatter, then the slant cam is moving it away from the spring. When is slams back it may happen so fast that the spring does not have time to push the slant cams back and they hit on the edge causing it to round out and eventually fail.

If that is the case the new cams would be much better.

 

[RayMunising]

Your post got me to thinking. If the tiller is causing chatter, then the slant cam is moving it away from the spring. When is slams back it may happen so fast that the spring does not have time to push the slant cams back and they hit on the edge causing it to round out and eventually fail.

If that is the case the new cams would be much better.

If that's what's going on then the new cams would be better but really the cam edges didn't look rounded ... just a little nicked on the edge and it seems like that would be normal just from engaging the PTO in this type of system. Hard to tell from the pics but those original cam look to have an awful lot of flat surface on them.

Seems like on the new cams if the tiller is causing back and forth chatter the cam tooth will be banging the heck out of itself because the slot it fits into is so big. I don't know which is worse but it seems like there would be a lot more stress with the new design. A tighter fitting tooth would be ideal but it would probably make engaging the PTO a problem.

Is this cam design typical of this type of PTO? Seems like there ought to be a better way but I'm no engineer. I do see the advantages of an independent PTO now though.

 

[ccsial]

Is this cam design typical of this type of PTO? Seems like there ought to be a better way but I'm no engineer. I do see the advantages of an independent PTO now though.

I'm not a mechanical engineer either but I can envision a better system. It would cost more though.

My 1910 actually engages a gear when the PTO is on. I like that better.

 

[RayMunising]

One last observation. Most of you guys probably already know this and I'm not saying this has anything to do with Hammers problem but now that we all know what both the new and the old cams look like and if you think about how they operate there are two things you can do to really help the longevity of your PTO. 1) Idle your tractor WAY DOWN before engaging your PTO and 2) Don't engage the PTO with the implement under a load.

I know it probably tells you that in the manual and now that you've seen the cams you know why. Those cams need to FULLY mesh together in a fraction of a second. The faster one is spinning the harder that is to achieve. And when they do mesh together the spinning cam is going to hit that non spinning cam pretty hard. If the non-spinning cam can't freely get up to speed because the implement is locked up on something you're giving the system one heck of a jolt.

If you put two and two together, high PTO speed engaging with a non-freely moving PTO you have all the ingredients of a problem. The high speed may prevent full engagement of the cam teeth and if the implement is under load you've got a partially engaged cam tooth pushing against something that doesn't want to move.

Now add CCSIAL's thoughts on how a sloped cam with a chattering implement might act just like you're repeatedly engaging the PTO at full speed with an implement under load and you've got a design problem that the new cam does indeed correct.

Hmmm... what do you think guys? It sounds good on paper but the pictures of Hammers cams don't show a lot of damage.

 

[Goog]

I still have not heard from my dealer about the updated cam issue.

I showed my boss at work who is an old time farmer and he thought the cams with the ramps seemed like a good one way system. Something has to give when it is overdriven. He showed me some aftermaket one way pto drives that attach to your pto output.

I have looked several times at the pictures of the new part versus the old part. I still like the idea of the solid cam but it seems to me like it would be much stronger if it had four drive lugs instead if just two. It would also still engage easily with four as there seems to be plenty of surface area on the cams. I am not an engineer either but neither one looks really stout.

Does anyone know if the "kit" is just the two cams or does it have a different spring? Also are the current tractors pto only different by the use of these cams?

Last, it just happens that in yesterday's mail a two year survey came for me to rate my tractor and dealer. I think I will hold off on filling it out for a bit. Brian

 

[RayMunising]

I just reread page one of this thread (again) and Hammer says he idles down before engaging the PTO and the implement is not under a load so everybody probably already knows how important it is. On the reread though I did notice something that I either missed or just forgot (the mind is the first thing that goes) ... These cams are the diameter of a coke can. From those nice closeup pictures Hammer took of his cams I had in my head they were like 6 inches in diameter or something! If they are the size of a coke can those lugs are probably less than 1/2 inch tall! Kubota certainly didn't overbuild these cams. If I were in your shoes Hammer I'd stop trying to get the new cams installed. I'd just trade the tractor in! The B2910 served you well. I'm sure a B3030 would too. Life is too short. Your L2800 has very few hours and the PTO is in working condition. The longer you wait to trade it in the more it's going to cost you.

 

[JC-jetro]

I'm no expert and I don't even play one on TV but don't you think the problem lies in the spring (or whatever it is) that forces the 2 cams together when the PTO is engaged? I don't see how the chatter noise from the original cam design can cause any harm to the cams at all. Noisy - yes! Harmful - I don't see it. Actually the new locking cam is going to bang the backside of the cam tooth instead of sliding up the slope that the old cam had. The old cam would make the spring that forces the cams together really work as the overrunning action was spinning. That wouldn't be the case in the new style.

Looking back at the picture of the damaged cams Hammer posted way back when it sure looks to me like those cams would engage with each other without any problem if they were held together. How could they slip? The only way I can think of is the force that holds the cams together was not sufficient. A weak spring? Does that make sense to anyone else?

One thing that's for sure with either the new or old style cams there certainly is no feathering in engaging the PTO. It's going to engage with a heck of a force!

You are correct that the spring or lack of adequate stiffness can push the mating pieces away from one another. The PTO lever has to have some detent position with a ball or spring or Some sort of catch to maintaine the locked in position. If I understand on L2800 the PTO lever uses cable (same as motorcycle brakes... this is not good as you can maintain tension but no compression.... most tractor the lever is actually solid metal/rod with some pivot point to pull,push and change rotation.) Aside from that the cam design is still not good because of tremendous torque carried two two knife edges. A much better and proven coupling design is a sliding gear that mates two splined shaft (same as synchronizer gear in a transmission that transfer the torque from the main shaft to the lay shaft). this design with or without synchronizer is great as the torque is equally distributed to many hardened gear teeth. They already have that design in the transmission and why not spend a few $$$ and use it in lieu of cheesy cam design.

JC

 

[RayMunising]

I think I have an understanding of how the PTO works in the L2800/L3400. Can anybody explain to me in nice easy to understand terms how both the rear and mid PTO works in the GL3130/GL3240 HST?