Kubota GR2100 PTO Speed?

[Venturabass]

Hi, I've tried doing several searches across the internet as well as referring to my service manual. I'm trying to determine the rated speed of the PTO output shaft on the transmission for the GR2100.

This model is shaft drive. I see there is a driveshaft from the engine back to the transmission, and then a stub shaft coming off the transmission where you would link up a PTO shaft to drive a mower or blower.

Does anyone know what this speed is supposed to be?

 

[locknut]

Hi, I've tried doing several searches across the internet as well as referring to my service manual. I'm trying to determine the rated speed of the PTO output shaft on the transmission for the GR2100.

This model is shaft drive. I see there is a driveshaft from the engine back to the transmission, and then a stub shaft coming off the transmission where you would link up a PTO shaft to drive a mower or blower.

Does anyone know what this speed is supposed to be?

Yer lucky day,scroll down this page

http://www.mytractorforum.com/119-h...accessories/104059-kubota-gr-cab-build-6.html

 

[Venturabass]

Yer lucky day,scroll down this page

http://www.mytractorforum.com/119-h...accessories/104059-kubota-gr-cab-build-6.html

I browsed the post, looks like you measured 2,664 rpm at the PTO shaft? Assuming this was full throttle? This wasn't exactly what I was expecting. I guess I'd thought it'd be something more standard like 2,000 rpm. I understand it's all dependent on engine rpm. Do you know what spec is supposed to be, or do you only have this measurement?

Maybe spec is 2500 rpm based on your measurement?

 

[PHILIP8N]

Building a generator? Would love one off the front of my GR2120. Philip.

 

[Dave M7040]

Hi, I've tried doing several searches across the internet as well as referring to my service manual. I'm trying to determine the rated speed of the PTO output shaft on the transmission for the GR2100.

This model is shaft drive. I see there is a driveshaft from the engine back to the transmission, and then a stub shaft coming off the transmission where you would link up a PTO shaft to drive a mower or blower.

Does anyone know what this speed is supposed to be?

Mid pto speeds are a nominal 2,500 rpm. Why so high, because the lawn mower blades require a high blade tip speed to cut the blades of grass.
The higher rpm does not make any more power. The manufacturer may post a speed slightly higher or lower but it is not significant. They are trying to provide a speed which is the highest torque rpm for the engine.

When you mount a front snowblower and power it from the mid pto, the pto speed has to be slowed down at the blower to 540 rpm which is the speed most blowers are designed for as 540 is an industry wide standard. For snowblowers, there is a sprocket and chain assembly that the pto attaches to which lowers the speed of the blower fan to 540 rpm
This illustration for a kubota front mount blower is marked up to show you.

Many small front mounted snow blowers are made in Canada by RAD. They just paint them orange for Kubota, Green for John Deere, etc.
Their product design, as a proud Canadian I am ashamed to say, is very big problem.
Owners are going through shear bolts by the handful.
The shear bolts have one or two grooves cut in them to make them more likely to fail. When they break the three pieces fly out of are buried and an unsuspecting new owner finds the bolt head, goes to Home Depot and buys a bolt of the same grade, He does not know about the grooves and the next think he has an exploded gearbox costing $700+ for parts alone.

My friend had his dealer install a new front blower this winter. The dealer gave him some spare shear bolts. His blower has the newer design at the fan hub as the one with the black part, but the shear bolts are to be grade 2. The ones the dealer gave him, without a thought, are grade 5. This is another another disaster in the making.

This expensive failure happens.

Original design and shear bolt location

Expensive upgrade by the very best dealers replaces the fan and adds the black part to stop constant shear bolt failures.

My advice is to avoid buying a blower with the gearbox between the two halves of the auger. It is a glorified walk behind blower design.

Instead look for a blower made in Canada or the USA and using the same design for ssmall blowers as the ones for 300 hp tractors.
A gearbox behind the fan. An auger with a chain sprocket on one end which is driven from the gear box through a smaller sprocket and chain as this one by Smyth Welding.

Dave M7040

 

[Venturabass]

Hi Dave M7040. Snowblowers is exactly where I was going with this. The GR2100 is actually my Dad's. And YES he goes through fan shear bolts like crazy. I had posted on the other recent thread on this site that specifically describes the difference in shear bolt design. His is the older design that is missing the hub. I actually reached out myself to RAD about 2 weeks ago via email on the topic and specifically requested details on how I could get the improved design. Of course I heard nothing. My next step will be to call them.

You may feel disappointed about the shear bolt design fail, but I'll tell you that RAD is otherwise an AWESOME AWESOME machine. And quite frankly if we can get my Dad's fixed up so he's not eating pins every time, he will feel the same. I've never seen a blower through so far, at least not in this class range of tractors. I myself own a belt driven JD X540, and have the front mount Bercomac snowblower. As I mentioned in the other thread I've spoken to Berco several times, RAD was originated by Berco. The unit on my Dad's Kubota is almost identical to the Berco, other than the drive mechanism of course. But the chasis, chute, etc. The Berco has the four bladed fan however, and the updated shear bolt design as mine is only 2 years old.

Anyway back onto the speed thing. The reason I was questioning the speed thing is I was trying to compare the blower running speed for my Berco vs. Dad's RAD. The Berco's are known for throwing very far, even the belt drive models. My was lightly used 2nd hand, but I wasn't very impressed with it. That's until I put a tach on the Kawasaki V-twin and determined "full throttle" was only 3100 rpm. I adjusted the high idle on the carb to 3600 rpm and it throws much better at 50'. But my dad's still seems to throw a little further. I'm familiar with the sprocket chain reduction on the RAD. However, I don't agree with the 540rpm running speed. I know that is standard on rear PTOs as I'm sure you are. In my time on the phone picking the brains from Berco, they've told me the sweet spot speed for at the impeller on their front mounts was 1000-1200 rpm. There's a reason they sized the impeller diameter as such and that speed. The Berco guy was just a tech. A very knowledgable, but wasn't speaking engineering talk. I believe what he was trying to tell me is if you speed up the impeller too much you reduce throughput while gaining throwing distance. And as you decrease speed you reduce throwing distance, and at some point I'm sure you reducing throughput too. Maybe it has something to do with where the blower chokes out? Anyway I have a video of both our blowers at full speed and can tell you they're both running almost the same impeller speed. In that ~1000 rpm range. Any idea what those sprocket sizes are? I've never seen them other then in the parts diagram or through the oil hole in the steel shield. I'm assuming the small sprocket is at least 1.5" to 2" in diameter.

Other reason I was curious with a 2500 rpm speed on the GR2100 is most larger equipment with mid PTO uses the standard 2000 rpm, but it's also based on a #X spline shaft. I forget the number of splines, but this wasn't equivalent to what is on the GR2100.

With 540 rpm rear PTO speed, does a typical 3 ph snowblower have a reduction gearbox to speed up the blower speed? Or is it always 1:1? My assumption without ever seeing on is the way they get around the low PTO speed with a 1:1 drive is by making the impeller diameters much bigger than on a small front mount. With a 4' or 5' rear mount I've seen specs for 20" diameter impellers where a similar front mount is in the 14-15" range. Assuming they're using the faster tip speed on the rear mounts to propel the snow since rpm is so low. However, never actually owned one or looked up close to verify.

By the way with the newer shear pin design on my Berco, I've tried pushing it and it has yet to break an impeller shear pin. We just had a couple inches over night here and my Dad was telling me he broke 4 impeller shear pins on the RAD! UGH, frustrating.

 

[Dave M7040]

The blower in my earlier post with the chain reduction assembly is the same blower for 3 pt hitch use. Same fan, same auger same housing. Kubota wants the fan turning at approx the same speed on the front or the rear.

Consider buying a non contact hand held tachometer for approx $20 on Amazon. You put a small piece of reflective tape on what you want to measure and point the laser at it. Immediately the rpm no guessing.
Amazon.com: AGPtek(R) Professional Digital Laser Photo Tachometer Non Contact RPM Tach: Automotive

Once you have this tool I wont be trying to convince you of anything you can measure it and perhaps change my mind.

The fan diameter is in part based upon the life of the pto shaft based upon pto shaft joint angles. If you look at this chart showing pto shaft life vs joint angle you will realize the blower manufacturers want to have the fan shaft at the same height as the typical tractor's pto height to prevent short service life.

Very large tractors, 200-300 HP have two speed pto's 540 and 1,000 rpm. The manufacturer provides the 1,000 rpm pto because it can transmit say 300 HP with a smaller lighter pto shaft than transmitting the same 300 HP at 540 rpm.

Once you get to the blower there is a reduction gearbox to lower the 1,000 rpm to 540. Most of the gearboxes in this photo are to reduce the 1,000 to 540 rpm

If you can get RAD to talk to you you are doing far better than anyone else on the two forums. Lots of frustrated owners of their products but they leave it to Kubota, John Deere or which ever color product they painted the blower. I look forward to seeing anything you can get from them. On their web site you can go no where without special user and password.

Can you tell me where you can buy the wormgear gearbox on the RAD products other than through a dealer? I cannot find them. The dealer wants $700. My neighbour gave his dealer $1,500 to upgrade his RAD blower because he needed it to work now and did not have the time to chase people or parts.

Looking forward to your reply and of course whatever you get from RAD. Good luck.

Dave M7040

 

[Venturabass]

Your front mount on your Kubota is the same design as Kubota uses on the rear mount? The RAD front mount on my Dad's Kubota is as you describe: the sprocket reduction to a 15" impeller to the front gear case driving the auger. The RAD branded "Blizzard" 54" that they sell under their own name is a very different design. PTO shaft looks like it goes into a 2 way output gear box. One end drives a sprocket which drives the auger. No front gear box! The other end appears to be a 1:1 directly to the impeller. But take the 54" wide model. Intake height is much taller at 26", and impeller is huge at 24". Even the 48" rear model uses a 20" impeller. Wish I could post attachments here. I have the brochure for the Blizzard 3ph snowblowers.

I agree, you can't beat the sprocket/chain driven auger. What a simplistic system. And if anything goes wrong I think it's all standard size roller chains!

I definitely see your point in the diameter of the impeller for the 3ph models, with respect to PTO angles. I suppose they could also accomplish that with a chain drive like on the front mount, to transfer the power to a lower point where the smaller impeller shaft is located. More parts however. If the large impeller on the 3ph models was a conscious design effort to minimize the PTO angle, I'm willing to bet it is a dual purpose design meant to also increase that tip speed of the snow leaving the blower. I still don't think 540 rpm on the front mount sounds right. With the size of the impeller, I don't think it's possible to throw as far as these things do (50+'). With the Berco on my John Deere, I mentioned that Berco told me they design the impeller to spin between 1000-1200 rpm depending on your tractor model. Now I put a tach on the engine, and can verify it runs at 3600 rpm at full throttle. The Berco has 2 stages of speed reduction in the pulleys. I've run the ratios and I get about 1,060 rpm at the impeller.

That photo you posted of the broken front gear box, was that your friends blower who is facing the $700 in parts to rebuild?? $700 in parts? That is total insanity. Other than the case halves and the brass bevel gear, maybe a shim or seal, what else is there to replace right? Sounds like a hefty price on those couple of components. That's through Kubota or RAD? Have you tried using the Kubota part numbers and doing a global search on the internet? I'm assuming it's not through RAD, their website is useless.

This is probably a long shot, but I tend to naturally think of alternate solutions when something like this comes up. The photo below is from my Berco Northeast 48". Model is #700378-3.


You can download the manual on the Bercomac website which has the parts catalog. The full gearbox with impeller shaft (no auger shafts) is part # 104718. You can buy this on Salem Power Equipment, LLC for $328. I've bought a few things from them before and found them to be a good source of Berco parts on the shelf, which is almost non-existent elsewhere.

Here is a photo from Salem Power's website of what you get:

Is it possible this would work? Possibly. These seem to be essentially identical units, and RAD and Berco were founded from the same company. You might have to switch out the impeller shaft with worm gear from the Kubota as I'm sure the opposite end of that shaft is different on the Kubota. Berco may have some other Northeast model snowblowers that were shaft driven? If you go to the Salem Power website you can search for Berco parts and do a category search on gearboxes only to see what else is available from them. I wish I had a better answer but it sounds like RAD leaves you no option but to buy the very expensive Kubota labeled parts.

Actually on vacation for part of this week, enjoying the deep snows of New Hampshire! I do plan on calling RAD and seeing who I can speak to about the shear pin issues. I'll let you know where I get.

 

[Dave M7040]

Some homework for you since I visited the web sites you suggested.
Go to a Kubota or John Deere web site and find me a spec sheet for the front mount blowers they sell for their smaller tractors.
I have and cannot find any details. John Deere has a front mounted 76" one for a medium to large tractor with a loader that is hydraulically driven The hydraulic unit connects to the rear 3 pt and contains its own pump and reservoir. The front blower has a hydraulic motor. The fan speed is 540. The whole unit looks like a Normand unit painted green.

Rad has no details on their site. How is your French when you call them?

Normand is a huge snow blower company in the same area of Quebec. They will communicate with customers, however, my email was in english, their reply was in French.

I went to the Salem Power web site and this worm gear unit with shafts is a better match.

The worm gear upgrade kits are more interesting. What your dad needs perhaps. Certainly not cheap.

Now that I see the belt drive blowers are like ones for Cub Cadets, I don't have any experience with their speeds but still suggest you invest in a tach. Doing calculations on V belt reduction units is not as simple as counting chain sprocket teeth. You cannot just measure outside diameters.

On the Berco web site I cannot find any fan speeds for their products!

Dave M7040

 

[Venturabass]

As far as I know the Kubota and Massey front blowers are made by RAD but the John Deere units are not. The specs available on either the Kubota or Massey sites for these absolutely STINK, as you've also found. There is NO info on these! I'm familiar with the John Deere designs. When I bought my X540 it came with the 44" JD front snowblower. But I sold it 3rd party and bought the Berco 3rd party also. All the smaller garden tractors and sub compact JD's seem to be painted yellow, and they all have common design elements. If I had to guess, my guess would be that Deere makes them. When you get more into the compact class and above, the front blowers are painted green and marketed as "Frontier". Not sure if Frontier is a division of JD, or just a partnership, like what Massey is doing with Woods currently.

As I was saying about the garden tractor JD blowers, they have similar design elements. They use plastic fan wheels, with rather large clearances between the drum, they use plastic chutes on all but the shaft driven models, augers are non-serrated. My 44" JD blower also had a very very light auger gear. It looked like a slightly larger unit than what you'd find on an MTD walk behind snowblower, where there are 2 halves of a case form fitted around the gear, filled with grease, not an oil bath. In the later 44" SB years they came out with at least an oil bath gear case, which is what the 47" belt and 47"/56" shaft driven units always had. There were only a few models that have a steel impeller though. The JD worked decent enough, but my Berco definitely out-throws.

The one good thing about the Deere blowers is they actually have some specs available. Below are the specs for the 44" and 47" models that were available for my X540. These are right out of the online owners manuals for the models on the Deere website. Note the impeller speed which is consistent with what I calculated for my Berco.

John Deere
44" Snowblower (X500 Series)
Overall Length 77.5 cm (30 1/2 in.)
Clearing Width 1.1m (43 1/4 in.)
Scraper Blade Replaceable
Height to top of housing 46cm (18 in.)
Height to top of spout 100cm (40 in.)
Auger Speed 110 rpm
Auger Diameter 30.5 cm (12 in.)
Impeller Speed 1060 rpm
Impeller Diameter 35.5 cm (14 in.)
Lift Height (above ground level) 10cm (4 in.)
Lift Height (below ground level) 5 cm (2 in.)
Discharge Chute Rotation 200 Degrees
Net Weight 82 kg (180 lb)

John Deere
47" Snowblower (X500 Series)
Overall Length : 88.9 cm (35 in.)
Clearing Width 1.20m (47 in.)
Scraper Blade Replaceable and Reversible
Height (to top of housing) 49cm (19 1/4 in.)
Height (to top of spout) 1.08m (42 1/2 in.)
Auger Speed 200 rpm
Auger Diameter 40.6 cm (16 in.)
Impeller Speed 1060 rpm
Impeller Diameter 38.1 cm (15 in.)
Lift Height (above ground level) 10cm (4 in.)
Lift Height (below ground level) 5 cm (2 in.)
Discharge Chute Rotation 200 Degrees
Net Weight 95 kg (210 lb)

I may have missed some important details. So you have a Kubota M7040, is that what's equipped with the RAD snowblower? That's a pretty good size machine, how big is the width? At least 56"? More? Any idea the impeller diameter on that? Is this unit essentially identical more or less to the Kubota GR2728 or Massey 2360 that people have been complaining about regarding the shear bolt issues? If it's much bigger maybe that explains your 540 rpm impeller.

By the way, that's not necessarily an "easy" calculation as you mentioned to get the exact speed. I ran my numbers a few different ways assuming actual speed is based on pulley ratios measured at the midpoint of the belt, not just the pulley outer rim. Using this method provides an effective pulley diameter smaller than the overall pulley diameter. This reduction method does yield a slightly slower impeller speed, but I found it's still within the 1000 rpm order of magnitude. Once spring returns I'm going to try to get a measurement on the chain midpoint on my Dad's RAD to find out what that reduction is to the impeller. Looking at the parts diagram it's probably somewhere between a 2:1 or 3:1 reduction. If it really went from 2500 rpm to 540 rpm, that's a 4.6:1 reduction. It'd be a pretty big difference in sprocket sizes, something on the order of 1.5" and 7". They didn't look that drastic when I peered through the chain oil hole. I guess we'll find out come spring!

Also you're right, the Berco site doesn't give out speeds either. I only got the info I got by talking to their technician, it's always the same guy when I've had a technical question. He speaks both English and French, hopefully that's not my roadblock when I call RAD! Heck maybe I'll give Berco a call back too. I'm addicted to the throwing speed, but want more. I'd love to get 65-70'. I am an engineer by degree. I was looking back through my old dynamics books. I have some empirical data now from when I turned up the engine speed on the Deere to spec. So it threw about 38' at 3100 rpm and now about 50' at 3600 rpm. Turning up engine however is somewhat of a diminishing return because it's effect on impeller speed is diminished by the pulley reduction. However I'd love to play with some numbers and run the trajectory equation to see if I can get it to match my tested numbers, and predict what a change in pulley size could provide. The average linear impeller speed has a big impact on throwing distance, as the kinetic energy of the snow leaving the chute increases by the square of the increase of the velocity. A pulley size .5-1" less should be on the right order of magnitude. If I can find one from another Berco model that fits that'd be a good start. The proper size belt would be another question mark though I'd need to do some homework on. By the way how does your blower on the M7040 throw? That's quite a bigger machine than my Massey 1240 which is on older 28hp compact class. I bet your blower really flings the snow!

Those upgrade kits are interesting, I hadn't seen that on there nor do I know what it was??? I took a second look and also saw a couple of bevel gears too, but they were in the $200 range.